GST 123: Philosophy and Logic Module - Federal University Lafia PDF

FEDERAL UNIVERSITY LAFIA CENTRE FOR GENERAL STUDIES GST 123: PHILOSOPHY AND LOGIC MODULE NOVEMBER, 2018 1 Table of Contents FOREWORD............................................................................................................................. 5 FROM THE DIRECTOR.......................................................................................................... 6 CONTRIBUTORS..................................................................................................................... 7 GST 123-PHILOSOPHY AND LOGIC.................................................................................... 8 MODULE 1: INTRODUCTION TO PHILOSOPHY............................................................... 9 Introduction............................................................................................................................ 9 Objectives.............................................................................................................................. 9 WHAT IS PHILOSOPHY?................................................................................................... 9 Learning how to philosophize.............................................................................................. 10 Aims and Varieties of Philosophy....................................................................................... 11 A BRIEF SURVEY OF THE BRANCHES OF PHILOSOPHY........................................ 12 THE TRADITIONAL BRANCHES OF PHILOSOPHY............................................... 12 ETHICS............................................................................................................................ 12 EPISTEMOLOGY........................................................................................................... 13 LOGIC............................................................................................................................. 14 METAPHYSICS.............................................................................................................. 14 Study Questions................................................................................................................... 15 MODULE 2: PERIODIZATION OF WESTERN PHILOSOPHY I...................................... 16 Introduction.......................................................................................................................... 16 Objectives............................................................................................................................ 16 Background.......................................................................................................................... 16 ANCIENT PHILOSOPHY (6th Century B. C. – 4th Century A. D.)................................... 16 Study Questions................................................................................................................... 23 MODULE 3: PERIODIZATION OF WESTERN PHILOSOPHY II..................................... 24 Introduction:......................................................................................................................... 24 Objectives:........................................................................................................................... 24 2 MEDIEVAL PHILOSOPHY (5th - 13th Century).............................................................. 24 MODERN PHILOSOPHY (14th – 18th Century).............................................................. 25 CONTEMPORARY PHILOSOPHY (19th – 20th Century)............................................... 30 Study Questions................................................................................................................... 33 MODULE 4: INTRODUCTION TO LOGIC.......................................................................... 34 Introduction.......................................................................................................................... 34 Objectives:........................................................................................................................... 34 What is Logic?..................................................................................................................... 34 Principles and Nature of Logic............................................................................................ 35 Purpose of Logic.................................................................................................................. 36 The link between Logic and Language................................................................................ 36 Functions of language...................................................................................................... 37 LAWS OF THOUGHT.................................................................................................... 37 Study Questions................................................................................................................... 38 MODULE 5: ARGUMENTS AND FALLACIES.................................................................. 39 Introduction.......................................................................................................................... 39 Objectives:........................................................................................................................... 39 NATURE OF ARGUMENT................................................................................................ 39 Validity and Soundness of an argument.......................................................................... 40 FALLACIES.................................................................................................................... 41 Study Questions................................................................................................................... 44 MODULE 6: SYMBOLIC LOGIC........................................................................................ 45 Introduction:......................................................................................................................... 45 Objectives:........................................................................................................................... 45 Logical constants and sentential connectives...................................................................... 47 FIVE MAJOR LOGICAL CONNECTIVES....................................................................... 47 Study Questions................................................................................................................... 48 3 MODULE 7: TECHNIQUES FOR EVALUATING ARGUMENT....................................... 49 Introduction.......................................................................................................................... 49 Objectives............................................................................................................................ 49 ELEMENTARY VALID ARGUMENTS/RULES OF INFERENCES.............................. 49 TIPS ON APPLICATION OF THE NINE RULES............................................................ 53 Study Questions................................................................................................................... 54 SELECTED BIBLIOGRAPHY........................................................................................... 56 SOME PAST QUESTIONS AND ANSWERS................................................................... 57 4 FOREWORD As a citadel of learning, Federal University Lafia train students from every part of the country and beyond. In an effort to deliver quality education, the University has encouraged every Academic Department to produce resource materials for learning, to assist our students. The Centre for General Studies has taken the lead in answering this clarion call by the publication of this Lecture Module to serve as a reference material for both students and teachers in the University and other tertiary institutions. Considering the quality of the Lecture Module, it is hereby recommended as a reading material for those seeking comprehensive knowledge in GST courses. Importantly, and in accordance with the laudable core values of this Institution, I commend this innovative initiative of the Centre for producing this reference Academic material for our esteem students covering all the GST courses. With this, our students stand the chance of attaining high academic excellence especially going by the pedigree of the contributors of this work, who have painstakingly and succinctly produced this Lecture Module. Professor Muhammad Sanusi Liman Vice-Chancellor 5 FROM THE DIRECTOR The Centre for General Studies was established in 2012. The mandate of the Centre is to teach undergraduate students of the University those courses that are geared towards ensuring that every graduate has the basic knowledge in other disciplines in the University. Consequently, I humbly on behalf of the Centre for General Studies extend my warm welcome to all new and returning students taking the GST courses. I urge you to take advantage of this unique Module and other existing facilities at the University to make your stay a valuable one in order to achieve your desired future ambition. The Module is one tool that will assist and enhance your academic pursuit while in the University especially the GST courses. I therefore implore you to read, understand and make the very best use of the material and be assured that the Centre and its entire staff are always available for any clarification. Once again welcome to the Centre for General Studies and Federal University Lafia. Enjoy your stay while you attain excellence. Thank you. Nasirudeen Mohammed Baba, PhD, FICCON Ag. Director 6 CONTRIBUTORS 1. Oluwaseun Babatuyi - Coordinator Department of Philosophy, Federal University Lafia 2. Professor Kyrian Ojong Department of Philosophy, Federal University Lafia 3. Dr. Isaiah A. Negedu Department of Philosophy, Federal University Lafia 4. Aduragbemi I. Adegoke Centre for General Studies, Federal University Lafia 7 GST 123-PHILOSOPHY AND LOGIC This is a concise preparatory module to the study of philosophy and logic. As a general study course, some salient topics have been selected in accordance with the NUC required syllabus. The topics are thus divided into seven modules. The first three modules shall launch students into the basic introductory aspect of philosophy and historical survey of western philosophers as well as schools of thought whilst the last four modules shall examine basic preliminary topics in logic. Each topic is well introduced and presented in a simple style with copious illustrations and examples for better comprehension. At the end of each module, there are study questions for students to assess their grasp of the topic treated. The general topics captured in the module include the following: General introduction to philosophy and a brief survey of the branches of philosophy; History and periodization of western philosophy; Laws of Thought; Nature of Argument; Validity and Soundness of Argument; Techniques for evaluating arguments; Distinction between Inductive and Deductive Inferences with illustrations taken from familiar text including literature materials, novels, laws and paper publications; Fallacies; Symbolic Logic; Special symbols in symbolic logic; Methods of deduction using rules of inference and bi-conditionals. ‘Seun Babatuyi Co-ordinator, GST 123. 8 MODULE 1: INTRODUCTION TO PHILOSOPHY Introduction This first module familiarises students with the general idea of philosophy. It removes perceived misconceptions about philosophy and provides basic steps to learning how to philosophise. A lucid definition of philosophy is given as well as cursory consideration of branches of philosophy in order to ensure students’ understanding of the subject matter is realised. Objectives The objectives of this module include: - To make philosophy understandable to students - To clarify basic assumptions and misconceptions surrounding the course - To inculcate in every student the needed logical ability and philosophical attitude for everyday life. - To ensure students understand the branches of philosophy and its relevance to mankind WHAT IS PHILOSOPHY? Philosophy is a concept which has been used in many ways, some wider, some narrower. And this has resulted in diverse definitions of the concept depending on the perspective of the individual philosopher. - For instance, philosophy has been conceived by (Politzer) as a study or discipline that seeks to explain the universe and nature. Hence, it is the study of the most general problem of life and nature that are not given due attention by other disciplines. In this case philosophy is generally regarded as an abstract and abstruse discipline, far removed from the affairs of ordinary life. This of course is a disputable view. - Bertrand Russell, a very reputable Western philosopher believes that philosophy is something intermediate between theology and science. Like theology, it consists of speculations on matters as to which definite knowledge has, so far, been unascertainable. But like science, it appeals to human reason rather than to authority, whether that of tradition or that of revelation. - Following the above position, Russell contends that all definite knowledge belongs to science, while all dogma, pertaining that which surpasses definite knowledge belongs to theology. And that between theology and science, there is a “No Man’s Land”, exposed to attacks from both sides; this “No Man’s Land” is philosophy (Russell). 9 - Philosophy can as well be referred to as the basic beliefs or guiding principles of a person or group. In this perspective we do also talk of “philosophy” being the foundational principle of an enterprise, a discipline or a way of life. Hence, you hear people talking about their philosophy of life, i.e. the principles that inform their social actions or in-actions. And we do as well talk of the philosophies of particular disciplines such as Philosophy of Education, Philosophy of Law and a lot more. - In still another sense, we think of philosophy as an evaluation or interpretation of what is meaningful in life. On this account philosophy engages with what we call conceptual analysis or the clarification of concepts and their meanings just to enhance clear thinking in the derivation of human knowledge. If terms and concepts are not clearly defined in a conversation, we are likely to entangle our thoughts in errors and misapplication of ideas. Learning how to philosophize Step 1: Understand very well the etymological root meaning of the concept philosophy: taken from two Greek words namely: a. “Philo” which means LOVE; and b. “Sophia” which means WISDOM. c. Be a lover of wisdom Step 2: Know that wisdom means the practical and correct application of knowledge. Step 3: Develop a deep hunger for knowledge. Step 4: To achieve (3) above, develop an inquisitive mind by asking questions that will lead you to new knowledge. Here, Aristotle tells us that philosophy begins with “wonder”; that is, the art of wondering about the cosmos: e.g. what is this? What is that? Why is it so and not the other way? What is its origin? What if it is not the case? Etc. Step 5: Know that the process of being inquisitive and asking questions helps you to begin to think. Here, originality of thought is very important in the art of philosophizing. Step 6: Try to be logical in your thinking. E.g. “if a tree falls in the forest, will it make a sound if there was nobody there to hear it?” “If there were five birds on a tree and a hunter shoots one, how many will be left on the tree?” Step 7: Be dispassionately objective and let the facts speak for themselves. Step 8: Know that philosophy seeks only the truth and nothing but the truth. 10 Step 9: Avoid dogmatic ways of thinking, that is, be willing to consider the merits of counter views or opinions because you could be sincerely wrong in your own views/opinions. Always yield to superior reasons or arguments. Step 10: Develop a critical mind because knowledge grows by positive criticism. In this case also avoid the disposition of negative criticism especially when a particular point of view does not favour you. Aims and Varieties of Philosophy - It has been observed that the people who have engaged seriously in philosophizing have had varying aims. Some have been religious leaders, like Saint Augustine, that have tried to explain and justify certain points of view. Some have been scientists, like Rene Descartes, who have attempted to interpret the meaning and importance of various scientific discoveries and theories. - Other philosophers like John Locke and Karl Marx, have philosophized in order to effect certain changes in the political organization of society. And many other philosophers have been interested in justifying or propounding some set of ideas which they thought might aid human development in diverse spheres of life. But a lot more philosophers have no such purpose. Rather, they engage in critical and philosophical speculations merely to understand certain features of the world in which they live, and certain beliefs that people hold. - Now, let us conclude this section by outlining in form of a summary Harold Titus’ five possible understandings of what philosophy is: a) Philosophy is a personal attitude towards life, and the universe. He notes that, the mature philosophical attitude is the searching and critical attitude. It is the open-minded, tolerant attitude expressed in the willingness to look at all sides of an issue. b) Philosophy is a method of reflective thinking and reasoned inquiry. A philosopher thinks about certain matters in certain ways. He or she wants to find out what we base our knowledge on, what standards, should be employed in arriving at sound judgments. c) Philosophy is an attempt to gain a view of the whole. It seeks to combine the conclusions of the various sciences and human experiences into some kind of consistent world view. That is, it attempts to unify the various fragmentary views of life. 11 d) Philosophy is the logical analysis of language and the clarification of meanings of words and concepts. e) Philosophy is a group of problems as well as theories about the solution of such problems. A BRIEF SURVEY OF THE BRANCHES OF PHILOSOPHY We often divide philosophy into two broad divisions, namely: the traditional branches and the applied branches. The traditional branches of philosophy are basically four, viz: Epistemology, Metaphysics, Ethics, and Logic. The applied branches are as many as the diverse field of study in human endeavours, hence applied philosophy includes: philosophy of science, philosophy of language, social and political philosophy, philosophy of arts, philosophy of law, philosophy of mathematics, philosophy of education, philosophy of religion, and philosophy of social sciences among others. THE TRADITIONAL BRANCHES OF PHILOSOPHY On a general note, the traditional branches of philosophy are: (a) Ethics (b) Epistemology (c) Logic (d) Metaphysics ETHICS This is the branch of philosophy, which has the morality of human actions as the object of its study. Ethics has been classified into three main areas. These are (a) Normative ethics (b) Metaethics and (c) Descriptive ethics. a) Normative ethics: Is the most prominent division of ethics since the time of Socrates, Plato and Aristotle. This aspect of ethics attempts to discover some acceptable and rationally defensible views according to what kinds of things are good or desirable to aim at, in human actions, and what kinds of acts are right and why we admit that they are right. Thus, normative ethics is concerned with the norms and standards or principles of human behaviour. b) Meta-ethics: Inquiries into the meaning as well as inter-relation of the meaning of ethical terms. The fact here is that great controversies surround most of the moral words that are used in ethics. Such words as “good”, “bad”, “duty”, “obligation”, “right” and 12 “wrong” are often used in moral discussions, but their meanings depend on the context in which they are used. Thus, meta-ethics attempts to clarify the meaning as well as the implications of such ethical terms in order to enhance our understanding of the appropriate use of such terms in ethical propositions and judgments, in the determination of whether or not a particular human action is good or bad. c) Descriptive ethics: Examine moral views that are actually held by various people or societies. The aim of the study is to establish the fact as to whether such ethical views are universally held. The main object of descriptive ethics, therefore, is the discovery of the nature of morality. And by this task, descriptive ethics helps to reveal the different expressions of, and opinions about morality. EPISTEMOLOGY The term “epistemology” is derived from the Greek word “Episteme”, meaning knowledge. Thus epistemology is the branch of philosophy which deals with theories of knowledge. In the main, theories of knowledge are concerned with the nature and scope of human knowledge. To achieve this goal, epistemologists attempt to find answers to such questions as “what is knowledge”? “Can one know what he knows?” “What are the pre-conditions of knowledge?” These questions are all aimed at explicating the nature of knowledge and how to establish the claim that one actually knows what he claims to know. Contemporary interest in the nature of knowledge has in fact transcended epistemology as a branch of philosophy to such fields of study as information theory, artificial intelligence, and cognitive science”. The attempt to find cogent answers to the age-long skeptical challenge that knowledge is impossible, has also led to the development of such new trends and perspectives in epistemology as the quest for the foundation of knowledge, which now goes under the name “foundationalism” or “internalism”, the question of epistemic justification and the attempt to either naturalize or humanize epistemology, or to re-normalize epistemology by accepting the usual normative status of epistemology. The problems of knowledge that epistemology attempts to grapple with can be brought into focus by challenging the common sense attitude toward knowledge with the simple but loaded question “what can I know?” When we try to describe how we know something, we will discover that we do not really have a clear idea of what it means to know. This will, for example, lead us to the question of the sources of knowledge. In this connection, two schools of thought have emerged; Empiricism and Rationalism. While the latter maintains that knowledge is acquired through the process of reasoning, the former school of thought believes 13 that sense experience is the main source of knowledge. These are related problems of knowledge within the purview of epistemology. LOGIC Logic as a branch of philosophy is a science, which studies forms of thinking such as judgments, inferences, concepts and proofs in terms of their logical structure. The central aim of logic is valid reasoning. This is why logic is commonly referred to as the science of correct reasoning. There are two main branches of logic namely, formal logic and philosophical logic. The latter is also known as logical theory. The main task of formal logic is to formulate laws and principles whose observance is requisite for achieving valid knowledge. Philosophical logic, on the other hand, examines the concepts involved in formal logic. It also studies the nature of logical systems. Generally speaking, logic studies the laws of thought, types and nature of fallacies that bedevil thinking patterns, kinds of reasoning, namely, inductive and deductive reasoning. METAPHYSICS The term “metaphysics” simply means that which comes after physics. It is the title which an ancient editor by name Andronicus gave a collection of Aristotle’s essays. Now, because this book of essays which Aristotle has called first philosophy came after his other works covering the biological and physical sciences, the editor labelled it “meta-physics”. The prefix “Meta” is a Greek word meaning “after”. Thus, metaphysics simply means that which comes after physics. This conception of the root meaning of the concept metaphysics enables us to understand the nature of inquiry that this branch of philosophy undertakes. In this connection, we should note that the Greek word “meta” also means “beyond”. And so the term “metaphysics” refers to the subject matter or reality beyond physical nature or beyond the things we perceive. Thus, in metaphysics attempt is made to study the highest principles of all that exist. In other words, the problems of metaphysics have to do with “what is”. Hence, the traditional metaphysical problems dating back to the ancient Greeks have attempted to examine what is and to classify or categorize reality. For example, in metaphysics reality has been divided into temporal and non-temporal, material and non-material, mental and non-mental. The problem of change, appearance and reality, universals and particulars freewill and determinism, and permanence are some of the puzzles that metaphysical inquiry attempts to shed light on. In answering the questions about the nature of ultimate reality which metaphysics grapples with, two major schools of thought have emerged, namely: Idealism and Materialism. For Idealism, the ultimate reality is minds/spirits/ or ideas and that everything in existence is 14 ultimately reducible to ideas. Materialism on the other hand posits that matter is the ultimate reality and the only thing that exists, or that anything that exists depends on matter. It is a form of naturalism, a position that moves for the rejection of any supernatural entity or spiritual reality. Instead, it claims that the only thing that exists is that which in principle or practice can be scientifically investigated. Study Questions 1. “Wisdom” in philosophical search implies ----- 2. Discussion in ethics can fall into three categories. What are they? 3. Outline the Harold Titus’ five possible understandings of what philosophy is. 4. Briefly discuss the four traditional branches of philosophy 5. Identify and discuss the applied branches of philosophy 6. ____defined philosophy as something intermediate between theology and science 7. Who said that between theology and science, there is a “No Man’s Land” and why? 15 MODULE 2: PERIODIZATION OF WESTERN PHILOSOPHY I (ANCIENT PERIOD) Introduction The most popular historical account of philosophy available today is that of western philosophy, hence this module is a survey of major periods and key figures in western philosophical account. This historical survey shall be done taking into consideration, philosophers and their contributions from ancient times to the contemporary era. Objectives The objectives of this module include: - To ensure students are kept abreast of the origin and historical account in philosophy - To introduce students to philosophers along major philosophical epoch and their contributions - To establish the philosophical foundation of major theories and practices of the world. - To provide Greek philosophers as the founding fathers of western philosophy Background Philosophy is as old as the history of human race. But when we mention western philosophy, it is usually in reference to various discussions in philosophy that exclude the philosophy of certain continents, such as Eastern philosophy of China, Indian, Japan, Persia, or African philosophy. The origin of this western philosophy is traceable to Ancient Greece in about 6 th Century B.C. How it began and grew to what we now have in our contemporary era, as well as prominent scholars who have made notable contributions shall be highlighted and discussed in this section. ANCIENT PHILOSOPHY (6th Century B. C. – 4th Century A. D.) The seaport town of Miletus in Asia Minor was the birthplace of Western philosophy. The age of mythology preceded the age of actual philosophy. Below are some prominent figures and their contributions to philosophy of their period:  Thales: (a) He was the father of Western philosophy. (b) He predicted the eclipse of the sun which occurred on May 28, 585 B.C. 16 (c) He devised a way of measuring the Egyptian pyramids, using the simple procedure of measuring a pyramid’s shadow at that time of the day when a man’s shadow is equal to his height. (d) He philosophized that water was the first principle or primary stuff of all things. (e) He divided the month into 30 days and the year into 365 days. (f) Theorized that the shape of the earth is flat as a disc that floats in water.  Anaximander: - He propounded that the primary substance of the universe is the indeterminate boundless; the ‘Apeiron’. - Theorized that the earth is cylindrical in shape.  Anaximenes: a. The original stuff is air, for just as our soul, being air, holds us together, so do breathe and air encompass the whole world. b. Was the first to hit upon the highly respectable concepts of ‘rarefaction’ (expansion of air) and c. ‘Condensation’ (congealing of air) as the specific forms of motion for describable changes in air.  Pythagoras: a. All things consist of numbers, i.e., there is a numerical basis for all things which have size and shape. b. Believed that the study of science and mathematics was the solution to the mystical problems of purification and immortality.  Heraclitus: a. Change is the principle of things; all things are in perpetual flux, you cannot step into the same river twice, since fresh waters are ever flowing upon you. 17 b. The primary stuff is an ever-living fire. c. God, as Logos or Reason, is the universal law imminent in all things. d. All men share commonly in God’s universal Reason. This is the basis of the idea of cosmopolitanism or the brotherhood of mankind. e. The conflict of opposites is not a calamity but the permanent condition of all things.  Parmenides: a. Permanence is the condition of all things. Since reality is one, there can be no change or motion. b. Non-being and becoming are impossible. Being simply is.  Zeno of Elea: a. A disciple of Parmenides, proposed four ingenious arguments or paradoxes (The Race course, Achilles and Tortoise, the Arrow and the Relativity of Motion) to show that change or motion is impossibility  Empedocles: a. Speculated that the forces of love and hate, or harmony and discord are the positive principles in nature responsible for the intermingling of the four eternal elements (water, air, fire and earth) to form objects and later to separate to cause extinction. b. He was the first to pose the problem of natural selection as the basis of biological evolution.  Anaxagoras: a. His major contribution was the concept of mind (nous), which he distinguished from matter. b. Earth is the basic stuff of the universe. 18  Leucippus: Theorized that nature consists of two things only namely, space, which is a vacuum and atoms, which are the smallest indivisible particles of things. The stuff about which Thales, Anaximenes, Heraclitus and Empedocles spoke, namely, water, air, fire and earth respectively, are simply different clusters of changeless atoms. NOTE: Most of the pre-Socratic philosophers were concerned with cosmogonic speculations. Cosmogony is the study of the origin, creation and evolution of the cosmos (ordered universe). Thus, philosophy of this era is said to be cosmo-centric.  The Sophists: a. They were not concerned with speculations about the cosmos but with the problems of truth and goodness. b. They taught the youth and prospective politicians the art of rhetoric (persuasive speech). c. Prominent among the Sophists were Protagoras, Gorgias and Thrasymachus. d. Protagoras is best known for his statement that “man is the measure of all things, of the things that are, that they are, and of the things that are not, that they are not”. To say that man is the measure of all things is to_ say that our knowledge of all things is measured by what the individual perceives. e. Gorgias was the skeptic who propounded the extraordinary notion that nothing exists, that if any thing exists, it cannot be understood, and that even if it is understood, it can not be communicated (in words) to others. f. Thrasymachus defined justice as the interest of the stronger and held that might is right. He also said that laws are formulated by the rulers for their own selfish interest. 19  Socrates: a. He was the mouth-piece of Plato in many of Plato’s Dialogues. b. The interior man (the soul or psyche) is the seat of a unique activity, the activity of knowing which leads to the activity of doing. c. The surest way to attain certain or reliable Knowledge is through the practice of disciplined conversation, acting as an intellectual midwife, a method he called dialectic, and by which he hoped to help individuals deliver the knowledge innate in them but which they were ignorant of. d. There are two levels of knowledge namely, inspection of facts (particular things) and interpretation of facts (general or universal ideas or conceptions). e. His celebrated statement or dictum is “Man know thyself”. f. He equated virtue with knowledge, and vice with ignorance. g. Socrates was brought to trial by the Athenian authorities on the charge that he was introducing strange religious practices and corrupting the youths. He died of drinking Hemlock, a poisonous potion.  Plato: a. He theorized that there are four levels of knowledge, namely, imagining, belief, thinking and perfect intelligence. b. He bifurcated the world into the word of things (changing) and the world of forms (eternal or unchanging). c. The soul has three parts, namely reason, spirit and appetite. d. The state is man ‘writ large’. e. The three parts of man’s soul are related to the three strata or classes in the society: the individual appetites related to the class of workers who satisfy these appetites (the craftsmen or artisans) there is a connection between the spirited in 20 man and the large scale version of this force in the military (the guardians or solders), there is a deep connection between the rational element in men and the unique function of leadership in the ruler (the philosopher-King). f. The gradual transition from aristocracy through timocracy, plutocracy, democracy to despotism is a gradual decline in the quality of the state corresponding to a gradual decline in the moral character of the ruler and his subject. g. His most popular book is titled The Republic. His concern here is with the question-who should rule?  Aristotle: a. Inventor of syllogistic (deductive) logic. b. He distinguished between three types of reasoning, namely: dialectic (reasoning from facts that are generally accepted), eristic (contentious reasoning) and demonstrative (where the premises from which reasoning start are true and primary). c. He saw metaphysics as, the study of Being and its principles and causes. d. Substance is the essential nature of a thing. It is the composite of form and matter. e. His four causes are the “Formal cause”-that which determines what a thing is. “Material cause”-that out of which a thing is made’. The “Efficient cause”-the means by which a thing is made e.g the sculptor who makes the statue. “Final cause”-the end or purpose for which a thing is made. f. The highest good of man is happiness, and happiness is a working of the soul in accord with right reason. g. Man is by nature a social or political animal. h. Aristotle advocated aristocracy as the best form of government. 21 i. He is remembered for his statement that ‘equals should be treated equally, and unequals unequally’.  Epicurus: a. He said that the chief aim of human life is pleasure. He was therefore a hedonist. b. The ultimate pleasure human nature seeks is repose, i.e., the absence of pain and the gentle relaxation of the mind. c. Everything that exists in made up of small, indestructible bits of hard matter called atoms.  The Stoics: a. Prominent among the stoics were Zeno (the founder of stoicism), Cleanthes, Aristo, Cicero, Seneca and Emperor Marcus Aurelius. b. Matter is the basis of all reality. c. All events in the universe are under the control or influence of fate and providence. d. The cultivation of indifference or apathy leads to the achievement of happiness and serenity which are the marks of a wise man. e. Universal brotherhood and the doctrine of a universal natural law are among the most important contributions made by Stoics to the Western mind.  The Skeptics: a. The most outstanding skeptics were: Pyrrho (the founder of the school of skepticism), Arcesilaus, Carneades and Sextus Empiricus. b. They all believed that the senses are deceptive, that moral rules raise doubts, and that morality is possible without intellectual certainty.  Plotinus: a. He was a Neo-Platonist who believed that the One or God is Absolute Unity. 22 b. In his metaphor of emanation, God is at the apex, followed by the World Soul, then the Human soul and then the World of Matter, in a descending order. c. Evil is the discrepancy between the soul’s right intention and its actual behavior. d. Salvation is achieved through right conduct, correct thinking and the proper dispositions of the affections. Study Questions 1. Who are the Ionians philosophers? 2. What was the primary quest of the pre-Socratic philosophers? 3. Name and briefly discuss any three sophists you know 4. Discuss the major contribution of Plato and Aristotle to philosophy 5. Juxtapose the views of the Epicureans with the Stoics 23 MODULE 3: PERIODIZATION OF WESTERN PHILOSOPHY II (MEDIEVAL-CONTEMPORARY) Introduction: The reflective activities which philosophy is known for has been done along sequential order such that there is a link between the ancient period and the contemporary era. This module is set to establish the connection between the past and the present in western philosophy. It reveals various paradigm shifts which have occurred in western thought overtime. The medieval, modern and contemporary era have had several philosophers whose significant contributions to general worldviews cannot be overemphasised. Their views and contributions shall be considered in this module. Objectives: - To introduce students to prominent philosophers and their postulations along historical epoch - To acquaint students with major paradigm shifts which have occurred from the medieval period until now. - To point out the relationship of philosophy with institutions such as religion, politics, governance and education among others. - To bring to students’ knowledge major schools of thought and philosophical problems from medieval to contemporary period of philosophy. MEDIEVAL PHILOSOPHY (5th - 13th Century)  The period marked the confluence of philosophy (reason) and theology (faith)  The guiding principle of this period was that all knowledge upon all subjects must take cognizance of the revealed truth of scripture along with the insight of philosophical dictum of this period.  “Faith precedes reason” was the philosophical dictum of this period.  The medieval philosophers were church ‘Fathers’ who were mainly preoccupied with proving the existence of God and explaining the phenomenon of evil. 24  Prominent among these church “Fathers” were: St Augustine, St. Anselm and St. Thomas Aquinas.  All held that creation is ex nihilo, i.e., out of nothing.  Both Augustine and Anselm propounded the ontological proof of God’s existence, while St. Thomas Aquinas formulated five proofs ways of demonstrating the existence of God. They are: Proof from Necessary versus possible Being, Proof form the degree of perfection, and proof from the Order of the Universe.  In The Two Cities, St. Augustine distinguished between the ‘city of God’ (those who love God) and ‘city of the world’ (those who love self and the world).  Aquinas distinguished four kinds of laws, namely eternal law (based on Divine Reason), Natural Law (broad general principles reflecting God’s intentions for man in creation), Human Law (specific statues of governments), and Divine Law (base on Scripture).  William of Ockham a. He warned that we should not multiply entities beyond necessity. This has come to be known as ‘Ocham’s razor’. b. Universals are only words. This view became known as terminism nominalism MODERN PHILOSOPHY (14th – 18th Century)  This was a period marked by interplay between philosophy and the emerging world of Science. It was a period of enlightenment, emancipation and discovery.  The renaissance interlude featured such names as Erasmus (the literary critic)/ Luther (a passionate reformer). Machiavelli (the man who equated the right with the expedient, and argued that morality must give way to sheer power if the ruler must succeed) and Montaigne (the man who tried to revive ancient skepticism).  Observation and mathematical calculation became the hallmarks of knowledge. 25  Francis Bacon and Thomas Hobbes advocated the inductive and deductive methods of science respectively.  Bacon named the three distempers (diseases) of learning as fantastical learning, contentious learning and delicate learning.  Bacon believed that the human mind is corrupted by four idols which he metaphorically called the idols of Tribes, the Cave, the Market Place, and the Theatre.  As a political philosopher, Hobbes is frequently, though not accurately, called the father of totalitarianism.  Hobbes’ most popular book is titled Leviathan  Hobbes described what he called ‘the state of nature’, i.e. the condition of men before the emergence of civil society. In his words, the state of nature was short, and brutish.  Hobbes said that men enter into a civil society through an agreement between them i.e. through a social contract.  Law, for Hobbes, is a command of sovereign.  Rationalism, the view that reason is the principal source of knowledge, was founded by Rene Descartes.  Descartes and other rationalists (Spinoza and Leibniz) sought to formulate clear rational principles that could be organized into a system of truths from which accurate information about the world could be deduced.  For Descartes, the human mind possesses two powers, namely intuition and deduction.  Descartes used method of systematic doubts to find a absolutely starting point to build up our knowledge.  He used Cogito ergo sum (I think therefore, I am) to affirm his own existence. He then employed this basic truth to reverse his doubt about the self, things true ideas and God. 26  On the mind-body problem, he held a dualist/interactionist position and even tried to locate the point of interactions between mind and body at the pineal gland, located at back of the brain.  Spinoza was a pantheist who held that the realms of thought and extension (spirit and matter) are two modes or attributes of the same substance-God.  For Spinoza, there are three levels of knowledge, namely, imagination, reason and intuition.  Leibniz held that true substances are immaterial, windowless monads or souls whose isolation from one another and separate purpose form a large harmony.  Empiricism, the view that sense-experience is the chief source of human knowledge, was held by Locke, Berkeley and Hume.  Arguing that the mind is like a tabula rasa from birth, Locke dismissed the existence of innate ideas.  According to Locke, all men’s ideas can be traced either to sensation or reflection and these ideas are either simple or complex.  To answer the question of how ideas are related to one another, Locke distinguished between primary and secondary qualities, the former being the qualities inherent in the objects while the latter do not belong to the objects but are powers to incite or produce certain sensations or ideas in us.  Substance is the ‘thing’ in which all the qualities subsist. This ‘thing’ is something we know not what.  Locke was a strong advocate of private property.  Berkeley’s celebrated formula is esse est percipi- to be is to be perceived. For this reason, he has been dubbed a subjective idealist. 27  While rejecting metaphysics, David Hume gave empiricism its clearest and most rigorous formulation.  For Hume, impressions and ideas make up total content of the mind.  While rejecting the idea of causality, Hume argued that the idea of causality arises in the mind because of certain relations which we sometimes experience as existing between object. They are Contiguity, Priority in time and Constant Conjunction. A fourth one is the idea of necessary connection. Hume rejected all these, arguing that causality is not a quality in the objects we observed but is rather a habit of association in the mind produced by the repetition of instances of A and B.  Kant is sometimes described as the critical mediator between Dogmatism and Skepticism.  After making a distinction between a priori (analytic) and a posteriori knowledge (synthetic), Kant argued that synthetic a priori knowledge is possible.  Kant’s Copernican revolution consisted in the idea that the mind is structured in such a way that it imposes its way of knowing upon the objects.  Kant distinguished between phenomenal reality (the world as we experience it) and nominal reality (a priori categories of thought).  For Kant, Our attempts to achieve a science of metaphysics are doomed to failure. Whenever we try to discuss the self. the cosmos or God as though they were objects of experience, the inability of the mind to do so successfully is indicated by what Kant calls antinomies. The term ‘antinomy’ conveys the idea that when we discuss the nature of the world beyond experience, we can argue with equal force on opposite sides of various propositions.  Kant defined good terms of goodwill saying that nothing can possible be conceived in even out of it. Which can be called good, without qualification, except a good will. 28  Kant formulated his famous maxims which he called categorical imperatives. He argued that the truly moral imperative is categorical, meaning that it applies to all men and commands an action as necessary of itself without reference to another end. Categorical imperative commands a law that forms the bases of particular actions.  For Kant, our experience of the moral law suggest some further insights into the moral postulates of freedom, immortality and God.  Hegel set forth the general proposition that what is rational is real and what is real is rational and from this concluded that everything that is, is knowable.  Hegel’s dialectical process exhibit a triadic movement from thesis to another and finally to synthesis.  Hegel believed that the history of philosophy is the development of the Absolute’s self consciousness in the mind of man. History is moving toward a purposive end, namely, freedom. The highest freedom occurs when the individual acts according to the universal, rational will of the society.  Auguste comte is called the founder of positive philosophy. (Positivism). Comte said that the history of ideas indicates that there has been clear movement of thought through three stages, namely, theological, metaphysical and positivistic. Each stage represents a different way of discovering truth. For Comte, to deal effectively with questions of political order required a carefully worked out science of society which he did not find already available and which he, therefore, set out to create, calling it sociology-the sciences, the summit of knowledge.  Jeremy Bentham and John Start Mill propounded the philosophy of Utilitarianism, according to which, an action is good or bad according to the tendency it appears to have to augment or diminish happiness for the greatest number of people affected by the action. 29 CONTEMPORARY PHILOSOPHY (19th – 20th Century)  There were the philosophers of evolution such as Herbert Spencer (1820-1903), Henri Bergson (1859-1941) and Teilhard de Chardin. All of them saw cosmic development as the evolution on life.  Edmund Husserl (1959-1938) propounded phenomenology as a method of philosophy. Phenomenology is concerned with the essence of things and not with their concrete existence as individual things.  Pragmatism, an American movement founded by C. S. Pierce and developed by William James and John Dewey, is a philosophical theory of meaning and truth or meaning of an idea depends on its ‘cash value’ i.e on its function and practical effects if it accepted and acted upon.  Karl Marx (1818-1883) propounded the philosophy of Dialectical Materialism which later became the official philosophical doctrine of former Soviet Union. a. Marx’s dialectical materialism is a full-scale programme embarking Hegel’s dialectics and Feuerbach’s materialism. b. Marx called the material order or base of the society substructure and the order of thought superstructure. c. For Marx, the history of man is the history of class struggle. d. For Marx, the existence of surplus – value constituted the contradiction in the capitalist system. e. For Marx, the final and highest stage of society is communism (classless social order).  Existentialism (The Philosophy of human existence) is about the most influential movement in the 20th century. 30 - The major existentialist thinkers of the 20th century are Karl Jaspers (1883-1969), Martin Heidegger (1889-1979), Gabriel Marcel (1889-1980), Maurice Merleau Ponty (1908-1961), and Albert Camus (1913-1960). - All existentialists agreed that ‘existence precedes essence’. - Some of the main themes of existentialism are: irrationalism, ‘man as a being-with- others’, freedom, anguish, commitment, the facticity of human existence and death.  Analytic philosophy is the dominant movement in philosophical activity in the contemporary English-speaking world. - The movement aimed at ridding philosophy of all metaphysics and hence makes it something more like science. The method that will enhance the unity of all sciences is another aim of the movement. - What unites all analysis philosophers is agreement that the central tasks of philosophy is to clarify the meaning of language.  G. E. Moore (1873-1958) attacked idealism and proposed a commonsense view of the world.  Bertrand Russell and A. N. Whitehead propounded logical atomism, according to which, the words of a proposition correspond one by one with the components of the corresponding facts.  Ludwig J. J. Wittgenstein, in his picture theory of meaning as expounded in his book Tractatus Logico-philosopicus (1919), said that ‘whatever can be said at all can be said clearly’, and whereof one cannot speak, therefore one must be silent’.  Members of the group called Logical positivism who styled themselves the ‘Vienna Circle’, called for a rejection of metaphysics, and the grounds for this rejection were to be found in their famous verification principle, according to which, the meaning of a statement is the method of its verification. 31  W. V. O. Quine attacked what he called the “Two Dogmas of empiricism”. The first dogma is the distinction between analytic and synthetic statements and the second is the principle of reductionism which holds that every meaningful statement is reducible to a statement about immediate experience.  The emergence of the “New Wittgenstein” marked a turning point in analytic philosophy. In his new book Philosophical Investigation (1953), Wittgenstein deviated from the earlier view that language had the singular function of picturing facts. He now held that language does not contain one single pattern alone, that it is as variable as life itself. He therefore argued that analysis should no longer consist in the definition of language or its meanings but rather in a careful description of its uses.  There were philosophers who were concerned with the analysis of moral language. Here we can mention such names as Sir David Williams Rose, Charles L. Stevenson and R. M. Hare. These philosophers represent respectively the best exponents of three theories in contemporary British moral philosophy, namely, Intuitionism, Emotivism and Prescriptivism.  Karl R. Popper boldly attempted to solve the age-long problem of induction. He proposed his falsificationist methodology (trial and error method) of science.  Imre Lakatos proposed Scientific research Programme as the unit of appraisal in science.  Thomas Kuhn advanced his “Historical and Revolutionary science’ whose main feature is the notion of a ‘paradigm’.  Paul Feyerabend proposed an anarchistic approach to science. He dismissed all science as inadequate, arguing that the best ‘method’ of science is ‘anything goes’. Science, for him, is a fairy-tale, an ideology 32 Study Questions 1. Mention major figures and problems addressed in the medieval era 2. Is philosophy the same theology? 3. Who is Francis Bacon and what are his major contributions? 4. What is the difference between rationalism and empiricism? 5. Who is Karl Marx? 6. What do you know about logical positivism? 7. What is analytic philosophy? 8. What is phenomena and noumena, and who made the distinction between them? 9. What is Existentialism and in which period of philosophy did it become prominent? 10. Happiness for the greater number of people is the basis of ___ 33 MODULE 4: INTRODUCTION TO LOGIC Introduction This section is concerned with the art of reasoning and the method of doing this in a correct way whether with the use of established rules or in our day to day activities. To set the record straight, all reasoning is thinking but not all thinking is reasoning. Logicians are not concerned with the ways the mind arrives at its conclusions in the process of reasoning, but the correctness of the completed process. It finds out whether the premises of a statement adequately support its conclusion. Objectives: - To make students understand the meaning, nature and purpose of logic - For students to be able to demonstrate capacity for logical thinking in academic assignment and daily activities - To enable students not only to differentiate between good and bad arguments but to stick to the former whilst avoiding the latter What is Logic? Logic can be defined as the art and science of reasoning. It is the method and principles used to distinguish correct from incorrect reasoning. It is the systematic process of valid reasoning through inference — deriving conclusions from information that is known to be true. It is the area of philosophy that is concerned with the laws of valid reasoning. It is the aspect of philosophy that centres on and grapples with the issue of correct and effective reasoning. It also looks into the basic processes involved in arriving at valid reasoning as well as the principles that guide the making of correct inference. This is not a univocal definition because there are as many definitions of logic as there are definers. To start with, Copi I. M (1982) defines it as the study of methods and principles used to distinguish correct (good) from incorrect (bad) reasoning. He went further to describe it as the science of the laws of thought and the science of reasoning. It is glaring from the foregoing that logical processes and activities are purely mental enterprise. Such activities are not only limited to the principles that produce them but rather involve the practices of the principles in producing logical reasoning. Thus logic is not only science of reasoning as Copi posited but it also includes the art of valid reasoning. 34 Principles and Nature of Logic Logic as earlier defined by Copi I.M (1982), involves the method and principles used in distinguishing between good correct reasoning and bad incorrect reasoning. By implication, the nature and principle of logic revolves around the detection of correct or incorrect forms of reasoning, judgement and arguments as well as to show how and when they are valid or invalid. This further corroborated by Lacey A. R. who says Logic deals with valid reasoning, its systematisation and the study of notions relevant to it. This explains why he divides logic into Formal logic and Philosophical logic or logical theory. Formal logic on the one hand, is governed and guided by established and formulated rules and methods which are capable of forestalling the errors, that most often than not characterised the informal and unanalyzable logic. Formal logic is based on rules and method which are formulated to accelerate and enhance correct reasoning. Such rules include: symbolization, laws of thought, rules of inference, rules of replacement, and rules of quantification among others. While Aristotle was said to be the first scholar to come up with forms of reasoning translated to formal logic, Gettlob Frege, Bertrand Russell and Alfred-Whitehead among others have brought about great development in this area. Philosophical logic or logical theory on the other hand is what I will here refer to as informal logic. It involves the mental activity of natural capacity and disposition to think and to engage in deep reflection without following a set of rules. The assertion by Aristotle that “man is a rational animal” is very handy here as it will imply that man is naturally capable of reflection. Also, Rene Descartes’ position that “to think is to exist” shows that reasoning and reflection is an essential attribute of man. That is why logic is an essential tool of the philosopher which guides him in reasoning, investigation and provision of rational explanation to the world and human general experiences. The corollary from the forgoing demonstrates the following concerning the nature of logic: -Logic can either be formal or informal; -Logic deals with orderly reasoning and thought (thinking); -Logic concerns the order and form of arguments; -Logic process the process of arriving at judgements; -Logic deals with validity of arguments; -Logic is a mental activity; -Logic relates to thought; hence it is the activity of rational human beings. 35 Purpose of Logic Logic from what has been hitherto enunciated is necessary for many aspects of human life and society if there will be serenity, sagacity and validity in our endeavours. Among many other things, logic serves the following importance: 1. Through logic, man’s susceptibility to error in reasoning is halted. 2. Human capacity for clear and concise expression of ideas is improved. 3. Logic brings to one’s consciousness the ambiguity of words and various functions of language. 4. Its study facilitates cordial communication among people inspite of varieties in upbringing and background. 5. Training in logic is a reliable means of conflict resolution and to ensure peaceful co-existence’ 6. The study of logic is significant for meaningful deliberation and decision making especially in this era of democratic processes and institutions. 7. Logic is very invaluable in the sphere of public relation, business promotion, corporate profiles and general harmony. 8. Through the help of logic, we are awoken to the distinction between mere emotional appeal or persuasion and minority pressure. 9. Logic builds and brightens our capability for: a) formulation of rigorous argument; b) critical analysis of argument; and c) enablement for testing the correctness of all kinds of reasoning. 10. Logic promotes dispassionate rejection and correction of assumptions and presuppositions that form the foundation of positions and conclusions in other fields. From the foregoing, it is crystal clear that logic is the power of philosophy through which the entire philosophical project is carried out. Philosophers poke their noses into all aspects of science and society. In order to do this, they must possess the essential logical skills, that is, ability to analyse complex issues logically and conceptually and the ability to document their conclusions in clear and persuasive language. Such skills are not entirely innate but require intensive training in logic for their full expression. This introduction to logic and subsequent lessons that will be learnt constitutes the first professional step towards the acquisition of these skills. The link between Logic and Language Language, when carefully and correctly employed, provides enhancement and substantial support for the clarity of thought to be brought into expression. As a matter of fact, there is no logic without a lucid language of expression. Explanation, description and clarifications are brought to peoples’ understanding only when we learn to use apposite words and language to express them. Thus, there is an inseparable link between human thought/reason and language 36 for the latter is the medium of expression and visible manifestation for the former. Suffice to say then that logic performs internal functions while language functions externally. By that we mean through logic, individuals can organize, connect, and coordinate all their rational activities to become a meaningful whole. Language on the other hand enriches the meaningful expression of the thought process. In order for language to fully and clearly express what is in the thought, it performs certain functions which include: Functions of language a) Informative function, that is, when it is used to pass information or present argument; b) Expressive function which involve arousing of feelings and emotions, stating of beliefs or a conviction; c) Directive function of language is seen when it is used to cause or prevent overt action. LAWS OF THOUGHT These laws of thought which are also referred to as principles of thought do not operate in vacuum rather they operate in human daily arguments and propositions. They are three in number, viz: 1) Law of Identity 2) Law of non-Contradiction 3) Law of Excluded Middle; and they have been said to be necessary for good and correct reasoning to be achieved. 1. The Law of Identity: This law states that “what is, is what is” and nothing more. It does not give consideration to any form of change. For instance, if anything is “A” then it is “A”. It has the form of symbol P ↄ P. It asserts the truth of propositions and affirms its identity with itself such that: a school is a school and not a supermarket; a man is a man and not a bird, an aircraft is an aircraft and not a bicycle. As seemingly commonsensical this principle may seem, it has been found wanting of putting the possibility of change into consideration. Change is said to be the only permanent and constant thing in nature, hence a thing might be true under a particular condition and turn out to be different elsewhere. 2. The Law of Non-Contradiction: This law states that something cannot be both true and false at the same time. A proposition cannot be both “A” and “not A”, symbolised as “A. ~A”. It is another way of saying that a thing cannot be and at the same time not be. For example, this law does not permit me to say Mr. Babatuyi is the lecturer for this course and at the same time he is not the lecturer for the course. 3. The Law of Excluded-Middle: This law states that there can be no middle position between certain relational terms concerning truth and falsity hence; it is either a statement/ proposition 37 is true or false. It implies that we can either have it that God exist or does not exist, period! A student is either present in school or absent. And if he is present, then he is present but if he is not present, he is not present. It is either “A or not A” symbolized as A v ~A Study Questions 1. What is the different between formal and informal logic? 2. Outline the basic nature of logic 3. Why do you think logic is necessary? 4. List the three functions of language you know 5. What is the relationship between logic and language? 6. What are the fundamental laws of thought? 7. What are the problems with the laws of thought? 38 MODULE 5: ARGUMENTS AND FALLACIES Introduction Here the student will learn how to acquire and evaluate truths, criticize arguments, recognize inconsistencies and detect logical fallacies. It helps you to reason more carefully and to think and act more rationally. Objectives: - To introduce students to the art and act of logical argumentation - To provide guidelines for detecting and avoiding errors in reasoning - To equip students with the wherewithal needed for rational and careful thought process. - To protect students from winning or losing arguments by learning to detect possible fallacies NATURE OF ARGUMENT An argument is a set of statements, one of which is called the conclusion and it is affirmed on the basis of others called premises. Premises are meant to support conclusions. Of course, going by the lexical definition, to argue means: a) to give reason (for and against a proposal, etc); b) to have disagreement; quarrel- debate; c) to try to prove by giving reasons - contend; d) to give evidence of – indicate; e) to persuade into or out of an opinion by giving reasons. Put differently, an argument lexically can mean any of the following: reason(s) offered for or against something; the offering of such reason(s) otherwise called reasoning; discussion that involve disagreement, dispute, debate; and a short statement of subject matter, summary. However, in the technical sense that a logician will talk about argument, it is a series of statements or progression of propositions, where support(s) is supplied to a statement from other statement(s); while the supporting statement(s) is/are called premise(s), the supported is referred to as the conclusion. This is a clear departure from the ordinary conception of argument. Every argument in logic has two connected and related parts; one is the premise and the other is conclusion. The former always provide enough grounds for the latter to be inferred. For every correctly formulated argument therefore, there are two major components. The first component is an expressed opinion, opinion or claim while the second is the evidence or 39 grounds for the claim. In essence, not every series of statement or proposition will be qualified as argument except it expresses a claim which is buttressed by evidence. Arguments of this nature enable clarity and concise order in the presentation of thought. Example: All men are good Peter is a man, Therefore, Peter is good Validity and Soundness of an argument Validity and invalidity of argument is only applicable to deductive argument. This is because deductive arguments are non-ampliative or explicative in nature. Put differently, conclusion in deductive arguments is entailed by the premisses. Validity is the logical relationship that should and must exist between the premisses and the conclusion of an argument. It is quite possible to have deductively valid argument with either true or false propositions. Therefore, when the premisses are true, the conclusion will necessarily be true and if the premisses are false, the conclusion will be false as well. Example: All Africans are members of the third world race. All Nigerians are Africans. Therefore, all Nigerians are members of the third world race. Soundness of an argument on the other hand, combines validity of an argument with truthfulness of all its propositions. Thus a sound argument is a deductively valid argument whose premisses and conclusion are true. However, if the argument is deductively valid while all its premisses and conclusion are false, then it is said to be unsound. Example: All humans are animals All animals are mortals Therefore, all humans are mortals Unsound: 40 All lecturers are professors President Buhari is a lecturer Therefore, president Buhari is a professor. Distinction between inductive and deductive inference An inference is the act of drawing conclusion from premiss(es). - In deductive inference, the premisses already provide conclusive evidence for deducing the conclusion. Inductive inference on the other hand, is probabilistic and the information deduced from the premisses is usually more than it supplies. - It is possible for the premisses in an inductive inference to be true while the conclusion is false. In deductive inference, when the premisses are true, the conclusion cannot but be true. - While inductive inferences are drawn from particular instances to general ones, deductive inferences proceed from general to particular. - The conclusion drawn through inductive inference can be disputed without any self- contradiction whereas any attempt to dispute the conclusion from a deductive inference will be logically contradictory. - One can talk of validity and invalidity in deductive inference but not in an inductive inference. FALLACIES A fallacy is an error or unsoundness in reasoning. In logic, a fallacy is the violation of set rules of valid inference. Basically, logicians classify fallacies into two, namely formal fallacies and informal fallacies. Formal fallacies are errors in formal reasoning that depend on the formal structure of an argument. Here, the premises fail to justify or support the conclusion. There are two forms of this that shall be examine below: 1. The fallacy affirming the consequent is a formal fallacy. Example: If nepotism is wrong, then it is destructive. Nepotism is destructive. Hence, nepotism is wrong. (If A, then B; B; so, A.) 2. The fallacy of denying the antecedent is another formal fallacy. Example: 41 If being friendly makes a politician good, then Dr. Okeke is a good politician. Unfortunately, being friendly does not make a politician good. So, Dr. Okeke is not a good politician. (If A, then B; not A; so, not B.) The above arguments are clear examples of violation of the valid rule of the forms a valid argument should take. Hence, a formal fallacy is said to be committed. Informal fallacies on the other hand, are fallacies which do not depend on the form or structure of an argument but on the content or facts of the argument. They are in different categories which shall be examined one after the other. 1. Fallacies of Irrelevant Premises a. Argument against the Person (argumentum ad hominem); instead of providing rational criticism of an argument or statement, one attacks the person who advances the argument or asserts the statement. It is in three forms: abusive, circumstantial and tuquoque varieties respectively. The abusive variety involves a direct personal attack on the person, e.g. an allegation that an arguer has a moral flaw which does not justify his argument. The circumstantial variety discredits an argument because it calls attention to the circumstances or situation of those who advance it. For e.g. “Okonjo Nweala argues in favour of equal pay for equal work since it is unjust to pay a person more for doing the same job just because he is male or an American. Anyway Okonjo Nweala is a black Nigerian woman, so she can argue in that manner. Such an argument should not be taken seriously.” Tuquoque charges the opponent with hypocrisy or inconsistency, e.g. “Dad says I should not lie. He says lying is wrong because it makes people distrust you. But I have heard dad lie on some occasion.” b. The Straw Man Fallacy; the claim that a statement is false on the basis that a misinterpretation of it is false. For e.g. “Abu advocates the legalization of abortion. If abortion is legalized, I can assure you that women would cease giving birth to babies. So I disagree with Abu’s opinion.” c. Appeal to Force (argumentum ad baculum); the attempt to defend a conclusion by threatening the well-being of those who do not accept it. For e.g. “Amina, you helped our firm to sell eight baskets of tomatoes and you said you are entitled to 50% of the sale. However, the manager says you are entitled to only 20%. Unless you agree with the manager, you may lose your job.” d. Appeal to the People (argumentum ad populum); the attempt to persuade a person or group by appealing to the desire to be accepted or valued by others. E.g. “You can be certain 42 of free education for all Nigerians if you vote our party into power come 2019. I can also assure you that there will be bridges connecting Lafia and Abuja. The 100% increment in salary promised by the past administration will also be fulfilled for all civil servants.” e. Appeal to Pity (argumentum ad misericordiam); the attempt to support a conclusion merely by evoking pity in one’s audience when the statements that evoke the pity are logically unrelated to the conclusion. E.g. “My sister called me this morning that my dad in London had serious headache that was why I came late to the classroom.” f. Appeal to Ignorance (argumentum ad ignorantiam); the claim that a statement is true because it has not been proven false and vice versa.E.g. “After fifty years, no one has been able to prove that existence of witchcraft. Therefore, it does not exist.” 2. Fallacies of Ambiguity They arise from double meanings or from confusion between two closely related concepts. a. Equivocation: an inference that is invalid because of its dependence on an ambiguous word or phrase. E.g. “The earth is round. Therefore, roundness is identical with the earth.” b. Amphiboly: an inference that is invalid because of its dependence on an ambiguity that is due to sentence structure. E.g. “Nietzsche wrote a book that suggests that God is dead. It is better not to read his books.” c. Composition: an invalid inference from the nature of the parts to the nature of the whole, or from the nature of the members to the nature of the group or collective. E.g. “Each part of a car is very light, therefore, a car is light.” d. Division: an invalid inference from the nature of the whole to the nature of the parts, or from the nature of the group or collective to the nature of the members. E.g. “A car is heavy, therefore each part is heavy.” 3. Fallacies of Unwarranted Assumptions a. Begging the Question (petition principii): to assume that a point has been proved. b. Appeal to Unreliable Authority (argumentum ad verecundiam): appealing to an authority when the reliability of that authority may reasonably be doubted; to assume without sufficient warrant. E.g. “According to Prof. Wole Soyinka, much intake of sugar causes diabetes.” c. False Dilemma: using a premise that unjustifiably reduces the number of alternatives to be considered. E.g. “Since you don’t have the teacher you like, you have to like the teacher you have.” d. False Cause Fallacy: consists in illegitimately assuming that one possible cause of a phenomenon is a cause although reasons are lacking for excluding other possible causes. E.g. 43 “Since I started teaching logic, students have been doing very well in the subject. It means the previous lecturer did not teach very well.” e. Fallacy of Complex Question: asking a question that illegitimately presupposes some conclusion alluded to in the question. E.g. “How many were you when you were caught jumping the fence?” Study Questions 1. Is an argument different from inference? 2. How is a formal fallacy different from an informal fallacies? 3. What are fallacies of ambiguity? 4. Identify example of fallacies of irrelevant conclusion 5. What are the differences between inductive and deductive inference? 6. When is an argument said to be valid, invalid, sound and unsound? 7. Can we have a valid inductive argument? 44 MODULE 6: SYMBOLIC LOGIC Introduction: Apart from logical engagement with issues and materials in an informal way and with natural language, there are established rules which are used in analyzing arguments. This set out rules expressed with the use of logical symbols, variables and connectives helps the level of precision and accuracy in evaluation of arguments. This module shall hence concentrate on introducing students to basic symbols and connectives use in formal or symbolic logic. Objectives: - To enable students achieve precision in evaluating arguments - To introduce students to rudiments of symbolic logic - To equip students with mathematical tool for thought analysis What is symbolic Logic?  Symbolic logic is the method of representing logical expressions through the use of symbols and variables, rather than in ordinary language. This has the benefit of removing the ambiguity that normally accompanies ordinary languages, such as English, and allows easier operation.  There are many systems of symbolic logic, such as classical propositional logic, first- order logic and modal logic. Each may have seperate symbols, or exclude the use of certain symbols.  In symbolic logic, propositions and arguments are analysed using symbols and variables.  It is important to know that logicians deal more with propositions in vthe analysis of thought rather than dealing with sentences or semantic of expression as do the grammarians. Propositions Proposition/ Statement - a statement is a sentence that is either true or false. It is different from a sentence even though it is the very thought conveyed through sentences. Truth and falsehood are the two possible truth values. Statements are therefore sentences that have truth values. 45 Example: All Mobile phones have bluetooth. Not all Mobile phones have cameras. Types of Propositions 1. Simple proposition: This kind of proposition expresses a sing thought. It is usually a statement with a subject term and a predicate term. This is also called an atomic proposition. Example: The Vice-Chancellor is in the office. 2. Compound proposition: This is a kind of proposition containing other propositions within itself in that each of those propositions can stand independently of each other. Example: - Dr. Haaga bought a baby walker yesterday, came to my residential house and gave the gift of a baby walker to my daughter. 3. Disjunctive propositions: In this type of proposition, there two alternating components but no one of its component parts is asserted. It is also called Alternation. Example: Either Atiku Abubakar or Mohamad Buhari will win the next presidential election 4. Hypothetical propositions: This is also known as conditional proposition. There are two components in such propositions but one serves as the cause whilst the other is the effect. It usually introduce with use of “if-then”. Example: If there is no God, then we are all products of natural causes. It is worthy of note that no single proposition is an argument because an argument is a group of propositions. Although every argument is a structured cluster of propositions, not every structured cluster of propositions is an argument; “every law is evil, for it is an infringement of liberty. 46 Logical constants and sentential connectives In an earlier explanation, a compound proposition is said to be made up of simple propositions that were joined together with the use of connective words. In order to derive an apt and precise compound statement from two or more simple statements, there is need to make use of some connecting words or phrases. These connecting words or phrases are technically called logical constants, sentential connective or logical participles. According to Akinnawonu, logical constants perform two major functions in prepositional logic (Akinnawonu, 2006: 215). These are as follows: 1. Logical constants serve as connecting words or phrases, as such, they are referred to as sentential connectives. 2. Logical constants help to determine the truth value of the compound statements that they help to form. Hence, they are referred to as Truth-functional sentential connectives. FIVE MAJOR LOGICAL CONNECTIVES Names Words Symbols 1. Conjunction ‘and’ (dot) 2. Negation ‘not’ ~ (tilde) 3. Disjunction ‘either … or...’ V (vel) 4. Material implication ‘if … then …’  (horse shoe) 5. Material Equivalence ‘if and only if’ ≡ /  (bi conditional) The following examples correspond with each of the five logical constants above: 1. The righteous is reigning and the people are rejoicing. 2. The righteous is not reigning. 3. Either the righteous is reigning or the people are rejoicing. 4. If the righteous is reigning then the people are rejoicing 5. The righteous is reigning if and only if the people are rejoicing. (Okeke is a bachelor if and only if he is an unmarried male) 47 Let us attempt a symbolism of the above compound statements. Variables ‘p’ and ‘q’ can be used to represent the statements “the righteous is reigning”, and “the people are rejoicing” respectively. The various statements are thus symbolized below where it is assumed that ‘p’ and ‘q’ are standing correspondingly for the two components of the earlier stated compound propositions: (1) p q (where the dot represents ‘and’) (2) ~ p (where tilde represents ‘not’) (3) p v q (where vel represents ‘either…or’) (4) p  q (where the horse shoe represents ‘if, then’) (5) p  q or p  q (where the bi-conditional sign represents ‘if and only if’) Study Questions 1. What is symbolic logic? 2. Enumerate the five symbols and their respective names 3. Discuss the types of propositions you know with relevant examples 4. What is the difference between sentence and proposition? 5. This symbolisation “B ≡ S” implies _____? 6. (B ͻ S) (S ͻ B) can be a symbolism for which proposition? 7. (B S) ͻ (S B) is an example of material implication. True or False? 48 MODULE 7: TECHNIQUES FOR EVALUATING ARGUMENT Introduction The primary preoccupation of logic is evaluating arguments in order to ascertain its validity or otherwise. In doing this, different techniques have been devised over the years by logicians. They include: The Truth-table method; the use of Venn diagrams; Rules of inference and rules of replacement among others. This module will address and dwell more an analysing argument with use of elementary valid argument rules. Objectives - to make students understand what the nine rules stand for and how they are used - to enable students learn the practice of symbolising arguments and determining their validity at a glance - to ensure students understand the basic possible combination and manipulation of rules toward successful proof of arguments. ELEMENTARY VALID ARGUMENTS/RULES OF INFERENCES There are nine of the elementary valid rules which can be invoked in proving the validity of an argument. These rules have been already established to be valid and any argument that takes their form will automatically valid whilst any one that fails to conform to such rule ends up committing a formal fallacy. 1. Modus Ponens (M.P) P Q P Q This rule means the mode of affirming or positing which says “given a conditional statement or an implication, and also given the antecedent of such conditional statement, we can validly infer the consequent of the conditional statement”. In other words, the truth of the antecedent of a conditional statement implies the truth of its consequent. This argument form corresponds to the following argument. If it rains then the ground is wet (p  q) It has rained. (p) 49 Therefore, the ground is wet. (:. q) Where ‘P’ stands for ‘it rains’, ‘q’ for ‘the ground is wet’. 2. Modus Tollens (M.T) PQ ~Q ~P It is called the mode of denying or the removing mode. It says, given a conditional statement, and also given the negation of the consequent of such conditional statement, one can validly infer the negation of the antecedent of the conditional statement. That is, the negation of the consequent of a conditional statement implies the negation its antecedent. Thus, this argument form corresponds to the argument below: If the earth is spherical in shape then the sun rises in the east. It is not the case that the sun rises in the east. Therefore, it is not the case that the earth is spherical in shape. Where ‘p’ stands for ‘it rains’, ‘q’ for the ground is wet’. 3. Hypothetical Syllogism (H.S) PQ QR QR This is a broad form either modus ponens or modus tollens. It says, given a conditional statement, and given another conditional statement whose antecedent is the consequent of the first conditional statement, one can validly infer a conditional statement whose antecedent is the antecedent of the first conditional statement and whose consequent is the consequent of the second conditional statement. Put differently, if there are two conditional statements where the consequent of one is the antecedent of the other, then the antecedent of the first implies the consequent of the second conditional statement. An example is demonstrated thus: If it rains then the ground is wet (p  q) If the ground is wet then the grass will grow (q  r) 50 Therefore, if it rains, the grass will grow.  (p  r) 4. Disjunctive Syllogism (D.S) PvQ ~P Q Given a disjunction, and given the negation of the first disjunct, one can validly infer the second disjunct. Put differently, in a disjunction of two statements, the denial of the first disjunct implies the truth of the second. For example, Either Okeke is a Moslem or he is a Christian Okeke is not a Moslem Therefore, Okeke is a Christian 5. Constructive Dilemma (C.D) (P  Q) (R  S) PvR QvS In a constructive dilemma, there is a given conjunction of two conditional statements, and given a disjunction of the antecedents of the two implications, one can validly infer a disjunction of the consequents of the two implications. That is, the disjunction of the antecedents implies the disjunction of the consequents of the given conditional statements. Arguments of this form always end in a disjunction of unpleasant alternatives or in a dilemma. Consider the argument below as example: If youths are allowed to reign then Nigeria will be better and if the old politicians continue to rule then there is hope for Nigeria. Either the youths are allowed to reign or the old politicians continue to rule Therefore, either Nigeria becomes better or there is no hope for Nigeria. 6. Absorption (Abs.) PQ  P  (P Q) 51 The rule says given a conditional statement, one can validly infer another conditional statement whose antecedent is the antecedent of the first implication and whose consequent is a conjunction of the antecedent and consequent of the first implication. Put differently, the antecedent of a conditional statement implies the conjunction of both the antecedent and the consequent. For example: If Isaiah has been called to bar then he is a law graduate Therefore, if Isaiah has been called to bar then he has been called to bar and he is a law graduate. 7. Simplification (Simp.) P Q P This rule is also called ‘elimination’ which allows one to conclude with the first conjunct of a conjunction. It says, given a conjunction, one can validly infer the, first conjunct. For example: Haaga is a lecturer and Negedu is a lawyer Therefore, Haaga is a lecturer 8. Conjunction (conj.) P Q P Q Given an atomic statement, and given another atomic statement, one can validly infer a conjunction of the two statements, thereby forming a molecular statement. It is a rule that allows two single propositions to be validly made one conclusion. The earth is spherical in shape The sun rises in the east Therefore, the earth is spherical in shape and the sun rises in the east. 9. Addition (Add.) P P v Q 52 Given an atomic statement, one can validly infer a disjunction of that statement and any other one. It is also called the rule of ‘v-introduction’ Ojomah is a disciplinarian Therefore, either Ojomah is a disciplinarian or Besong is an activist TIPS ON APPLICATION OF THE NINE RULES Applying the nine rules could be somewhat tactical hence it requires some bits of ingenuity. It can however be simply approached by bearing in mind, at every point, the need to arrive at the already provided conclusion of the argument whilst supplying the missing premises. The following tips will be of help to anyone who attempt to prove the validity of any given argument: 1. What kind of overall statement is the conclusion? Is it a conjunction or disjunction, etc? 2. Does the conclusion appear as a whole in any of the premises? 3. If question (2) is affirmative, then we may go on to ask in what statement the conclusion appears? 4. If the conclusion appears in disjointed form, one may ask by what rule one can bring its parts together? In what follows, attempt shall be made to construct a proof of validity for some selected arguments with the aid of the nine rules of inference outline above. That which is found cited by the right hand side of each line of the premises after the given conclusion is known as the justification for each inference. The process always continues until the conclusion is finally established. Example 1 1. P  Q 2. P R / Q 3. P 2, Simp. 4. Q 1, 3 MP 53 Example 2 1. Q  R 2. ~S  (T  U) 3. S v (Q v T) 4. ~S /R v U 5. T  U 2, 4, MP 6. (Q  R) (T  U) 1, 5, Conj. 7. Q v T 3, 4, DS 8. R v U 6, 7, CD, Simp. Example 3 1. A  B 2. A 3. B v C / A B 4. A  (A.B) 1, Abs. 5. A B 4, 3, M.P Study Questions Symbolize the following arguments and test for validity with the aid of the nine rules of inferences. 1. Either Dr. Ojomah is a pastor or he is a lecturer. Dr. Ojomah is not a pastor. Therefore, Dr. Ojomah is a lecturer. (P, L) 2. If Professor Dugga is a good Christian, then Professor Dugga upholds good moral principles. If Professor Dugga upholds good moral principles then he is a light of the world. It is the case that Professor Dugga is a good Christian. Hence, Professor Dugga is a good Christian and upholds good moral principles. (C, M, L). 54 3. Either Mr. Aduragbemi is a sadist or he is a disciplinarian. It is not the case that Mr. Aduragbemi is a sadist. Consequently, either Mr. Aduragbemi is a disciplinarian or he is a philosopher. (S, D, P) 4. If FULafia is a new university then it is not a first generation university. All new universities are federal universities. FULafia is a new university. Certainly, FULafia is a federal university. (N, G, F) Each

GST 123: Philosophy and Logic Module - Federal University Lafia PDF

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