Logic and Critical Thinking PDF

Logic and Critical Thinking STEPHEN L. CAGURANGAN, LPT INSTRUCTOR  INTRODUCTION Logic and critical thinking are intertwined intellectual disciplines that shape how individuals reason, solve problems and make decisions. They provide frameworks for evaluating arguments, un...

Logic and Critical Thinking STEPHEN L. CAGURANGAN, LPT INSTRUCTOR  INTRODUCTION Logic and critical thinking are intertwined intellectual disciplines that shape how individuals reason, solve problems and make decisions. They provide frameworks for evaluating arguments, understanding the world more clearly, and approaching complex issues in a structured and thoughtful manner. By honing these skills, individuals develop the ability to navigate a variety of scenarios with clarity, objectivity, and precision. LESSON 1: MEANING AND NATURE OF PHILOSOPHY Do you have a prior awareness of philosophy? If so, how do you understand philosophy? _________________________________________________________ _________________________________________________________ ______________________________________________________ Socrates once stated that “Wonder is the feeling of a philosopher, and philosophy begins in wonder”.  What is Philosophy? The word "philosophy" comes from the Greek word "philosophia," which is a combination of two Greek words: "philo," meaning "love," and "sophia," meaning "wisdom" or "knowledge." Therefore, the etymological meaning of philosophy is "love of wisdom" or "the pursuit of knowledge and wisdom." In ancient Greece, philosophers were considered to be individuals who loved knowledge and wisdom, and they were highly respected for their intellectual pursuits.  Pythagoras was the first to use the word “philosopher” to call a person who clearly shows a marked curiosity in the things he experiences. Seeking wisdom is among the various essences of philosophy that it has got from its etymological definition. Nevertheless, this is not sufficient by itself to understand philosophy, for not all wisdoms are philosophy. What do you think is the wisdom that philosophers seek? _____________________________________________________________ _____________________________________________________________.  The wisdom that philosophers seek is not the wisdom of the expertise or technical skills of professionals. According to Socrates, wisdom consists of a critical habit and eternal vigilance about all things and a reverence for truth, whatever its form, and wherever its place. Based on the Socratic understanding of wisdom, philosophy, as a pursuit of wisdom, is, thus, the development of critical habits, the continuous search for truth, and the questioning of the apparent. Questioning/criticism is not the final end of philosophy, though raising the right question is often taken not only as the beginning and direction of philosophy but also as its essence. Raising the right question is an art that includes the ability to foresee what is not readily obvious and to imagine different possibilities and alternatives of approaching the apparent.  The philosophical enterprise, as Vincent Barry stated, is “an active imaginative process of formulating proper questions and resolving them by rigorous, persistent analysis”. The essence of what philosophy is all about: it’s an active, creative, and analytical process. 1. Active Imaginative Process: Philosophy is not a passive or static activity. It requires active thinking, curiosity, and creativity. Philosophers need to use their imagination to come up with new, important, and insightful questions about the world and human experience. 2. Formulating Proper Questions: Philosophy often starts by asking the right questions—questions that may not have easy answers but are important for understanding the nature of life, morality, reality, and knowledge. These questions guide philosophical inquiry. 3. Resolving by Rigorous, Persistent Analysis: Once the right questions are formulated, philosophers engage in rigorous (careful and detailed) and persistent (continuing over time) analysis. They evaluate different ideas, challenge assumptions, and critically examine arguments to come to a deeper understanding or to find a solution.  BASIC FEATURES OF PHILOSOPHY 1. Philosophy is a set of views or beliefs about life and the universe, which are often held uncritically. 2. Philosophy is a process of reflecting on and criticizing our most deeply held conceptions and beliefs. 3. Philosophy is a rational attempt to look at the world as a whole. 4. Philosophy is the logical analysis of language and the clarification of the meaning of words and concepts. 5. Philosophy is a group of perennial problems that interest people and for which philosophers always have sought answers.  CORE FIELD OF PHILOSOPHY 1.Metaphysics ▪ Metaphysics is the branch of philosophy that studies the ultimate nature of reality or existence. It deal with issues of reality, God, freedom, soul/immortality, the mind-body problem, form and substance relationship, cause and effect relationship, and other related issues. ▪ The term metaphysics is derived from the Greek words “meta” means (“beyond”, “upon” or “after”) and physika, means (“physics”). Literally, it refers ‘those things after the physics.’  CORE FIELD OF PHILOSOPHY Here are some of the questions that Metaphysics primarily deals with: What is reality? What is the ultimately real? What is the nature of the ultimate reality? Is it one thing or is it many different things? Can reality be grasped by the senses, or it is transcendent? What makes reality different from a mere appearance? What is mind, and what is its relation to the body?  Is there a cause and effect relationship between reality and appearance? Does God exist, and if so, can we prove it? Are human actions free, or predetermined by a supernatural force? What is human being? A thinking mind?A perishable body? Or a combination of both? What is time? What is the meaning of life?  Metaphysical questions may be divided into four subsets or aspects. A.Cosmological Aspect: Cosmology consists in the study of theories about the origin , nature, and development of the universe as an orderly system. ex. “How did the universe originate and develop? B. Theological Aspect: Theology is that part of religious theory that deals with conceptions of and about God. ex. “Is there a God? C.Anthropological Aspect: Anthropology deals with the study of human beings ex. What is the relation between mind and body? D. Ontological Aspect: Ontology is the study of the nature of existence, or what it means for anything to exist. ex. “Is basic reality found in matter or physical energy (the world we can sense), or is it found in spirit or spiritual energy?  2. Epistemology Epistemology is the other field of philosophy that studies about the nature, scope, meaning, and possibility of knowledge. It deals with issues of knowledge, opinion, truth, falsity, reason, experience, and faith. Epistemology is also referred to as “theory of knowledge”. Etymologically, the word epistemology has been derived from the Greek words episteme, meaning “knowledge, understanding”, and logos, meaning “study of ”. The following are among the questions/issues with which Epistemology deals: What is knowledge? What does it mean to know? What is the source of knowledge? Experience? Reason? Or both? How can we be sure that what we perceive through our senses is correct? What makes knowledge different from belief or opinion? What is truth, and how can we know a statement is true?  Can reason really help us to know phenomenal things without being informed by sense experiences? Can our sense experience really help us to know things beyond our perception without the assistance of our reasoning ability? What is the relationship and difference between faith and reason?  ❑ Skepticism in its narrow sense is the position claiming that people cannot acquire reliable knowledge and that any search for truth is in vain ❑ Agnosticism is a profession of ignorance in reference to the existence or nonexistence of God. Sources of Human Knowledge 1. Emperical knowledge - empiricism (knowledge obtained through the senses 2. Rationalism- reasoning, thought, or logic 3. Intuition- occurs beneath the threshold of consciousness and is often experienced as a sudden flash of insight. 4. revelation- presupposes a transcendent supernatural reality 5. authority.- comes from experts or has been sanctified over time as tradition 3. Intuition- occurs beneath the threshold of consciousness and is often experienced as a sudden flash of insight. 4. Revelation- presupposes a transcendent supernatural reality 5. Authority.- comes from experts or has been sanctified over time as tradition  3. Axiology Axiology is the study or theory of value. The term Axiology stems from two Greek words- “Axios”, meaning “value, worth”, and “logos”, meaning “reason/ theory/ symbol / science/study of ”. Hence, Axiology is the philosophical study of value, which originally meant the worth of something. Axiology asks the philosophical questions of values that deal with notions of what a person or a society regards as good or preferable, such as: What is a value? Where do values come from? How do we justify our values? How do we know what is valuable? What is the relationship between values and knowledge? What kinds of values exist? Can it be demonstrated that one value is better than another?  Who benefits from values?  4. Ethics Ethics, which is also known as Moral Philosophy, is a science that deals with the philosophical study of moral principles, values, codes, and rules, which may be used as standards for determining what kind of human conduct/action is said to be good or bad, right or wrong. Ethics raises various questions including: What is good/bad? What is right/wrong? Is it the Right Principle or the Good End that makes human action/conduct moral? Is an action right because of its good end, or it is good because of its right principle? Are moral principles universal, objective, and unconditional, or relative, subjective and conditional? What is the ultimate foundation of moral principles? The supernatural God? Human reason? Mutual social contract? Social custom? Does God exist? If so, is He Benevolent and Omnipotent?  3 Main Branches 1.Normative Ethics refers to the ethical studies that attempt to study and determine precisely the moral rules, principles, standards and goals by which human beings might evaluate and judge the moral values of their conducts, actions and decisions. 2. Meta-ethics is the highly technical philosophical discipline that deals with investigation of the meaning of ethical terms, including a critical study of how ethical statements can be verified. 3. Applied Ethics is a normative ethics that attempts to explain, justify, apply moral rules, principles, standards, and positions to specific moral problems.  Aesthetics Aesthetics is the theory of beauty. It studies about the particular value of our artistic and aesthetic experiences. It deals with beauty, art, enjoyment, sensory/emotional values, perception, and matters of taste and sentiment. The following are typical Aesthetic questions: What is art? What is beauty? What is the relation between art and beauty? What is the connection between art, beauty, and truth? Can there be any objective standard by which we may judge the beauty of artistic works, or beauty is subjective? Does art have any moral value, and obligations or constraints? Are there standards of quality in Art?  BASIC CONCEPTS OF LOGIC: ARGUMENTS, PREMISES AND CONCLUSIONS People use words like "logic" and "logical" a lot, often without really understanding what they mean.  o The word logic comes from Greek word logos, which means sentence, discourse, reason, truth and rule. Logic is a science that helps to develop the method and principles that we may use as a criterion for evaluating the arguments of others and as a guide to construct good arguments of our own. Logic is a science that evaluates arguments. Logic is the study of methods for evaluating arguments. More precisely, logic is the study of methods for evaluating whether the premises of arguments adequately support or provide a good evidence for the conclusions. Logic is the attempt to codify the rules of rational thought. Logicians explore the structure of arguments that preserve truth or allow the optimal extraction of knowledge from evidence. Logic is one of the primary tools philosophers use in their inquiries. The precision of logic helps them to cope with the subtlety of philosophical problems and the often misleading nature of conversational language.  WHAT IS ARGUMENT? Argument is a technical term and the chief concern of logic. Arguments from logical point of view, it is a group of statements, one or more of which (the premise) are claimed to provide support for, or reason to believe, one of the other, the (conclusion). ❖ First, an argument is a group of statements What is a statement? A statement is a declarative sentence that has a truth-value of Example # 1 either true or false a) Dr. Abiy Ahmed the current Prime Minister of Ethiopia. b) Mekelle is the capital city of Tigray Region. c) Ethiopia was colonized by Germany.  ❖Second, the statements that make up an argument are divided into premise(s) and conclusion. Hence, an argument is a group statement, which contains at least one premise and one and only one conclusion Argument always attempts to justify a claim. The claim that the statement attempts to justify is known as a conclusion of an argument; and the statement or statements that supposedly justify the claim is/are known as the premises of the argument ✓ Premise- is a statement that set forth the reason or evidence, which is given for accepting the conclusion of an argument ✓ Conclusion is a statement, which is claimed to follow from the given evidence.  Example-1: 1)All Ethiopians are Africans. (Premise 1) Tsionawit is Ethiopian. (Premise2) Therefore, Tsionawit is African. (Conclusion) Example-2: 1)Some Africans are black. (Premise-1) Zelalem is an African. (Premise-2) Therefore, Zelalem is black. (Conclusion)  But how can we distinguish premises from conclusion and vice versa? The first technique that can be used to identify premises from a conclusion and vice versa is looking at an indicator word. Frequently, arguments contain certain indicator words that provide clues in identifying premises and conclusion. Here below are some Conclusion Indicators: Therefore Entails that We may infer Wherefore Hence It implies that Accordingly It shows that Provided that As a result Whence It must be that So Thus We may Consequently It follows that conclude  Here below are some typical Premise Indicators: Since Seeing In that As that May be inferred indicated by Given that from Because As Inasmuch as Owing to For For the reason that  Techniques of Recognizing Arguments Not all passages contain argument. a passage contains an argument if it purports to prove something; if it does not do so, it does not contain an argument. But what does it mean to purport to prove something? Two conditions must be fulfilled for a passage to purport to prove something: 1) At least one of the statements must claim to present evidence or reasons. 2) There must be a claim that the alleged evidence or reasons supports or implies something- that is, a claim that something follows from the alleged evidence. The first condition expresses a factual claim. The second condition expresses what is called an inferential claim. explicit or implicit  Recognizing Non-argumentative Passages ❑ Simple non-inferential passages are unproblematic passages that lack a claim that anything is being proved. PASSAGES OF THIS SORT INCLUDE: 1. A warning is a form of expression that is intended to put someone on guard against a dangerous or detrimental situation. Example: Whatever you promise to tell, never confide political secrets to your wife. PASSP  2. A piece of advice is a form of expression that makes a recommendation about some future decision or course of conduct. Example: After class hours, I would suggest that you give careful consideration to the subject matter you have discussed.. 3. A statement of belief or opinion is an expression about what someone happens to believe or think about something. Example: We believe that our university must develop and produce outstanding students who will perform with great skill and fulfill the demands of our nation.  4. Loosely associated statements may be about the same general subject, but they lack a claim that one of them is proved by the others. Example: Not to honor men of worth will keep the people from contention; not to value goods that are hard to come by will keep them from theft; not to display what is desirable will keep them from being unsettled of mind. (Lao-Tzu, Thoughts from the Tao Te Ching) 5. A report consists of a group of statements that convey information about some topic or event. Example # 1: The great renaissance dam of Ethiopia has opened an employment opportunity for thousands of Ethiopians. In its completion, thirteen thousand Ethiopians are expected to be hired.`  Example # 2: “The Air Force faces a serious shortage of experienced pilots in the years ahead, because repeated overseas tours and the allure of high paying jobs with commercial airlines are winning out over lucrative bonuses to stay in the service,” says a prominent Air Force official. (Newspaper clipping) ❑Expository Passages An expository passage is a kind of discourse that begins with a topic sentence followed by one or more sentences that develop the topic sentence. If the objective is not to prove the topic sentence but only to expand it or elaborate it, then there is no argument  Example: There is a stylized relation of artist to mass audience in the sports, especially in baseball. Each player develops a style of his own-the swagger as he steps to the plate, the unique windup a pitcher has, the clean-swinging and hard-driving hits, the precision quickness and grace of infield and outfield, the sense of surplus power behind whatever is done. (Max Lerner, America as a Civilization) ❑ Illustrations An illustration is an expression involving one or more examples that is intended to show what something means or how it is done. Illustrations are often confused with arguments because many illustrations contain indicator words such as “thus.” Example: Chemical elements, as well as compounds, can be represented by molecular formulas. Thus, oxygen is represented by “O2”, water by “H2O”, and sodium chloride by “NaCl”. ❑ Explanations One of the most important kinds of non-argument is the explanation. An explanation is an expression that purports to shed light on some event or phenomenon, which is usually accepted as a matter of fact. It attempts to clarify, or describe such alike why something is happen that way or why something is what it is. Example: Cows digest grass while humans cannot, because their digestive systems contain enzyme not found in humans.  Every explanation is composed of two distinct components: A. Explanandum is the statement that describes the event or phenomenon to be explained. B. Explanans is the statement or group of statements that purports to do the explaining. In the first example, the explanandum is the statement ❑Conditional Statements A conditional statement is an “if... then...” statement. The component statement immediately following the “if” is called the antecedent (if-clause), Example: If you study hard, then you will score ‘A’ grade. The one following the “then” is called the consequent (then- clause For example: if we left out “then” from the above example the antecedent and consequent is reversed: You will score ‘A’ grade if you study hard. Conditional statements are not arguments In a conditional statement, there is no claim that either the antecedent or the consequent presents evidence  Some conditional statements are similar to arguments in that they express the outcome of a reasoning process. As such, they may be said to have a certain inferential content. Example: If destroying a political competitor gives you joy, then you have a low sense of morality The conditional statement can be re-expressed to form an argument. Example: Destroying a political competitor gives you joy. Therefore, you have a low sense of morality.  While no single conditional statement is an argument, a conditional statement may serve as either the premise or the conclusion (or both) of an argument Example: If he is selling our national secretes to enemies, then he is a traitor. He is selling our national secretes to enemies. Therefore, he is a traitor. If he is selling our national secretes to enemies, then he is a traitor. If he is a traitor, then he must be punished by death. Therefore, If he is selling our national secretes to enemies, then he must be punished by death. The relation between conditional statements and arguments may now be summarized as follows: 1)A single conditional statement is not an argument. 2)A conditional statement may serve as either the premise or the conclusion (or both) of an argument. 3)The inferential content of a conditional statement may be re-expressed to form an argument.  Conditional statements are especially important in logic (and many other fields) because they express the relationship between necessary and sufficient conditions. A is said to be a sufficient condition for B whenever the occurrence of A is all that is needed for the occurrence of B. For example, being a dog is a sufficient condition for being an animal. On the other hand, B is said to be a necessary condition for A whenever A cannot occur without the occurrence of B. Thus, being an animal is a necessary condition for being a dog. On the other hand, suppose you are told that whatever might be in the box, it is not an animal. Then you know for certain there is no dog in the box. The reason you can draw this conclusion is that being an animal is necessary for being a dog. If there is no animal, there is no dog. On the other hand, suppose you are told that whatever might be in the box, it is not an animal. Then you know for certain there is no dog in the box. The reason you can draw this conclusion is that being an animal is necessary for being a dog. If there is no animal, there is no dog. However, being an animal is not sufficient for being a dog, because if you are told that the box contains an animal, you cannot, from this information alone, conclude that it contains a dog. It might contain a cat, a mouse, a squirrel, and so on. These ideas are expressed in the following conditional statements: If X is a dog, then X is an animal. If X is not an animal, then X is not a dog. In deciding whether a passage contains an argument, you should look for three things: 1) indicator words such as “therefore,” “since,” “because,” and so on; 2) an inferential relationship between the statements; and 3) typical kinds of non-arguments In many arguments that lack indicator words, the conclusion is the first statement. Furthermore, it helps to mentally insert the word “therefore” before the various statements before deciding that a statement should be interpreted as a conclusion.  Types of Arguments ❑ Deductive Arguments - A deductive argument is an argument incorporating the claim that it is impossible for the conclusion to be false given that the premises are true. It is an argument in which the premises are claimed to support the conclusion in such a way that it is impossible for the premises to be true and the conclusion false. In such arguments, the conclusion is claimed to follow necessarily (conclusively) from the premises. Thus, deductive arguments are those that involve necessary reasoning. Example-1: All philosophers are critical thinkers. Socrates is a philosopher. Therefore, Socrates is a critical thinker.  Example-2: All African footballers are blacks. Messi is an African footballer. It follows that, Messi is black. ❑Inductive Arguments An inductive argument is an argument incorporating the claim that it is improbable for the conclusion to be false given that the premises are true.. It is an argument in which the premises are claimed to support the conclusion in such a way that it is improbable for the premises to be true and the conclusion false. Example-1: Most African leaders are blacks. Mandela was an African leader. Therefore, probably Mandela was black. Example-2: Almost all women are mammals. Hanan is a woman. Hence, Hanan is a mammal.  Differentiating Deductive and Inductive Arguments 1. The occurrence of special indicator words. Example: “certainly,’’ “necessarily,” ‘‘absolutely,’’ and ‘‘definitely’’ indicate that the argument should be taken as deductive, whereas words like, “probable” ‘‘improbable,’’ ‘‘plausible,’’ ‘‘implausible,’’ ‘‘likely,’’ ‘‘unlikely,’’ and ‘‘reasonable to conclude” 2) The actual strength of the inferential link between premises and conclusion. 3) The character or form of argumentation the arguers use.  Instances of Deductive Argumentative Forms ❖ Argument based on mathematics: it is an argument in which the conclusions depend on some purely arithmetic or geometric computation or measurement Ex. You can put two orange and three bananas in a bag and conclude that the bag contains five fruits. Or again you can measure a square pieces of land and after determining it is ten meter on each side conclude that its area is a hundred square meter. ❖ Arguments based on definition: it is an argument in which the conclusion is claimed to depend merely up on the definition of some words or phrase used in the premise or conclusion. Ex. One may argue that Angel is honest; it is follows that Angel tells the truth. Or again, Kebede is a physician; therefore, he is a doctor.  ❖ Syllogisms are arguments consisting of exactly two premises and one conclusion. A. Categorical syllogism: a syllogism is an argument consisting of exactly two premises and one conclusion. Categorical syllogism is a syllogism in which the statement begins with one of the words “all”, “no” and “some”. Example: All Egyptians are Muslims. No Muslim is a Christian. Hence, no Egyptian is a Christian.  B. Hypothetical syllogism: It is a syllogism having a conditional statement for one or both of its premises. Example: If you study hard, then you will graduate with Distinction. If you graduate with Distinction, then you will get a rewarding job. Therefore, if you study hard, then you will get a rewarding job. C. Disjunctive syllogism: it is a syllogism having a disjunctive statement. (I.e. an “either … or” statement.) Example: Rewina is either Ethiopian or Eritrean. Rewina is not Eritrean. Therefore, Rewina is Ethiopian.  Instances of Inductive Argumentative Forms A. Prediction: in a prediction the premises deals with some known event in the present or the past and the conclusions moves beyond this event to some event to relative future. Ex. One may argue that because certain clouds develop in the center of the highland, a rain will fall within twenty-four hours B.An argument from analogy: It is an argument that depends on the existence of an analogy or similarity between two things or state of affairs. Because of the existence of this analogy a certain conditions that affects the better- known thing or situations is concluded to affect the less familiar , lesser known-thing or situation. Ex. one may conclude, after observing the similarity of some features of Computer A and car B: that both are manufactured in 2012; that both are easy to access; that Computer A is fast in processing; it follows that Computer B is also fast in processing.  C. An inductive generalization: it is an argument that proceeds from the knowledge of a selected sample to some claim about the whole group. Because the members of the sample have a certain characteristics, it is argued that all members of the group have the same characteristics. Ex. One may argue that because three out of four people in a single prison are black, one may conclude that three-fourth of prison populations are blacks D. An argument from authority: it is an argument in which the conclusions rest upon a statement made by some presumed authority or witness. Ex. A lawyer, for instance, may argue that the person is guilty because an eyewitness testifies to that effect under oath. Or again one may argue that all matters are made up of a small particles called “quarks” because the University Professor said so E.Arguments based on sign: it is an argument that proceeds from the knowledge of a certain sign to the knowledge of a thing or situation that the sign symbolizes. Ex. One may infer that after observing ‘No Parking’ sign posted on the side of a road, the area is not allowed for parking F. A causal inference: it is an argument which proceed from the knowledge of a cause to the knowledge of an effect, or conversely, from the knowledge of an effect to knowledge of a cause Ex. From the knowledge that a bottle of water had been accidentally left in the freezer overnight, someone might conclude that it had frozen (cause to effect). Conversely, after tasting a piece of chicken and finding it dry and tough, one might conclude that it had been overcooked (effect to cause).  Validity, Truth, Soundness, Strength, Cogency ❖ A Valid Argument is a deductive argument in which, if the premises are assumed true, it is impossible for the conclusion to be false. In such arguments, the conclusion follows with strict necessity from the premises. For example; All birds are mammals. A crocodile is a bird. Therefore, the crocodile is a mammal.  Here is an example of valid argument having a false premise and false conclusion: All auto makers are computer manufacturers; NOKIA is an auto maker. Therefore, NOKIA is a computer manufacturer. ❖An Invalid Argument is a deductive argument such that if the premises are assumed true, it is possible for the conclusion to be false. In these arguments the conclusion does not follow with strict necessity from the premises, even though it claimed to. All banks are financial organizations. Nyala Insurance Company is a financial organization. Therefore, Nyala Insurance Company is a bank. ❖ A Sound Argument is a deductive argument that is valid and has all true premises. Both conditions must be met for an argument to be sound, and if either is missing the argument is unsound. For example: All trees are plants. Acacia is a tree. Therefore, acacia is a plant. ❖ Unsound Argument is a deductive argument that is invalid, has one or more false premises, or both ❖A Strong Argument is an inductive argument such that if the premises are assumed true, then based on the assumption it is probable that the conclusion is true. Ex. This mini-library contains over 10,000 books. 1000 books selected at random were found to be written on philosophy. Thus, it is likely that all of the books in the minilibrary are books written on philosophy. (Strong Inductive Argument) ❖A weak Argument is an inductive argument such that if the premises are assumed true, then based on that assumption it is not probable that the conclusion is true. Examples: This mini-library contains over 10,000 books. 50 books selected at random were found to be written on philosophy. Thus, it is likely that all of the books in the minilibrary are books written on philosophy. (Weak Inductive Argument. THANK YOU