Topic 2 - Epistemology (Foundation of Scientific Knowledge) PDF

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 G. Gobo, V. Marcheselli, Science, Technology and Society https://doi.org/10.1007/978-3-031-08306-8_3 3. Epistemology: The Foundations of Scientific Knowledge Giampietro Gobo1 and Valentina Marcheselli2 (1) Department of...

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 G. Gobo, V. Marcheselli, Science, Technology and Society https://doi.org/10.1007/978-3-031-08306-8_3 3. Epistemology: The Foundations of Scientific Knowledge Giampietro Gobo1 and Valentina Marcheselli2 (1) Department of Philosophy, University of Milano, Milano, Italy (2) Department of Sociology and Social Research, University of Trento, Trento, Italy Keywords Epistemology – Neopositivism – Popper The word epistemology means the critical study of the basic aspects, validity and limits of scientific knowledge. The term, coined in 1854 by the Scottish philosopher James F. Ferrier, over the years has come to assume a variety of meanings. It has also become synonymous with “philosophical perspective” as there is more than one type of epistemology, depending on the conception that scholars actually have of reality and of the role played by concepts and terms. To start with, we can state that many of the aspects argued regarding classifications, tacit knowledge and the functions of thought, of language and of the actions of everyday life (see Chap. 2) are also applicable to science. “But then how”, you might ask, “can a scientist be classified as just any other person?” Well, they cannot actually. A scientist is a different person in the same way that a plumber is different from a carpenter or a surveyor is different from an accountant. With a little patience and reading through to the end of this chapter, this statement will not seem so far- fetched. 3.1 Neo-positivism Comparing a scientist to a carpenter would no doubt be considered quite an insult for many scientists and philosophers (while carpenters would undoubtedly be glad to hear of the comparison). Such a reaction of astonishment or disbelief has very deep roots. We don’t know exactly how deep as the concept of science is, on balance, fairly recent (see Box 5.2). In fact, Galilei would never have considered himself to be a “scientist” (a term invented by William Whewell in 1833). Instead, the concept of reality had a huge influence on a certain type of epistemology, namely positivism, that developed during the second half of the nineteenth century. The roots of nineteenth-century positivism then led to the birth of neo-positivism. Neo-positivism (1900–1951) was a manifold cultural movement that influenced reflection on science for over half a century, until the start of the 1950s.1 Ludwig Wittgenstein (author of the Tractatus logico-philosophicus of 1921), the philosopher, logician, mathematician Bertrand Russell and the members of the so-called Vienna Circle are considered to be leading exponents of neo-positivism. Obviously, during this period other philosophical perspectives proposed by the mathematician, science historian and philosopher Federigo Enriques (1906) in Italy; by the philosopher, science historian, physicist and mathematician Pierre Duhem (1906); by the science philosopher Gaston Bachelard (1934) in France; and by the microbiologist and philosopher Ludwig Fleck (1935) in Poland were also at odds with each other. Despite this, neo-positivism was the dominant perspective at that time. Its heyday was around 1930 with the Vienna Circle, a group of scholars that, among others, included the German physicist and philosopher Moritz Schlick, who is considered the founder and main creator of the movement, the German philosopher and logician Rudolf Carnap, the mathematicians, logicians and philosophers Gottlob Frege (German), Kurt Gödel (Austrian) and Alfred Tarski (Polish) and the Marxist sociologist, economist and philosopher Otto Neurath (Austrian).2 The development of the movement (highly organised both from an editorial perspective with journals, series and encyclopaedias and from a communication point of view with conferences, international symposia and congresses) ground to a halt with the advancing of Nazism; in fact, many of the leading exponents (as Jews threatened by persecution) fled to the US. Neo-positivism is also known by the name of “logical empiricism” or “logical positivism”.3  Empiricism and logic are two fundamental terms that define the epistemological orientations of this movement. Empiricism is that Anglo-Saxon tradition which was taken forward by Francis Bacon (1561–1626), its forerunner, and by Thomas Hobbes (1588– 1679), John Locke (1632–1704) and David Hume (1711–1776). It considers the following: – Experience is the primary source of knowledge (knowledge can only come about from experience, that is from what occurs with immediacy. – The study of nature is the privilege of an empirical science. – Induction is the main form, or structure of thought, of scientific reasoning. – Perception and observation of phenomena are direct, without any previous theoretical influences. – The correct approach of the scientist is to tackle the topic of study without any preconceived ideas: they must ensure a tabula rasa of the theories available and in circulation and of the values and ideologies so that their observation is not influenced or distorted by them. – The critique and rejection of metaphysics must be clear as its statements (propositions) are not true and therefore make no sense (meaning). – The world is created from a set of single “elementary” facts. – The principle of causality is a metaphysical, or perhaps pre-scientific, principle that does not fall within scientific reasoning. In keeping with English empiricism, and in particular with Hume, it is argued that what we see and observe is only a succession of phenomena or events, not the creation of some by others. For logical empiricists, even the principle of determinism,4 which underpins the principle of causality, does not form part of science. This type of empiricism is called logic because it is based on a careful logical analysis of scientific claims through recourse to philosophy. Even if, according to this school of thought, philosophy is not a science (but only a minor discipline that cannot contribute knowledge), in any case it plays an important role: that of inviting a reflection on the language of science, that is on its syntax or logical rules that guide the construction of scientific findings. If instead philosophers intended to produce knowledge, they would alternatively deviate towards metaphysics. Instead, the role of philosophy is “only” to develop an activity with the aim of clarifying ideas, concepts and the method of science. In other words, philosophy is logical. The task of logic is to check the truthfulness or falsity of statements. This is what Schlick, the former Wittgenstein5 and then Carnap mean when they refer to logical analysis of scientific language. Carnap (1934, p. 279) in fact states: “Apart from the questions of the individual sciences, only the questions of the logical analysis of science, of its sentences, terms, concepts, theories, etc. are left as genuine scientific questions. We shall call this complex of questions the logic of science”. Finally, according to neo-positivists, it is necessary to achieve a greater unification of science that is still too fragmented into many disciplines that fail to communicate with each other and to create a singular method for science as a common base for all the disciplines. For this purpose, its proponents brought out a publication called Journal of Unified Science and two series of monographs that in 1938 converged to become the Library of Unified Science; the same year saw the publication of the International Encyclopedia of Unified Science. Succinctly summarised, there are five fundamental pillars of logical empiricism: the concepts of reductionism, meaning, verification, law and induction. 3.1.1 Reductionism According to the former Wittgenstein, everything is a fact, including words and statements. Therefore, if we are in the presence of truth, then consequently facts and words harmonise; this takes place because the statement expresses the reality, it is a reflection of it. In other words, there is an isomorphism between the structure of the fact and the structure of the statement. Consequently, we must consider as true statements (genuine) only those that allow us to establish a direct relationship between language (propositions) and the empirical reality (the facts). Only true statements have meaning and vice versa statements that have meaning are therefore true. The empirical reality, the world, consists of (and therefore is completely described as) a set of “elementary” or basic statements: the so-called “atomic propositions or protocol sentences” (Carnap, 1932/33). These are observational, concrete and direct statements (sentences), such as “patient no.18, 6 o’clock, temperature 37.5 °C” or “my body sees red”, which can be translated into the statement: “body C is now seeing red”. These statements do not require confirmation as they refer to the data of the senses and do not refer to other statements. Protocol sentences are useful as a basis for all statements of science that are often more complex, in the sense that they are constructed (like pieces of Lego) using various elementary statements. However, states Wittgenstein, there is a problem: in scientific tests there are many more statements than the elementary ones. This therefore means that we are presented with a certain number of statements that are somewhat redundant, perhaps even completely false. The former Wittgenstein is determined to remove every non-empirical statement. But, how can this be achieved? Schlick and then Carnap argue that to establish whether a statement is true (that it therefore has meaning) we need to deconstruct it in reverse, through subsequent definitions based on logical transformations and reduce it until only words appear in it whose meaning is no longer defined but solely demonstrated. As such, with the aid of logic, we would need to somehow scrupulously define things and show how complex statements are constructed starting from elementary ones. There is no way to understand the meaning of a statement (in other words to discover if it is true) if not progressively reducing it, through the correct application of logical rules, to ostensive definitions that guide us directly to the experience. This approach therefore guides us towards a reduction of all levels of reality to focus on just the one, the physical-natural aspect: there is nothing but a class of objects which are physical events. As a result we find ourselves faced not only with a logical reductionism but also with a methodological one, essentially reducing all the sciences into one singular discipline and so, essentially, any type or level of scientific language can be translated into the language of physics (physicalism).6 3.1.2 A Denotative Theory of Meaning In the example of the destruction of the Twin Towers (see Box 2.1) we saw how naming that event a terrorist attack or an act of war could actually make a huge difference. In the perspective presented in Chap. 2, names have a connotative meaning, in the sense that they connote (create) certain properties or characteristics.7 Instead, the neo-positivists, Frege in particular, and many modern-day scientists argue that names have a denotive meaning; in other words they appoint a referent (object) that already in itself exists. Names do nothing else but reflect reality, recording it. So, if the statements are true, they denote the truth; if they are false, they denote falsehood. Russel also, while making several changes and placing various limitations on Frege’s theory, would continue to pursue a theory denotative of meaning. The former Wittgenstein also supported this position. 3.1.3 The Verification Principle The third cornerstone of neo-positivist epistemology sees in ostensiveness (demonstrating) the only possibility of verification. Reference is made to possibility and not to tout court verification, because the latter is reached at a subsequent time, once the reduction has occurred. In fact, an elementary statement only has meaning if the rules (logics) of its derivation from protocol statements are clear, in other words if the path to be taken to verify it is known. The principle of verifiability, as a control criterion of the meaning of scientific statements, is the starting point to weaken metaphysical theses and in general all false statements. Schlick therefore theorises the two neo-positivism pivots: (1) the reduction of propositions to statements that (2) permit the possibility of verification. As the basic units of the world are elementary experiences (Carnap, 1928) and that for all sciences there is a single and certain foundation, which is experience, verification has a clear road ahead. 3.1.4 The Concept of Scientific Law Now let us take a look at the penultimate cornerstone of neo-positivism: the concept of scientific law. According to Carl Gustav Hempel, German mathematician, logician and philosopher, the task of scientific research is to discover regularity in the seemingly disordered flow of events and therefore to enucleate a set of general laws for the purpose of prediction and explanation, to make sense of it all. According to Hempel (1952/58), explaining and predicting are two activities that share the same structural logic. The scheme of scientific argumentation is, in fact, called hypothetical- deductive or nomological, in order words the search for nomos (which in Greek means “laws”). Hempel therefore corrects the inductivist position of neo-positivism of the 1930s, against which even Popper would conduct a full-scale battle. The model of hypothetical-deductive reasoning consists of a set of statements on individual events (particular) and a set of laws (general) that explain these individual events. A scientific law is a universal statement that affirms a constant relationship, simple or statistical, between properties. For example, the statements “all metals are conductors of electricity” and “the probability of a newborn being male is 50%” are statements of laws. However, the universality is a necessary but insufficient requirement (a condition). Other conditions are also required to be able to affirm that it in fact relates to a law. Second, it is essential that every single part of a statement is verifiable and has successfully passed verification tests or that it is deducible from other laws or theories that have been successfully verified. There is, however, one problem: neo-positivists realise that much scientific progress has also come about through laws without observable or ostensible referents, laws relating to hypothetical or theoretical entities (in other words, objects, events, attributes, which cannot be perceived by the senses or be directly observed, such as quanti or qualia). To resolve this problem, Hempel distinguishes empirical generalisations (wood floats in water, metal sinks) from actual theories (laws in the strictest sense). Even if both are verifiable, empirical generalisations are the result of an ascertainment; theories, instead, are the product of a law because the latter indicates a necessary relationship between events or properties of which the regularity relationship is stated. Therefore, empirical generalisations only characterise the initial stages of a science; then when it develops, it produces laws that are used to understand hypothetical entities: magnetic fields, energy, space, weight, force, mass, speed and so on. Consequently, the vocabulary of a science is split into two classes: observational and theoretical terms. Finally empirical generalisations are different from theoretical laws because the former have a limited field of validity (where reference is made solely to water, wood and metal); furthermore, within this field, there are always a number of exceptions: for example, empty metal spheres float while metals found in another shape, with a greater specific weight, in general tend to sink (ibid., p. 54). Formalising it with the language of logic, empirical generalisations can be represented in the following way: ∃x (Px→Qx), where ∃ means “for some”, while for the laws ∀x(Px→Qx) where ∀ means “for all”. 3.1.5 Induction Regarding this concept, the positions of neo-positivists are the most uncertain. Initially they considered that induction was the guiding structure of scientific reasoning. But later Carnap (on this point agreeing with Popper) changed this position, assigning to deduction the role of protagonist and to induction a secondary role. He also agrees that scientific discoveries do not take place through induction. However, Carnap considers (and this is the reason that grounds him in neo-positivist ideology) that how theories are formed is an irrelevant problem. What instead is important is how they can be justified, how they can be validated; in this case induction, with its logical rules, plays a fundamental role. Expressed otherwise, for Carnap the logic of induction is the expression of rationality; the scientist must accept the most probable hypotheses (instead Popper, as we shall see shortly, argues the opposite: it is the most improbable hypothesis that must be pursued). The logic of induction therefore maintains a direct relationship between experience and theory. Hans Reichenbach, German philosopher of science, also makes a valid contribution on this point, arguing that there is a clear distinction between the context of the discovery (the psychological, social, political and economic reasons that come into play in each scientific discovery) and the context of the justification, in other words the inductive procedures used to give basis and validity to the same discovery. According to Reichenbach (1951), the two contexts vary in that they are governed by different logics; in the context of the discovery, dissimilar logics are active (and permitted); in that of justification, the only logic that has credence is of the inductive type. 3.1.6 The Legacy of Neo-positivism The positions of logical empiricism may be considered by some to be splitting hairs, also in light of the highly philosophical, excessively formalised and even somewhat convoluted language with which they are discussed. They are positions that appear philosophically almost entirely outdated. And yet most modern-day scientists continue to be (practically) inspired by neo-positivism. Just think of how much the word “verify”8 is still widely used among scientists or the emphatic tone with which the words “facts” and “data” are uttered. Or how diffuse and dominant the reductionist logic in natural sciences is, which assimilates living material to the inanimate type, biology to physics and to mechanics, one animal species to another, ignoring the specificity of each species and the actual complexity of natural phenomenon. This reductionist culture guides, for example, research on genetically modified organisms (OGM) or animal experimentation; rodents, dogs, cats and monkeys are considered biological models for the human organism, ignoring the numerous differences that (in metabolism, in genetics, in physiology, in immunology, etc.) are found between one species and another. The critique levelled against such studies is not so much based on the call to simplify the phenomena; in fact, reducing complexity is a cognitive, as well as a practical, need that is linked to the limits of our reasoning ability. The critique instead focuses on the validity of the use of the animal model. In other words, it is as though the sociologist, to study hierarchies or the relations of power in organisations, should take the hive as a model. 3.1.6.1 We Are Not a Mouse Weighing 80 kg! A recent case concerns vitamin E: for many decades it has been widely promoted and sold as an adjuvant for fertility, for the nervous and muscular system. Today it is agreed that it is only essential for mice and not for human beings; in fact, if the food of mice lacks this vitamin, they experience severe deficiencies whereas if it is absent in the food of humans, no visible damage is evident. The French molecular toxicologist, Claude Reiss (2004), who for years studied the evolution of AIDS, documented the unreliability of experiments on animals: take, for example, the chimpanzee, the closest species to humans of those normally used in the laboratory. The chimpanzee is completely immune to AIDS: the virus has no effect on it. Instead, for example, with the Ebola virus, their physique behaves like ours. How, therefore, can a test on another species be validated when their reactions vary each time from ours? According to Reiss, the reductionist culture that guides the experimentation of products on animals (an indication of which is given by the term “clinically tested” stated on the pack) involves the occurrence each year in France of the hospitalisation of around 1,300,000 persons suffering from the detrimental effects of medicinal drugs. Similarly, in the US, 100,000 people die each year because of adverse reactions from such drugs, considered completely harmless in tests on animals. Drug reaction illness, from an epidemiological and statistical perspective, is (depending on the years) the fourth or fifth most frequent cause of death. In 1998 JAMA, one of the most important medical journals in the world, published two pieces of research that documented how 52% of drugs marketed in the US had caused serious adverse reactions, essentially leading to death, the risk of death or permanent disability. For this reason, it is important to extensively study neo-positivism and its scientistic ideology. However, neo-positivists have also asked relevant and undoubtedly very thought-provoking questions: which are the criteria to distinguish scientific knowledge from other types of knowledge (metaphysics, religion, ethics, aesthetics, etc.)? How is science progressing? How are scientific theories developed? How can we control the values and ideologies of scientists (as they are human beings) so that they do not contaminate scientific knowledge? How can we defuse arbitrariness and subjectivity? How can we construct a neutral and objective science? Through which method? What are the elements that characterise scientific reasoning (as distinct from other reasonings)? What are the tasks of science in modern-day times? What are the tasks of philosophy? Does science have a place in political, moral and social issues or should it avoid them? These are just some of the issues that logical empiricism addresses and places at the centre of contemporary reflection and debate. After all, if we started this book by focusing analytically on the difference between concepts and terms, this is also a stance attributable to the neo-positivists. However, at the same time other authors, while starting from the same questions, will provide different if not opposite answers. One of these is Popper. 3.2 Popper’s Realism and Critical Rationalism The intellectual training of Popper developed in a cultural climate dominated in fact by neo-positivism. He then began to study logic and methodology (even if he essentially remains a philosopher) and taught at the London School of Economics from 1946 to 1969, the year in which he retired, with a spell of nine years that he spent in New Zealand. While not being of English origin, due to his intellectual merits, he was appointed a baronet by the Queen. His reflection was in fact prompted by the questions posed by Viennese logical empiricism. Contrary to what was considered for a long time, Popper had never been a positivist and even less so a member of the Vienna Club. Conversely, his philosophy was in open controversy with logical empiricism and indeed he himself states, in Replies to My Critics and in Autobiography, that he was the artificier of his own undoing. Similar to the logical empiricists, Popper poses the problem of how to strictly outline the guidelines of scientific reasoning, which he (like them) considers rational: in fact, both for the neo-positivists and for Popper, science is first and foremost rationality. However, to this problem the author provides a response that is diametrically opposed to that presented by logical empiricists. 3.2.1 Falsifiability According to Popper, the role of experience has been overestimated. In fact, the task of experience is neither to give meaning to propositions (or statements) nor to verify them. The author, in his critique of neo-positivism, argues that the principle of verifiability, if applied literally, results in us denying the possibility that scientific laws are verifiable. In fact, what the scientists do when they verify is to focus on single events, in other words, on particular facts. However, the laws are universal statements. As such, how can a particular event verify a general statement? There is, therefore, a clear contradiction: no single statement of experience can guarantee the truth of a universal statement. Popper’s example (1934, p. 4) is well known: “no matter how many instances of white swans we may have observed [experience], this does not justify the conclusion that all swans are white”. To be able to say “all”, the scientist would have had to have actually seen them all, that is, to have experienced each of them. But this is impossible from a practical point of view. So do we need to dismiss the hope of finding universal laws and instead be satisfied with constructing statements that are valid but only locally? Some post-Popper scholars would answer yes to this question (see Chap. 4). Instead, Popper does not deny this possibility but shrewdly turns the verificationist approach around: while a very large number of cases drawn from practical experience are never able to demonstrate the validity of a universal assertion, in any case even just the one case is sufficient to highlight its falsity. Let us look at an example. The universal law “all metals conduct electricity” cannot be verified. However, if we find even just one case in which this does not occur, the assertion loses its universality and it would therefore be necessary to review its scope. According to Popper, it is impossible to justify the validity of a universal theory by means of experience, even for purely practical reasons: we would need to find all the pieces of metal existing on this earth and check whether each of them conducts electricity; this would involve a huge number of resources, time, specialist personnel and so on, with the risk that perhaps some pieces of metal might be overlooked and therefore not be verified. Science does not proceed by experience and verifications, as the neo-positivists state (and how most contemporary scientists still think), but by hypotheses and falsifications or rather by Conjectures and Refutations, also the title of his most important work, the one that made him famous (Popper, 1963). However, in Popper the experience is not completely devalued, but takes on a different role from that afforded to it by the logical empiricists. Subsequently Carnap would turn his back on the notion (illusory and impractical) of verifiability, instead replacing it with that of “degree of confirmation”: a scientific hypothesis can never be verified, but only confirmed (supported, sustained) by empirical evidence. Popper therefore persuades his colleagues that experience has the task of falsifying a theory, in other words of finding that particular case in which what was envisaged by the statement is not evident to our senses. So does this mean that the scientist must adapt to working in a world without certainties? Not exactly. Of course, there will be certainties. So, if we can never conclusively know if our theory is true, we can instead know, with a certain degree of confidence, if our theory is false. 3.2.2 Science on … Stilts The scope of Popper’s statements does not end with the important but finite critique of the concept of verifiability but has implications of a more general scope. The first of these implications has to do with the building blocks of scientific knowledge. Popper introduces the notion, unknown to neo- positivists, of the fallibility of science: scientists can in fact make mistakes and fail to see the truth; they can never be assured that their theory is true. Hence, Popper is a proponent of the idea that the theories are plausible, that is, merely an approximation to the truth and not a reflection of it. This does not necessarily imply a sceptical or relativistic conception of science, but only the idea that science does not rest on absolute and constantly stable foundations, but instead on a somewhat slender base; so thin in fact that even one case could bring into question a theory that has been accepted for decades or even centuries. Science is therefore a stilt house, a construction of fragile materials which rests on stilts, not a castle forged on rock. 3.2.3 Political Liberalism The second implication of Popper’s philosophy is a liberal conception, both of science and of society. In fact, his philosophy goes beyond the limited scope of science and also has reflections in political thought. The author argues that if from a theoretical point of view assertions and theories can be continually questioned, the practical condition that guarantees this possibility is that there is a science (and consequently also a society) that is free-minded, open to critique, not set in its ways or in stone, and, as such, therefore willing to continually question itself. According to Popper, this type of science is only possible in a democratic and liberal society, but undoubtedly has no place in a totalitarian society (Nazi, fascist, communist, theocratic, etc.). 3.2.4 The Critique of Induction By replacing the criterion of verifiability with that of falsifiability, Popper deals another fell swoop to neo-positivism as it removes the falsifiability of an aspect that is particularly dear to logical empiricists: that of being able to attribute significance (meaning) to statements, that is, to discover and separate true statements from false ones, such as tautologies, syllogisms and pseudo-scientific propositions. In fact, according to neo-positivists, verification paved the way for the discovery of false statements (therefore without meaning) even if they seem true from a logical perspective. In other words, verification compensated for the flaws of logic and became a resource to draw on when the latter was in difficulty. Let’s look at the examples (see Table 3.1). Table 3.1 A syllogism A B C Major premise (or rule) Minor premise (or case) Conclusion (or result) All metals are conductors of electricity Copper is a conductor of electricity Copper is a metal Nobody would have anything to object to these three statements. Now let’s look at these three examples (Table 3.2). Table 3.2 Other syllogism A B C Major premise (or rule) Minor premise (or case) Conclusion (or result) All metals are conductors of Water is a conductor of Water is a metal electricity electricity Adults smoke I smoke I am an adult The human being eats salad The goat eats salad The goat is a human being Even if logically flawless, we perceive that there is something amiss in these conclusions even if we cannot explain why. Logical empiricists used to say that this was the time to introduce verification. Through the inductive method and experience, it would reveal nonsense and therefore the falsity of statements that from a logical-formal point of view seemed true because they followed a certain rigorous path (apparently). The problem stems, therefore, from the fact that logic only deals with the form (the structure) of an expression and not with its content. Popper criticises this representation of the problem of induction and of the meaning. He retains that induction is a logically unjustifiable process, psychologically impossible and epistemologically irrelevant. Indeed, scientific discovery does not proceed by induction; rather it advances by: – Deductions, that is moving from one idea to another (contrary to the conception of the scientific mind as a tabula rasa) and not from one experience to another; – Falsifications, in the sense that the only valid conclusions are those that come about from disproof or falsifications of theories, not from their verification for which Popper (1935, Chap. 11) leans towards the concepts of “corroboration” and “confirmation” of a theory; – Trial and error, therefore also randomly; – Following the most improbable hypotheses (and not the most probable ones as Carnap argued). The scientist differs from the layman because of their reluctance to follow the most commonly trodden path, the idea closest to hand, the most convenient solution. 3.2.5 The Demarcation Criterion The implications of the philosophy of Popper are therefore very productive and continue to evolve. Another of these involves the demarcation criterion. The author argues that falsifiability is not a criterion to establish meaning (or the truth of statements); in other words falsifiability does not replace verifiability and should not fulfil the same function. Popper considers that scientists should not worry whether the theories they are working with are true or false. This preoccupation that had kept logical empiricists awake for many a night is a useless concern because scientists will never be able to be assured of the certainty of their theory. As, at any time or in any part of the earth, a contrary case could bring it tumbling down; the scientist is never sure that their theory (which seems to work) is true. The fact of being right for much of the time in the face of critiques and with all the possible counter-experiments does not necessarily mean they will stand the test of time forever. Our theories, states Popper, are always temporary. They are not true, but simply those that are most appropriate for our purposes and that persisted up until then. Therefore, falsifiability is only a demarcation criterion, of separation between the statements of science and those of pseudo-sciences or of metaphysics, not a criterion to ascertain the truth of scientific statements. What then is the difference between science and pseudo-sciences? According to Popper, a statement is scientific when it is presented, from the point of its formal structure, in such a way that it can be falsified, that is disproved, criticised and debated. For this reason, again according to Popper, psychoanalysis, Marxism (historical materialism), astrology and palmistry, as well as sociology, psychology and history, are pseudo-sciences because they do not present their statements in a way that they can be refuted. How can the Oedipus complex be falsified? Did Freud express it in such a way that it could be disproved? This doesn’t mean that propositions (assertions and statements) of pseudo-sciences make no sense, that is without meaning, as the logical empiricists strenuously argued—simply that their statements are not scientific. They belong, let’s say, to the private realm of individual preference. From a psychological perspective, they can be an important source of inspiration but must not be confused with actual science. 3.2.6 Rationality as Critique and Discussion One of the last implications of Popper’s theory concerns the role of rationality. According to the author, presenting our ideas in such a way that they can be refuted means being receptive to critique and agreeing to follow a transparent and rational way of proceeding. He in fact affirms that “critique is the best synonym of rational” and rationality is the foundation of scientific activity. He apparently also appears to be open mind in terms of pseudo-sciences and does not put down non-scientific statements. Instead, Popper (1934) says that it is, at times, also possible to learn something very interesting from a pseudo-scientific or metaphysical theory. Only that science has a rational basis while the other stances do not. Exercises Exercise 1 In geometric optics rays of light propagate in a straight line. This is presented as a general law. Now, instead, discover which particular conditions are necessary for this to happen. Also describe (consulting a text on optics or physics) the situations in which this law is not applicable. Exercise 2 Consider the following syllogisms. All forks have four teeth My grandfather has four teeth My grandfather is a fork All rivers have a bed I have a bed I am a river Grass is mortal Men are mortal Men are grass What’s the problem here? Where’s the error? What is a “grass syllogism” and who invented this expression? Why is it important to recognise the correct value of logical connectives and quantifiers? Exercise 3 According to Popper, applying the demarcation criterion, astrology and alchemy are not sciences. However, Keplero made astrological predictions and Galilei produced horoscopes on commission, convinced that the stars could determine the choices of individuals. Furthermore, Tycho Brahe, Boyle  and Newton were also alchemists. So much so that Newton’s interest in alchemy cannot be separated from his contributions to science: if he had not believed in the occult idea of action at a distance, through the void, he probably would not have developed his theory of gravity. Moreover, he spent September of each year immersed in alchemy-related experiments, whose preferred metal is mercury. His nervous exhaustions and eccentricity were then attributed to psychic and neurological symptoms of poisoning induced by mercury. In support of this, after his death, his body was exhumed and a high concentration of mercury was in fact found in his hair, probably because of the numerous alchemy experiments he had conducted. Can we now then say that these scholars were not scientists? What does this way of reasoning remind you of? Further Reading Musgarve (1993) Nagel (1961) Popper (1956–57) Check Your Preparation 1. What are “elementary statements”? 2. What are empirical generalisations and how do they differ from theories? 3. What legacy has neo-positivism left us with and why is it important to study it? 4. What is the difference between verifiability and falsifiability? 5. What is the purpose of the demarcation criterion? References Bachelard, G. (1934). Le nouvel esprit scientifique. PUF (transl. The New Scientific Spirit. Beacon Press, 1985). Carnap, R. (1928). Der logische Aufbau der Welt. Weltkreis. (transl. The Logical Structure of the World. University of California Press, 1967). Carnap, R. (1932-33). Über Protokollsätze. Erkenntnis, 3, 215–228. (transl. On Protocol Sentences. Noûs 1987, 21(4), 457–470. https://doi.org/10.2307/2215667). Carnap, R. (1934). Logische Syntax der Sprache. Springer (transl. The Logical Syntax of Language. Routledge & Kegan Paul, 1967.) Duhem, P. M. M. (1906). La théorie physique: son objet et sa structure. Chevalier et Rivière. (transl. The Aim and Structure of Physical Theory. Princeton University Press. 2nd. ed., 1991). Enriques, F. (1906). Problemi della scienza. Zanichelli. (transl. Problems of Science. The Open Court Pub. Co. 1914). Fleck, L. (1935). Entstehung und Entwicklung einer wissenschaftlichen Tat- sache. Einführung in die Lehre vom Denkstil und Denkkollektiv. Benno Schwabe. (transl. Genesis and Development of a Scientific Fact. Chicago University Press,1979.) Hempel, C. G. (1952). Fundamentals of Concepts Formation in Empirical Science. University of Chicago Press. Musgarve, A. (1993). Common Sense, Science and Scepticism: A Historical Introduction to the Theory of Knowledge. Cambridge University Press. Nagel, E. (1961). The Structure of Science: Problems in the Logic of Scientific Explanation. Harcourt, Brace & World. [Crossref] Popper, K. (1934). Logik der Forschung. Springer. (transl. The Logic of Scientific Discovery. Basic Books, 1959). Popper, K. (1956–57). Realismus und das Ziel der Wissenschaft. (transl. Realism and the Aim of Science. Hutchinson,1983.) Popper, K. (1963). Conjectures and Refutations. Routledge and Kegan Paul. Reichenbach, H. (1951). The Rise of Scientific Philosophy. University of California Press. [Crossref] Reiss, C. (2004). Science Based Toxicology: A New Strategy for Toxic Risk Assessment in the 21st Century. Animal Aid. Footnotes 1 Forerunners of this movement, among others, are indicated (and not always entirely correctly) including the German physicist Ernst Mach (1838–1916), the Austrian physicist, mathematician and philosopher Ludwig Eduard Boltzmann (1844–1906), the German philosopher and psychologist Hermann Brentano (1838–1917) and the Austrian philosopher Alexius Meinong (1853–1920). 2 Despite sharing the same intellectual perspective, the authors are also very different from each other, whose positions are not always compatible or whose positions are not always compatible or superimposable. 3 Even if the term positivism is rejected by Carnap. 4 Principle that stems from a philosophical conception with a marked mechanistic character, according to which each phenomenon or event of the present is necessarily determined by a historic phenomenon or event. 5 We say former Wittgenstein because thereafter he radically distanced himself from the initial positions expressed in Tractatus. 6 In social sciences, this position has led to the rejection of mentalism and an embracing of behaviourism. Behaviourism rejects the use (for example) of concepts of intelligence, intention, interpretation and so on, to explain human behaviours because concepts (being in the mind) cannot be observed. Behaviourism only focuses on actions, only on observable entities. If in the context of biology all the phenomena of life can be described and explained through physical and chemical laws, in the sphere of psychology, behaviourism theories consider that all the psychic and mental processes must necessarily be reduced to behaviours and must therefore be expressed in neurophysiological terms. 7 If we are consistent with a constructivist approach, we should use the term “attributes” instead of “properties” or “characteristics”. In fact, the properties are elements possessed by the referent (therefore an objectualist position), while the attributes are elements attributed to the referent by an observer. Added to this is the fact that different observers could attribute different elements to the same referent. 8 Paradoxically, this term, with its Latin roots, made up of verum (true) and facere (make, render) seems more akin to a constructivist epistemology.