Journal of the Asiatic Society of Bangladesh (Hum.), Vol. 60(1), 2015, pp. 91-107 RATIONAL RECONSTRUCTION IN THE NATURE OF SCIENTIFIC TRUTH Md. Abdul Mannan* Abstract Conventional wisdom suggests that scientific knowledge is objective and a proven truth. This paper challenges the conventional wisdom and argues that scientific knowledge offers only partial or relative truth. If we analyze some scientific phenomena such as theory-change and the unobservable entities assumed in science, we will find a different picture about the nature of scientific truth. Philosophers of science view these phenomena and seek to rationalize what is achieved by scientific discoveries: truth or something else. Looking at some such views we finally find that achievement of scientific enterprise is not absolute truth, but it is human truth - the truth which is relative to human conditions, be it intellectual or psychological. Introduction What kind of truth science obtains by its theoretical investigations? The question becomes more significant when we find that scientific theories assume some entities which are not observable -- neither in experience nor in instrument. Scientific entities such as aether, electron, gene, field and many other entities assumed by different theories are not observable. In describing these entities, are our theories true --- where there is no scope to compare between the assumed entities and the reality as such? Answer to this kind of questions depends on what we think about the nature of scientific enterprise. Our theories may or may not be true, but first of all, there must be the world external to our thinking. This view is called metaphysical realism which holds that there are truths about the actual structure of the real world that do not depend on cognitive capacities of human investigators. According to this view, there is exactly one true and complete description of the way the world is. So, metaphysical realism is not a thesis now known, it is a thesis about some possible theory. However, it is not sufficient for the truth to be there, but it is necessary for science to be able to get that truth. This view about the ability of science is called epistemological realism. According to this view, * Associate Professor, Department of Philosophy, University of Chittagong 92 Md. Abdul Mannan the real structure of the world is cognitively accessible to scientific investigations. It holds that certain forms of evidence or empirical supports are so epistemologically probative which any theory that exhibits them can legitimately be presumed to be true, or nearly so. Metaphysical realism and epistemological realism together claim that the world of our experience is real and we have the capacity to understand that reality. Secondly scientific realism asserts that the unobservable entities that the theoretical terms indicate do exist. By supposing their existence we can give good explanation of the behavior or characteristics of observable entities; otherwise the world remains completely inexplicable. Theoretical entities explaining the observable phenomena --- observable not merely by their existence, but by their being the way --- are assumed by theory. It is assumption, for we do not have any scope to compare between our theories and assumed entities. So, sometimes the face value of the theory decides about the truth of the unobservable. Alfred Tarski1 re-established a theory of absolute truth which shows that we are free to use the intuitive ideas of truth as correspondence with the facts. But what is ‘correspondence with the facts’? There are two formulations each of which states very simply under what conditions a certain assertion corresponds to the fact. One, the statement or the assertion, ‘Snow is white’ corresponds to the facts if and only if snow is indeed white. Two, The statement or the assertion, Grass is not red’ corresponds to the facts if and only if grass is indeed not red. For Tarski, a theory may be true even though nobody believes it, and even though we have no reason to accept it or for believing that it is true. According to correspondence theory, even if we hit upon the true theory, we shall as a rule be merely guessing, and it may well be impossible for us to know that it is true. On the other hand, a theory may be false although we have comparatively good reason for accepting it.2 William James3 suggests that truth is a property of certain of our ideas. It means their ‘agreement’, as falsity means their ‘disagreement’ with reality. 1 Alfred Tarski (1901–1983) was a Polish logician, mathematician and philosopher. He worked on the foundation of modern logic, formal notion of truth and analytic philosophy. His theory of truth is known as correspondence theory of truth. According to this view a statement is true if it corresponds to the reality. 2 Alfred Tarski, The Semantic Concept of Truth: and the Foundation of Semantics, In Philosophy and Phenomenological Research, Vol. 4, No. 3, (International Phenomenological Society, 1944), p. 343. 3 William James (1842–1910) was an American philosopher and psychologist. James was one of the leading thinkers of the late nineteenth century and is believed by many to be one of the most influential philosophers the United State has ever produced. He is considered to be one of the major figures associated with the philosophical school known as pragmatism. Rational Reconstruction 93 Pragmatists4 and intellectualists5 both accept this definition as a matter of course. They begin to quarrel only after the question is raised as to what may precisely be meant by the term ‘agreement’ and what by the term ‘reality’ which ideas to agree with. The popular notion is that a true idea must copy its reality. It is widely believed that our true ideas of sensible things do indeed copy them. James says, shut your eyes and think of yonder clock on the wall, and you get just as true picture or copy of its dial. But your ideas of its ‘works’ (unless you are a clock maker) is much less of a copy; yet it passes muster, because it in no way clashes with the reality. Even though it should shrink to the mere word ‘works’, that would still serves you truly; and when you speak of the ‘time-keeping function’ of the clock , or of its spring’s ‘elasticity’, it is hard to exactly what your ideas can copy.6 In this situation a pragmatist asks ‘what concrete difference will its being true make in any one’s actual life? How will the truth be realized? What experience will be different from those which would be obtained if belief were false? What is the truth’s cash-value in experimental terms? The answer would be: true ideas are those that we can assimilate, validate, corroborate and verify. False ideas are those that we cannot. So, the meaning of the truth is all that is known-as truth.7 Now the question is what kind of truth science achieves. Is it possible to achieve the absolute truth in the course of theory-change? There are different views in this regards, that is, one thing is viewed from different rational reconstruction. Every rational reconstruction seeks to explain the truth within the activities of science. In rational reconstruction one explains the various kinds of activities of science with one single general rationale, which at the same time explains the nature of truth. In this regards, Popper, Kuhn, Lakatos, Lauda and Toulmin8 are among 4 Pragmatism is a philosophical view that began in the United States around 1870. Pragmatism is a rejection of the idea that the function of thought is to describe or mirror the reality. According to this view, assertions that predicate truth of a statement attribute the property of useful-to-believe to such a statement. 5 Intellectualism, in other words realism, stands opposite to pragmatism. It holds that function of thinking is to seek for truth of the world. It also holds that truth is the correspondence to the reality. 6 William James, Essays in Pragmatism, (New York, 1966), pp. 159-160 7 Ibid, pp. 160-161 8 Karl R. Popper, Thomas S. Kuhn, Imre Lakato, Larry Laudan and Stephen Toulmin are the most influential figures in philosophy of science in contemporary period. They all have independent views about scientific change and the nature of scientific truth within change. 94 Md. Abdul Mannan the philosophers who did this work. In this course we find scientific truth in different nature: (1) Science inquires objective truth but achieves ‘truth-likeness’ (Popper) (2) Science is theory-based, so its achievement is relative truth ( Kuhn) (3) Science aims at discovering facts, but facts do not necessarily correspond to the reality (Lakatos) (4) Meaning of truth is problem-solving-effectiveness, empirical or conceptual problem (Laudan) (5) Essence of truth is intellectual satisfactoriness (Toulmin) Truth-likeness Scientific truth is viewed as truth-likeness in Popper’s9 philosophy of science. For him, science aims at truth in Tarski’s terms, that is, objective truth or correspondence truth10 (Correspondence theory of truth holds that a proposition can be true if and only if it corresponds to reality). He holds that scientific method is a method of falsification. In this method, science cannot verify the truth, but it eliminates the falsity from our ideas. So, reduction of falsity entails the nearness of truth – the more nearness the more truth-likeness. This is all that science does with regards to truth. In science, Popper argues that we seek for highly informative theory, while the highly informative theory has low probability to be true. From this point of view, we do obviously not obtain the truth or approach to the truth.11 Theory of falsification allows us to know that we carry on search for truth, though we may not know when to have found it.