Good Science - Philosophy of Science - Lecture Notes, Study notes of Philosophy

Download Good Science - Philosophy of Science - Lecture Notes and more Study notes Philosophy in PDF only on Docsity! Explanation Many believe that good science does not merely describe and predict phenomena, but that it must also explain them. Realists argue that the truth (or approximate truth) of a statement is a necessary condition for it to be part of a genuine scientific explanation. Thus, realists claim that there are no genuine explanation possible under van Fraassen’s constructive empiricism. Explanations tell us why things are as they are. The window is broken because it was hit by a stone. (Causal, in terms of cause and effect) The pressure of the gas rose because the volume was fixed and the temperature was increased. (Nomic/nomological, in terms of laws of nature) They are not answering the phone because they want to get some work done. (Psychological, in terms of beliefs and desires) What kinds of explanation are legitimate? The scientific revolution was characterized by the rejection of teleological (i.e., goal/purpose-oriented) explanations, on the basis that they do not specify the material cause of things. The stone fell to Earth because its natural place is at the centre of the universe. Thus, it is widely thought that only causal explanation are scientifically legitimate. Functional explanations are often used in science, but it is usually assumed that these explanations are legitimate only as long as there are used as ‘short-cuts’ standing for causal explanations. The handle of the spoon is curved to fit comfortably in the hand. (Functional) Giraffes have long necks because it enables them to reach the leaves of tall trees for food; in other words it is an adaptation to the environment. (Evolutionary) Other kinds of explanations have been deemed unscientific on the basis that they are not based on a testable causal mechanism. Docsity.com His violence is the result of a repressed Oedipal complex. (Psychoanalytical) She is adaptable because she is a Pisces and that is a water sign. (Astrological) The rise of capitalism was an inevitable result of the instabilities in the organization of production in eighteenth century Europe. (Marxism) Some explanations refer to laws of nature rather than to a cause. The pressure of the gas rose because the volume was fixed and the temperature was increased. (Nomological) Some people hold that reference to a law needs to be supplemented with a causal account of why the law hold. The gas laws are to be explained in terms of the molecular motions that cause the phenomena of pressure and temperature. The trouble with causal explanation However, since Hume did his analysis of causation, it is not at all clear that the notion of causation is scientifically respectable. Thus, those (like the logical positivists) who agree with Hume that what we call causation is just regularities in the phenomena think that causal explanation is reducible to nomic explanation. The idea is to combine Hume’s regularity theory of causation with a regularity theory of laws so to dispense with metaphysical ideas of causal or necessary connection between events. The covering law model of explanation One of the most influential theories of scientific explanation is Hempel’s covering law model. To give an explanation of some phenomenon is to show how it follows from a law (or set of laws) and initial conditions. Laws of celestial mechanics + Relevant positions, masses and velocities of the Sun, Earth, and Moon ├ Darkening of the sky during a solar eclipse. Docsity.com 4. Symmetry: Many scientific laws describe correlations (or inverse correlations) between two or more variables. (E.g., Boyle’s law). The problem for the DN model is that then the variables explain each other, i.e., there is a symmetry of explanation where there should not be one. Compare: A gas is sealed in a container of fixed volume and heated strongly. If the volume of a gas is kept constant then its temperature is directly proportional to its pressure. Therefore, the pressure of the gas rose. With: A gas is sealed in a container of fixed volume and its pressure rises. If the volume of a gas is kept constant then its temperature is directly proportional to its pressure. Therefore, the temperature of the gas rose. 5. Prediction and explanation Hempel advocates the thesis of “structural intergrity”, according to which explanations and predictions have the same structure. The only difference between an explanation and a prediction is that in the case of an explanation, we already know that the conclusion is true, while in the case of a prediction we do not. E.g., Newton’s prediction of Halley’s comet in 1758. However, there are many cases where being able to predict a phenomenon does not translate into being able to explain it. E.g., the fall of the needle of a barometer allows us to predict that there will be a storm but does not explain it. Also, there seem to be good explanations that cannot be used to make prediction. E.g., theory of evolution The Inductive-Statistical model The DN model is unable to deal with statistical or probabilistic laws, even though they are often used in science. Hempel suggested another model of explanation to deal with these cases. The Inductive-Statistical (IS) model assumed that in cases of probabilistic explanation, the law plus auxiliary conditions makes the explanandum very likely. The Docsity.com IS model is a kind of covering law model, as an explanation is still to show that a phenomena is an instance of a law. However, IS explanations are not deductions (as in the DN model), but rather inductions, since the truth of the conclusion is not guaranteed by the truth of the premises. Problems with the IS model Cannot deal with low probabilities E.g., syphilis and paresis Cannot deal with cases where there is a high probability correlation between two events, but where neither explain the other. E.g., the fall of a barometer needle and the occurrence of rain. Laws of nature vs. mere universal generalizations Defenders of the covering law model must also say precisely what is a law of nature without referring to anything metaphysical. They say that a law of nature is a universal generalization which is true of our world, but not all such generalizations are taken to be laws of nature. Compare: All solid spheres of gold have a diameter of less than 100 miles. All solid spheres of enriched plutonium have a diameter of less than 100 miles. Other theories of explanation Causal account of explanation: E.g., W. Salmon and D. Ruben. Seems to avoid all the problems of the covering law model. Problems: Requires an account of causation There are cases where one law is used to explain another with no mention of causation. Pragmatic account of causation: ►E.g., van Fraassen What counts as an explanation depends on one’s interests. Goes against realism. Docsity.com E.g., Why did the car crashed? Policeman: the driver was driving too fast Meteorologist: it was raining and the street was wet Civil engineer: the turn is too sharp at this place Mechanics: the tires were too old and worn Inference to the best explanation Inference to the best explanation (IBE) is a rule of inference stating that, when we have many competing hypotheses, all of which are empirically adequate to the phenomena in some domain, we should infer the truth of the hypothesis that gives us the best explanation of those phenomena. Term introduced by Gilbert Harman, in 1965. Also called ‘abduction’, from the terminology of Charles Peirce (1839-1914). Your friend is on crutches and has a cast on her right leg. Possible explanations: 1- You friend is making a fashion statement. 2- You friend is in a play, and that’s part of her costume. 3- You friend lost a stupid bet. 4- You friend broke her leg. The argument has this form: If p, then q q Therefore p. If your friend has a broken leg, she is on crutches and has a cast. Your friend is on crutches and has a cast. Therefore, she has a broken leg. However, this is an invalid form of argument. E.g.,: If something is a tree, it needs water. Docsity.com following features of science are in need of explanation, and that realism offers the best explanation: 1) Induction based on scientific theories is reliable. 2) The degree of confirmation of a theory is heavily theory-dependent, i.e., depends on our background theories. 3) Scientific methods are instrumentally reliable, i.e., they work in practice. Another characteristic of the scientific practice that is in need of explanation, according to the realists, is: 4) The persistent and often successful search for unified theories of diverse phenomena. If two theories, T and T’, from different domains of sciences, are both empirically adequate, it does not mean that their conjunction T & T’ is also empirically adequate. But if T and T’ are true, then their conjunction T & T’ will also be true (and so be empirically adequate as well). So only realists are motivated to believe that unifying theories is a good idea. Van Fraassen replies to #4 is that scientists do not simply conjoin theories in this way. To produce a unified theory is more a matter of correction than of conjunction. If T and T’ are merely approximately true, then T & T’ will not necessarily be approximately true. E.g., T and T’ could be inconsistent. There are pragmatic grounds for investigating the conjunction of accepted theories in the search for empirical adequacy. Van Fraassen’s reply to 1-4: For any feature of science that produce instrumental success, the antirealist can find inductive ground in the history of science for believing in its pragmatic value. Docsity.com Scientific theories have predictive success because they are subject to selection based on competition. “The success of current theories is no miracle. It is not even surprising to the scientific (Darwinist) mind. For any scientific theory is born into a life of fierce competition, a jungle red in tooth and claw. Only the successful theories survive – the ones which in fact latched on to actual regularities in nature.” (van Fraassen, 1980) The realist reply is that while van Fraassen explains how empirically adequate theories have become dominant, it does not explain why these theories are empirically adequate n the first place. However, to adopt the realist view that the empirically adequate theories are approximately true does give such an explanation. Van Fraassen’s criticism of IBE Assuming IBE is an acceptable strategy, it allows us to pick the best explanation for a phenomenon among all the potential explanations we have. IBE says that we have reason to think that this best explanation is in fact true (or approximately true). However, how do we know that the true explanation of the phenomenon in question was among the options we are choosing from? This is exploited by van Fraassen in his criticism of IBE. Two related arguments: 1. The argument from indifference 2. The argument from the best of a bad lot The argument from indifference There are many theories that are empirically equivalent, but ontologically incompatible. That is, many theories say the same thing about the observable world, but differ in what they say about the unobservable. So it is very unlikely that the one true theory will be among those we thought of. Therefore, by using IBE, we will find the best theory among those we have, but that does not give us any reason to think that this theory is in fact true. In other words: even if you Docsity.com can trust IBE to find the best theory among those you have, maybe in fact you do not have the true theory in the alternatives you apply IBE to. IBE works the same regardless of whether or not the true theory is among those to choose from; in short, IBE is indifferent to truth. This is against: best theory = true theory The argument from the best of a bad lot Given that there is an infinity of empirically equivalent theories, how do we know that the best theory is among those we are evaluating? Even if the best theory is necessarily true, if all the theories we are looking at are false, IBE will only give us the best of a bad lot. To assume that we do have the best explanation among those we are evaluating requires a ‘principle of privilege’. In other words: even if you in fact have the true theory among the alternatives you apply IBE to, because IBE does not guarantee that the ultimate best explanation is among the alternatives, you cannot trust IBE as a rule of inference. For all we know, we only have the best of a bad lot. This is against: best we have = ‘the’ best Selective Scepticism? We saw that realists claim that van Fraassen is guilty of selective scepticism in regard the underdetermination problem. On one hand, van Fraassen refuses to use non-empirical evidence (e.g., IBE) to break the underdetermination among strongly empirically equivalent theories, that is, to decide which theory is true among theories that are identical in fitting all the past and future empirical facts. Yet, on the other hand, he believes that we can know which theory is empirically adequate (i.e., fit all the possible empirical facts) among the alternatives given the available facts, that is, to break the underdetermination among weakly empirically equivalent theories (i.e., identical in fitting all the empirical facts so far). So realists argue that van Fraassen either: Docsity.com