Metaphysicians speak of laws of nature in terms of necessity and universality; scientists, in terms of symmetry and invariance. In this book van Fraassen argues that no metaphysical account of laws can succeed. He analyzes and rejects the arguments that there are laws of nature, or that we must believe there are, and argues that we should disregard the idea of law as an adequate clue to science. After exploring what this means for general epistemology, the author develops the empiricist (...) view of science as a construction of models to represent the phenomena. (shrink)

Reprint of the original, first published in 1869.

That no member of a natural kind can switch kinds is a consequence of David Wiggins’ view that the identity conditions for such things are given by the natural kind itself. If dog is a natural kind, then dogs must be dogs and one dog cannot ‘turn into’ something else, say, by gradually ‘becoming’ a mass of tissue (as Marjorie Price had held). Were such a transition to involve the persistence of the same thing, then the thing in question would (...) comply with conditions of identity not restricted to dogs. To provide for such transitions James Baillie suggests alternative conditions of identity, based on Andrew Brennan’s notion of ‘survival’ (itself borrowed from Parfit). Survival requires that the earlier thing be ‘structurally similar to’, and ‘play a significant and direct role in the production of’ the later thing (sufficiency is gained if, in addition, they are composed of the same kind of matter). Unlike identity, however, survival is what Wiggins calls a ‘branching’ relation, capable of linking a single thing with two or more equal ‘competitors’ (as apparently happens in cases of brain fission). To provide conditions of identity per se, Baillie follows Parfit, who claimed that our identity is preserved by psychological continuity when there is no branching. Members of natural kinds, such as dogs, are now said to be reidentifiable over time by the relation of non-branching survival. I argue against this on the ground that we can know when this relation obtains only when we are already able to individuate things by a different sort of relation, such as those associated with natural kinds. (shrink)

Science depends on judgments of the bearing of evidence on theory. Scientists must judge whether an observation or the result of an experiment supports, disconfirms, or is simply irrelevant to a given hypothesis. Similarly, scientists may judge that, given all the available evidence, a hypothesis ought to be accepted as correct or nearly so, rejected as false, or neither. Occasionally, these evidential judgments can be made on deductive grounds. If an experimental result strictly contradicts a hypothesis, then the truth of (...) the data deductively entails the falsity of the hypothesis. In the great majority of cases, however, the connection between evidence and hypothesis is non-demonstrative, or inductive. In particular, this is so whenever a general hypothesis is inferred to be correct on the basis of the available data, since the truth of the data will not deductively entail the truth of the hypothesis. It always remains possible that the hypothesis is false even though the data are correct. (shrink)

According to a causal model of explanation, we explain phenomena by giving their causes or, where the phenomena are themselves causal regularities, we explain them by giving a mechanism linking cause and effect. If we explain why smoking causes cancer, we do not give the cause of this causal connection, but we do give the causal mechanism that makes it. The claim that to explain is to give a cause is not only natural and plausible, but it also avoids many (...) of the objections to other accounts of explanation, such as the views that to explain is to give a reason to believe the phenomenon occurred, to somehow make the phenomenon familiar, or to give a Deductive-Nomological argument. Unlike the reason for belief account, a causal model makes a clear distinction between understanding why a phenomenon occurs and merely knowing that it does, and the model does so in a way that makes understanding unmysterious and objective. Understanding is not some sort of super-knowledge, but simply more knowledge: knowledge of the phenomenon and knowledge of its causal history. A causal model makes it clear how something can explain without itself being explained, and so avoids the regress of whys, since we can know a phenomenon's cause without knowing the cause of the cause. It also accounts for legitimate self-evidencing explanations, explanations where the phenomenon is an essential part of the evidence that the explanation is correct, so the explanation can not supply a non-circular reason for believing the phenomenon occurred. There is no barrier to knowing a cause through its effects and also knowing that it is their cause. The speed of recession of a star explains its observed red-shift, even though the shift is an essential part of the evidence for its speed of recession. The model also avoids the most serious objection to the familiarity view, which is that some phenomena are familiar yet not understood, since a phenomenon can be perfectly familiar, such as the blueness of the sky or the fact that the same side of the moon always faces the earth, even if we do not know its cause. Finally, a causal model avoids many of the objections to the Deductive-Nomological model. Ordinary explanations do not have to meet the requirements of the Deductive-Nomological model, because one does not need to give a law to give a cause, and one does not need to know a law to have good reason to believe that a cause is a cause. As for the notorious over-permissiveness of the Deductive-Nomological model, the reason recession explains red-shift but not conversely, is simply that causes explain effects but not conversely, and the reason a conjunction of laws does not explain its conjuncts is that conjunctions do not cause their conjuncts. (shrink)

The Empiricist or Lockean view says natural kinds do not exist objectively in nature but are practical categories reflecting use of words. The Modern, Ostensive view says they do exist, and one can refer to such a kind by ostention and recursion, assuming his designation of it is related causally to the kind itself. However, this leads to a problem: Kinds are abstract repeatables, and it seems impossible that abstractions could have causal force. In defence of the Modern view, I (...) suggest we can think of kinds as — or as like — ecological niches existing in nature, which are causally effective by virtue of the fact that they predictively determine (some) properties of the things that happen to occupy them. (shrink)

How do we go about weighing evidence, testing hypotheses, and making inferences? According to the model of _Inference to the Best Explanation_, we work out what to infer from the evidence by thinking about what would actually explain that evidence, and we take the ability of a hypothesis to explain the evidence as a sign that the hypothesis is correct. In _Inference to the Best Explanation_, Peter Lipton gives this important and influential idea the development and assessment it deserves. The (...) second edition has been substantially enlarged and reworked, with a new chapter on the relationship between explanation and Bayesianism, and an extension and defence of the account of contrastive explanation. It also includes an expanded defence of the claims that our inferences really are guided by diverse explanatory considerations, and that this pattern of inference can take us towards the truth. This edition of _Inference to the Best Explanation_ has also been updated throughout and includes a new bibliography. (shrink)

Classic studies of explanation, such as those of Hempel and Bromberger, took it for granted that an explanation-seeking question of the form "Why P?" should be understood as asking about the proposition P. This view has been recently challenged by Bas van Fraassen and Alan Garfinkel. They acknowledge that some questions have the surface form "Why P?", but they hold that a correct reading for why-questions should take the form "Why P (rather than Q)?", where Q is a contrasting alternative. (...) This contrast theory is discussed here. It is argued that, properly understood, the contrast theory and the propositional approach can and should give equivalent readings to why-questions. (shrink)

Are explanations contrastive? I argue that any contrastive argument and can be reduced to a non-contrastive one, and hence a theory of explanation need not treat them as an additional kind of explanation.