Disagreements about the criteria of a law should not dismay us at the outset. As Wittgenstein taught, many of our concepts are cluster concepts -- they have an associated cluster of criteria, of which only most need be satisfied by any instance. The more of the criteria are met, the more nearly we have a clear case. This vagueness does not render our concepts useless or empty -- our happiness here as elsewhere depends on a properly healthy tolerance of ambiguity. Let us begin with the point that universality is not enough to make a truth or law of nature. No rivers past, present, or future, ar rivers of Coca-Cola, or of milk. I think that this is true; and it is about the whole world and its history. But we have no inclination to call it a law. Of course we can cavil at the terms river, Coca-Cola, or milk. Perhaps they are of earthly particularity. But we have no inclination to call this general fact a law because we gard it as a merely incidental or accidental truth. Therefore we will have the same intuition, regardless of the terms employed. The most innocuous link between law and necessity lies in two points that are merely logical or linguistic. The first is that if we say that something is a law, we endorse it as being true. The inference (1) It is a law of nature that A Therefore, A is warranted by the meaning of the words. This point may seem too banal to mention-- but it turns out surprisingly, to be a criterion which some accounts of law have difficulty meeting. One observes of course that the inference is not valid if of nature is left out, since societys laws are not always obeyed. The second merely logical point is that the locution It is a law that is intensional. Notice that the above inference pattern (1) does not remain valid if we replace a law of nature by true. But something important has changed when we do, for consider the following argument: (2) It is true that all mammals have hair. All rational animals are mammals. Therefore, it is true that all rational animals have hair. This is certainly correct, but loses its validity if we now replace true again by a law of nature. The moon orbits the earth and must continue to do so, because of the law of gravity. This illustrates the inference from It is a law that A to It is necessary that A; but this must be properly understood. Logic does not require what is necessary to be necessarily necessary. More familiar is the idea that there are many different ways the world could have been, including differences in its laws governing nature. If gravity had obeyed an inverse cube law, we say, there would have been no stable solar system-- and we dont think we are contemplating an absolute impossibility. But we could be wrong in this. Of course, if laws are themselves necessary truths, their consequences would inherit this necessity. Therefore the strong criterion of necessity inherited entails that of necessity bestowed. And since what is necessary must be actual, the criterion of necessity bestowed entails that of inference. That there is gravity is the reason why the moon continues to circle the earth. The premiss that there is such a law is therefore a good basis for prediction. The second traditional argument that if we deny there is such a reason, then we can also have no reason for making that prediction. We shall have no reason to expect the phenomenon to continue, and so begin no position to predict. A problem with this argument is that we cannot be so ready to equate having reason to believe that A with believing that there is a reason for A... Consider the following.. Whatever is A must be B Therefore, if this thing is (were) both A and C, then it is (would be) B. But can all conditionals derive from necessities in this way? Consider: if i had struck this match, then it would have lit. It does not follow that if I had struck this match, and it had been wet at the time, then it would have lit. Nor, if I agree that the latter is false, do I need to retract the former. I can just say: well, it wasnt wet. We see therefore that counterfactual conditionals violate the principles of reasoning which govern strict or necessary conditions. Goodman wanted to relate this to laws. We can, he said, support a counterfactual claim by citing a law. But in the mid-1960s Robert Stalnaker extended an analysis of David Lewis. Unfortunately for laws, this analysis entails that the violations of those principles of inference that work perfectly well for strict conditionals are due to context-dependence. Science by itself does not imply these more interesting counterfactuals; and if laws did then they would have to be context-dependent. According to Nancy Cartwrights stimulation account of science, the phenomenological laws are applicable but always false; the basic principles accurate but never applicable. It is therefore not so easy to reconcile science as it is with the high ideals of those who see it as a search for the true and universal laws of nature.
Posted on: Fri, 08 Aug 2014 02:35:14 +0000