Psience Quest

The Dappled World: A Study of the Boundaries of Science

Roger Caldwell introduces us to the untidy but realistic world of philosopher of science Nancy Cartwright.

Quote:...If not much that happens in nature is, in fact, as orderly and regular as we have been led to believe by physics, then we must expect even less order when we enter the world of the human sciences. Hence, if the economist attempts to lay down laws, he or she is well-advised to equip them with ceteris paribus conditions – that is, if he proposes that “taxes increase prices” he will protect his hide by informing us that they will only do so if other things are equal. But other things rarely are equal. All kinds of countervailing trends may be at work, as well as quite unexpected events – a run on the dollar, an oil bonanza, a devaluation of the currency – so that it is possible that a tax increase, far from raising prices, may be followed by a fall in prices.

Does this mean that the ‘law’ in this case is wrong? Not at all. In explaining why the law failed to apply on this particular occasion the economist will have recourse to counterfactuals: that is, he will explain that the tax increase would have caused a rise in prices if x or y or z had not occurred. In which case, one may think, it is not much of a law, if it cannot guarantee that the cause will give rise to the effect. However, Cartwright argues that this situation is scarcely peculiar to laws of economics; it applies equally to the laws of physics.

Normally the laws of physics do not come to us armed with ceteris paribus clauses: physicists are rather more confident of the robustness of their laws than are economists. For Cartwright, however, this confidence comes from the fact that, unlike economists, physicists are able, in the closed world of the laboratory, to ensure that the outcomes they predict are in fact attained. They create, that is, the severely restricted conditions in which their predictions will come true. Here Cartwright quotes the econometrician Tyrgve Haavelmo who praises the cleverness of physicists who “confine their predictions to the outcomes of their experiments.” When it comes to predicting things in the real world – the world of avalanches, floods, and earthquakes – the task is somewhat trickier...

Some commentary of interest by Lydia Jaegar:

Nancy Cartwright’s Rejection of the Laws of Nature and the Divine Lawgiver

Quote:Well-known for her thesis that the laws of nature ‘lie’, Cartwright argues for a return to the capacities, conceptually close to Aristotelian natures. The religious references so dispersed in Cartwright’s writings could, at first, lead one to think that her religious influences played a negligible role in the elaboration of her conception of natural order. However, when these few indications are considered alongside biographical information, it becomes clear that the absence of faith in God is of crucial importance, not only to her rejection of laws, but even more so to her adoption of the capacities, and to her preference for the ‘dappled’ world, that is, a world-view that sees unified scientific description as impossible. Thus, Cartwright gives us a significant example of what might well be the paradoxical situation of a certain number of philosophers of science writing in the analytic tradition: the (relative) rareness of references to their religious convictions hides their truly fundamental influence.

No God, No Laws

Nancy Cartwright

Quote:My thesis is summarized in my title, ‘No God, No Laws’: the concept of a law of Nature cannot be made sense of without God. It is not as dramatic a thesis as it might look, however. I do not mean to argue that the enterprise of modern science cannot be made sense of without God. Rather, if you want to make sense of it you had better not think of science as discovering laws of Nature, for there cannot be any of these without God. That depends of course on what we mean by ‘laws of Nature’. Whatever else we mean, I take it that this much is essential: Laws of Nature are prescriptive, not merely descriptive, and – even stronger – they are supposed to be responsible for what occurs in Nature. Since at least the Scientific Revolution they are also supposed to be visible in the Book of Nature, not writ only on stone tablets nor in the thought of God.

My claim here is that neither of these features can be made sense of without God; this despite the fact that they are generally thought to provide some autonomy of the world order from God. I will focus on recent accounts of laws of Nature and describe how the dominant ones fail without the efforts of God; I shall also outline one alternative that tries to make sense of the order of Nature and the successes of modern science without laws of Nature and without immediate reliance on God.