1There are several alternative ways to characterize natural laws. For an overview, see Hooker (1998). If one is a Humean, then the Humaean mosaic itself does not seem to allow any other explanation. Since this is the ontological foundation in which all other existing things must be explained, none of these other things can really explain the structure of the mosaic itself. This complaint has been expressed for a long time, usually as an objection to any humane presentation of laws. If laws are nothing more than generic features of the Humenic mosaic, then there is a sense in which these same laws cannot be invoked to explain the particular characteristics of the mosaic itself: laws are what they are by virtue of the mosaic and not the other way around (Maudlin 2007, 172). Several general properties of scientific laws, especially when they relate to the laws of physics, have been identified. The second thesis, which constitutes the core of the moral theory of natural law, is the assertion that the norms of morality are somehow derived or implied by the nature of the world and the nature of man. St. Thomas Aquinas, for example, identifies the rational nature of man as what defines the moral law: “The domination and measure of human actions is reason, which is the first principle of human action” (Thomas Aquinas, ST. I-II, Q.90, A.I). Since humans are rational beings by nature, it is morally appropriate that they behave in a manner consistent with their rational nature.
Thus, Thomas Aquinas draws the moral law from the nature of man (i.e. from the “natural law”). A popular answer concerns being a law on deductive systems. The idea dates back to Mill (1843, 384), but has been defended in one form or another by Ramsey (1978 [f.p. 1928]), Lewis (1973, 1983, 1986, 1994), Earman (1984) and Loewer (1996). Deductive systems are individualized by their axioms. The logical consequence of axioms are theorems. Some true deductive systems will be stronger than others; Some will be simpler than others. These two virtues, strength and simplicity, compete.
(It is easy to make a system stronger by sacrificing simplicity: include all truths as axioms. It is easy to simplify a system by sacrificing power: it is enough to have the axiom that 2 + 2 = 4.) According to Lewis (1973, 73), the laws of nature belong to all true deductive systems with a better combination of simplicity and strength. For example, the idea that it is a law that all uranium balls are less than a mile in diameter is because it is probably one of the best deductive systems; Quantum theory is an excellent theory of our universe and could be among the best systems, and it is plausible to think that quantum theory plus truths describing the nature of uranium would logically mean that there are no uranium balls of this size (Loewer 1996, 112). It is doubtful that the generalization that all golden balls are less than a mile in diameter would be among the best systems. It could be added as an axiom to any system, but it would bring little or nothing of interest in terms of strength and it would sacrifice something in terms of simplicity. (Lewis subsequently made significant revisions to his narrative to solve problems of physical probability (Lewis 1986, 1994). In practice, there is evidence that there is a persistent mismatch between what is predicted by a law of nature and what is actually observed (see, for example, Cartwright, 1983; Mitchell, 1997). In our example above, given the initial conditions, it is very unlikely that the acceleration of the object is exactly 5 m/s2, because disturbing factors (such as air resistance or other forces) still act on the object, even under highly controlled conditions. In response to this problem, advocates of the traditional view argue that if we could account for all the confounders and add them all up, we would actually get a perfectly accurate prediction, even if it`s almost never a practical possibility. Laws differ from scientific theories in that they do not postulate a mechanism or explanation of phenomena: they are merely distillations of the results of repeated observations.
As such, the applicability of a law is limited to circumstances similar to those already observed, and the law may prove erroneous when extrapolated. Ohm`s law only applies to linear lattices; Newton`s law of universal gravity applies only in weak gravitational fields; early laws of aerodynamics, such as Bernoulli`s principle, do not apply in the case of compressible flow, as occurs in transonic and supersonic flight; Hooke`s law applies only to strains below the yield strength; Boyle`s law applies with perfect precision only to ideal gas, etc. These laws remain useful, but only under the specified conditions under which they apply. Sometimes the idea that laws play a particular role in induction serves as a starting point for a critique of humeic analyses.
