Modes of Explanation

In “From modern roots to post-modern rhizomes” (Juarrero, 1993), I explored the alleged transition from mythology to philosophy. Supposedly, what changed with the appearance of pre-Socratic philosophy in the sixth century BC was the logic of explanation deployed to account for natural phenomena. Despite philosophy’s claim to have established a different explanatory logic, I argued in that work that there is nevertheless a unifying thread that did not change from mythology to philosophy: the belief that explanation really explains only when it grounds that which is being explained in a non-phenomenal or non-sensory—call it divine—origin, a source that is also universal, atemporal, and acontextual. The Greek miracle, I claimed, was in fact therefore a “miracle manqué.”

Robustness and explanation are multiply linked. Robustness is crucially connected, as physicist Richard Feynman said, “to fundamental aspects of physical nature.” In his book The Character of Physical Law (1967), Feynman argued that the fundamental principles of nature are remarkable because they are derivable in multiple ways using multiple different assumptions. So in some sense they are almost unavoidable. This he related to a “Babylonian” architecture of theory, in which various elements of theory are multiply connected, redundant, and thus more reliable. For this reason, fundamental physical laws do not depend on any particular assumptions; a fact that he illustrated with two different independent derivations of the inverse-square law of gravitational attraction. The great conservation laws in physics have this character, and much of the progress in nineteenth-century physics progressed through the discovery of the interconvertibility of different forms of energy. The conservation laws are, for this reason, deeply anchored in the explanatory frameworks that we would use even for deciding what is a reasonable explanation and what is not.

I have recently been working with a form of one of Hempel’s (1962) two modes of explanation: the subsumption of phenomena under a covering law model. The form in question is the subsumption—or equivalently, specification—hierarchy (Salthe, 2012), thus, for example:

{class of more general universals {{{nested subclasses of more definite particulars}}}}

Ockham’s razor says: “Choose the simplest theory compatible with the data.” Without Ockham’s razor, theoretical science cannot get very far, since there are always ever more complicated explanations compatible with current evidence. Scientific lore pretends that reality is simple—but gravitation works by a quadratic, rather than a linear, law; and what about the shocking failure of parity conservation in particle physics? Ockham speaks so strongly in its favor that demonstrating its falsity resulted in a Nobel Prize in physics (Lee and Yang 1957). So why trust Ockham?

I believe that we are in a much stronger position now than we have been for many years, provided that we are:

This is a question that perhaps only philosophers, religious thinkers, literary writers, and a few physicists might seriously ponder. (No doubt others ponder it, but less systematically.) Here are two different answers: (1) the world is completely intelligible; (2) the world is not completely intelligible. The first answer is given by some physicists (who believe that string theory provides a “theory of everything” that makes the world completely intel-ligible¹) and by some philosophers influenced by the “unity of science” program started in the 1930s (who believe that there must be some “theory of everything,” whether or not it is string theory, cf. Chalmers, 2012). An extreme form of the second answer would be given by skeptics who say that nothing is intelligible, either because the world itself is completely random and disorderly (“as flies to wanton boys are we to the gods” to quote King Lear), or because, even if the world is orderly we can never know and therefore understand what this order is (“How unsearchable are His judgments, and His ways past finding out,” Romans 11.33). A moderate form of the second answer would be that some things about the world are intelligible, others not. A religious scientist might hold such a position. So might some philosophers, who think that not all mental states can be reduced to, and understood in terms of, physical ones—the gold standard of intelligibility for physicalists (Kim, 2005). A somewhat different answer is given by Nagel (2012) in a recent book, which is that whether or not the world is in fact completely intelligible, “science is driven by the assumption” that it is.