Razor Arguments

Often when Ockham's razor is invoked nothing more specific is intended than the general principle that simpler theories are on the whole more probable than less simple ones. Before considering the razor itself, it is worth examining first the more general principle, often called parsimony. Readers are warned, however, that simplicity is complicated, which is one reason for preferring more specific razor arguments. Consider omphalism, the hypothesis expounded by Phillip Gosse in 'Omphalos' (1857), that the universe was created by God in 4004 BC, complete with fake traces of earlier times, such as the fossil record. Any putative empirical evidence against omphalism, such as the direct naked-eye perception of the Clouds of Magellan some tens of thousands of years in the past, is question-begging. Nonetheless most of us judge omphalism to be highly improbable, and, if asked why, we might well invoke the name of Ockham, but Ockham's razor is, strictly speaking, the dictum that, "entities are not to be multiplied more than is necessary," and Gosse wielded the razor like Sweeney Todd. What is intended is rather that simpler theories are on the whole more probable. This may also be used to underpin the rule of inference to the best explanation. For other things being equal the simpler explanation is the better.