Verisimilitude revisited

The problem of truthlikeness (verisimilitude, nearness to the truth) has been described as one of the most fundamental problems in philosophy of science. The scientist is not someone who knows the truth. Rather, he trafficks in falsehoods: what he has to offer are conjectural theories which represent better of worse approximations to the truth. Thus when we judge one theory superior to anc, ther we cannot mean simply that while the latter theory is false the former is true. For, more likely than not, the superior theory will also be false. What we mean is rather that the better theory is one which is closer to the troth, which diverges from the truth less than the other theory does. There seem absolutely obvious cases of one statement's being nearer to the truth than another. The man who maintains that there are exactly eight planets in the Solar System is undeniably closer to the truth than his opponent who insists that there are only five. It is not immediately obvious, however, how to abstract from such intuitively indisputable cases a definition which would state in general terms precisely what it takes for an arbitrary sentence to be closer to the truth than another sentence of the same language. A definition of this sort was proposed and argued for by the present author in [6] ~aad [7]. Since its publication the proposal has come under a barrage of strictures ranging from charges of intractability and material inadequacy to sweeping declarations of the general undesirability of explicating intuiLtive notions in the first place (See [2], [3], [4], and [51 ). The aim of the present article is three-fold. Firstly, I want to rehearse my theory in very simple terms in order to show that, bereft of technicalities necessitated by mathematical rigour and generality, the definition is extremely simple and perfectly natural. Secondly, I shall correct an error which flaws the definition as originally formulated in [7]. Thirdly, I shall defend the proposal against charges of material inadequacy made by Popper, Niiniluoto, and Miller.