Non-factual Criteria

Abstract

Cases of conflict, between alternative theories and even between alternative forms of description, often occur in science. For example in discussing the disconfirmation of theories in the last chapter I mentioned the current dispute between alternative theories of boundary absorption between which, at the moment, there are no ascertainable differences of fact, except the evidence of the direct investigations of Fage and Townend. As far as their power of predicting absorption rates is concerned either theory gives the correct results. How do we choose between them? Danckwerts in summing up his reasons for rejecting the stagnant film hypothesis says, very noncommittally, that commonsense grounds counsel its rejection, for it is not a reasonable model. It does not postulate the sort of thing we could reasonably be expected to accept as an underlying mechanism of transfer. This sort of judgement is extremely important from a practical point of view but must be passsed over by the logician for there is no question of giving a general account of ‘what one could reasonably be expected to accept’, for this is compounded of one’s experience, one’s previous knowledge, the state of development of the field in which one is working, and other imponderables of the kind.