One of the central myths of rationality is that if we use it properly, we can do away with the need for personal, subjective judgement. It is always rebarbative to the philosopher to reach a point in an argument where it is necessary to admit that others may be presented with the same chain of inferences yet justifiably reach a different conclusion. The intolerability of this is implicit in Plato’s idea of ‘following the argument’ and has been most explicit in the rationalist tradition, where Descartes talked of following the ‘natural light’ of reason, and Spinoza set out the argument of his Ethics as a set of quasi-mathematical deductions. It also emerges in twentieth-century analytic philosophy – the dominant tradition in Britain and North America – which put the learning of symbolic logic at the heart of the undergraduate curriculum. Students were encouraged to believe that if they could translate their arguments into the language of logic they could neatly divide those that could be decreed objectively sound and those that were fallacious.
The dream that many philosophers have had is of a form of reason in which subjective judgement is banished and everything that matters can be demonstrated with the rigour of an algorithm. Reason leads to one correct conclusion and one only. Given this high benchmark, it is perhaps not surprising that many have taken the fact that it hasn’t been reached as evidence that rationality has been seriously overrated. For instance, it has been creditably argued that in science the observed facts always, or at least almost always, fit more than one possible theoretical explanation. Ideas like these have led some to more extreme positions in which scientific knowledge is dismissed as having no special status and as just another human construct or narrative.
If we are to save a realistic yet robust notion of what it means to be rational, we need to debunk the myth that reason requires no judgement without leaving ourselves reliant on subjective opinions that cannot be rationally criticised or examined by others. This is the purpose of the first part of this book, which will focus on the use of reason in religion and science. In these and in other domains of reasoning, there is an ineliminable role of judgement, but that does not entail a debilitating skepticism about reason and rationality.