Nicholas Rescher is an enormously prolific writer, with over one hundred books to his name – some might say too prolific, and such a comment would be justified were it not for the consistently high standard of rigour in his work. But certainly a claim of an element of repetition can levelled, and in recent years that may be applied in particular to what might be called Rescher's increasing interest in the methodology of rational thought in general (an inquiry into inquiry) and that of philosophical thought in particular. There has, I think, been a tendency on Rescher's part to move increasingly towards what might be called the second-level study of philosophy – the philosophy of philosophy, or at least a concern for its methods of rational resolution of philosophical issues. A cursory search of the titles of Rescher's books makes this point. Ignorance; Unknowability; Error; Paradoxes; Philosophical Reasoning; Philosophical Dialectics; Dialectics (I'm not sure whether this is the same as the previously mentioned book); Sensible Decisions; Inquiry Dynamics; Cognitive Harmony; Rationality; Reason, Method and Value. One refers to second-level aspects of philosophy with caution, bearing in mind that it is difficult, even perhaps in the end impossible, to distinguish between talking about how philosophy is done and should be done, and simply doing philosophy, since philosophical concerns, as they say, go all the way down. However, Rescher's general theme is how to be rational, and as such, it is a thoroughly worthy one.
Rescher's latest book is in this vein. The book title Aporetics is derived from the Greek aporia meaning impasse or blockage, and deals with identifying what he believes to be a general and uniform method of overcoming a particular kind of inconsistency, aporetic inconsistency, whereby one comes up against a set of inconsistent, but independently plausible, claims. In the light of this, it's rather appropriate that the book reads something like the All-Bran of philosophy – good for you, but somewhat lacking in taste and nutrition.
One possible reaction is to bite the bullet, and accept or ignore such inconsistencies, as Pascal seems to suggest (Rescher refers to this (3)), for the sake of some higher end. But apart from the questionable rationality (perhaps also morality) of this, it may be added that the position is not only uncomfortable, as Rescher says, but impossible in practice to maintain – for when claims are connected to action, and one is forced to act on the basis of accepting one claim rather than another, resolving the aporia rationally becomes inevitable, unless one is prepared to act purely by blind and thoughtless chance one way rather than another – in effect, just toss a coin and go. It's easy to encompass contradictions cheerfully, as Walt Whitman defiantly said he did, if nothing much hangs on whether one resolves them. I could spend my life thinking that 1456 × 553 = 805168, but that 553 × 1456 = 805167, without the inconsistency having any effect whatsoever as long as the non-commutative implication were confined to this sum and not generalised to all arithmetic calculations involving multiplication. However, most people feel the need to resolve most inconsistencies, when they become aware of them. This may be hindered even in the presence of awareness in situations where there are psychological barriers including habit that stand in the way, or when the resolution would involve the rejection of at least one dearly held belief that a person would, for whatever reason, find it difficult to live without, or whose absence is virtually unthinkable for them. Many religious people find themselves in this position, although it is not readily admitted, for to do so would concentrate the mind on resolution at the expense of other things that may be derived from religious belief, and may indeed be anathema to religious belief itself. (This points to what Rescher calls ‘aporetic variation’ – more of which shortly.) Whatever one thinks about the so-called ‘problem of evil’, for example, few religious people are sanguine when contemplating the brute suffering around them while also casting their minds towards their belief in an all-powerful and all-good God; many see how it could be viewed as an inconsistency, even if they also think that at some level there must be some way out of it. Some people indeed seem to be able to carry off Orwellian ‘Doublethink’, whereby one is capable of holding (at least) two contradictory beliefs in one's mind simultaneously and accepting both of them.
The first thing to note is that logic alone is not sufficient to help us resolve aporia. If we have inconsistency, logic tells us only that in order to be consistent something has to be abandoned, but not what (or which) has to be abandoned, or why one claim rather than another should be rejected. This is all part of the adage that logic concerns itself with identifying consistency and contradiction, shows the way to stick with the former, and is not directly occupied with the matter of determining truth or falsity.
So what does Rescher mean by aporia? The first example Rescher gives (2) (there are many examples in the book), alludes to Descartes' thought-experiment regarding a stick partly submerged in water, and is set out as follows:
1. What the sight of our eyes tells us is to be believed.
2. Sight tells us the stick is bent.
3. What the touch of our hands tells us is to be believed.
4. Touch tells us the stick is straight.
Each claim is individually plausible, but they are jointly inconsistent, Rescher claims. In fact, he leaves it to the reader to work out what the joint inconsistency consists of. Presumably it depends upon holding that all the statements are plausibly true, and that therefore because we should believe our eyes, and we should believe our touch, we should believe that the stick is both bent and not bent.
What Rescher proposes for the resolution of aporia ‘is a plausibility analysis that enables the chain of inconsistency to be broken at the weakest link’. (3). The common core of this is a furtherance of Rescher's promotion of epistemic coherentism coupled with pragamatism. He applies this, chapter by chapter, to various fields in which aporetic incoherence can arise: empirical enquiry; counterfactual conditionals; counterfactuals and problems arising from probability; counterfactuals as applied to history; paradoxes; philosophical cases. The application to such cases is neatly summed up in a table towards the end of the book (136). Although he believes that an analysis can be formulated that is ‘general and uniform’ (3), which amounts to that of breaking the incoherence at the weakest point, this also needs to be ‘situationally appropriate’ (133) and this in turn is ‘grounded in the characteristic teleology of the domain’ (137). Different domains give priority to different functional purposes when it comes to the aporetic goal of consistency, and thus it will vary between domains what sort of thing counts as the weakest link. This he calls ‘aporetic variation’ (133). Thus, empirical inquiry gives priority to security, while speculative philosophy gives priority to systematisation. The implication presumably is that, negatively and conversely, the former will sacrifice systematisation for security, while the latter will sacrifice security for systemization. Indeed Rescher draws attention to ‘a fundamental principle of epistemology’ (134) that there is an ‘inverse relationship between the precision or definiteness of a judgement and its security’. This brings to mind a similar claim much used of by Karl Popper (although he is unmentioned by Rescher) in pointing out that bolder theories are more testable, and thus more falsifiable. As the probability of a claim goes up, the scope of the content goes down.
I am sure there are things of value to be taken from this book – although as I have implied in an earlier remark, I did struggle somewhat with the rather dry aspects of its content and presentation. The overall thesis is interesting and powerful however, provided one is prepared to accept the pragmatically-inspired idea of aporetic variation, for without that the thesis that mutually inconsistent but individually plausible claims should be resolved by dropping the weakest claim, becomes trivial.
One small particular quibble – although an all too common one these days – it's a pity about the index, which is inadequate owing to it's being entirely one composed of names.
