Christpher John Francis Boone, the narrator of Mark Haddon’s The Curious Incident of the Dog in the Night Time has an unusual method for deciding what sort of a day he’s going to have. Good Days are days on which he passes four red cars in a row in the bus on the way to school in the morning. Three red cars in a row makes for a Quite Good Day, five a Super Good Day. If there are four yellow cars in a row, however, then he will have a Black Day, a day when I don’t speak to anyone and sit on my own reading books and don’t eat my lunch and Take No Risks.

Christopher does not have internal moods, or respond sympathetically to external conditions such as changes in the weather, in quite the way that most other people seem to. Nevertheless, he has the same need as other people for a way to differentiate Super Good Days from Black Days, the same need for there to be some pattern, some rhythm, to his days. You can’t just go on having Super Good Days all the time. Christopher creates his own system, based on simple pattern recognition, for introducing arbitrary variation into his life.

Making reasoned decisions, and consequently acting deliberately, is conventionally opposed to being impulsive and acting arbitrarily. Whims and impulses are real, motivating forces in our mental lives, although the behaviour they induce in us is often considered thoughtless. Hesitation, deliberation, thinking things over, are at the very least prudential values: they have to do with staying out of trouble, avoiding actions that may have regrettable consequences. In spite of this prudence, on Good Days we do sometimes take risks, act on impulse, make blind leaps into the unknown. Arbitrariness can be useful: it can prevent us from getting stuck in a fixed pattern of behaviour, doing what is sensible and realistic only within the limited reality with which our senses are familiar.

There is a line of thinking about conscious decision-making that suggests that one of the recurring problems we have when trying to make rational decisions is that there is too much, rather than too little, information available for us to take into account. It might not be possible to weigh up all of the considerations that bear on our decision: there might be more relevant factors than we know what to do with. Daniel Dennett makes the case for coin-flipping in such scenarios as follows:

[I]t is (higher-order) rational of us to cede a bit of our (lower-order) rationality in the interests of efficient, speedy decision making. The “cost” is a slight risk of overlooking truly compelling and important reasons for one course of action over another. The “benefit” is avoiding the otherwise large risk of deliberating too long and missing the deadlines for meaningful action.

(Elbow Room, p. 69)

Other theorists of consciousness have argued that the pre-rational substrata of the human brain play a decisive role in enabling the rational mind to arrive at its conclusions - that without the input of the drives, the emotional and unreasoning aspects of our personalities, the process of deliberation would never conclude (or, possibly, get started in the first place). It is not - we hope - simply the case that rational deliberation is a kind of “book-keeping” for a decision that our baser motives have already made for us (although what we call “rationalisation” may very well be something of the sort). But rational reflection, while it is part of the circuit - in the loop - of the decision-making process, neither supplies the juice nor determines, all by itself, the final verdict.

Regardless of the neuroscientific particulars, a pragmatic account of the decision-making process is likely to acknowledge not only the unfortunate inevitability, but also the constructive value, of a certain arbitrariness. This does not in any way lessen the sense of duty we may feel to be reasonable, to reason things out, to base certain of our actions on well-informed and painstakingly-considered deliberation. Nor does it imply that we are deluding ourselves if we think that all of this higher-order rationality will do us any good. But it is clear that when we say we wish for certain of our decisions to have a rational basis, we cannot mean that we wish for them to be purely and simply caused by the existence of reasons from which, given a suitably rigorous and comprehensive and calculus, they would have been ineluctibly derived. (In what sense, if this were so, would they even be our decisions? In what sense could we be held accountable for them?)

So again to Derrida, and this time to the ethics of deconstruction and the experience of justice (as decision, or arbitration) as an experience of the impossible. We urgently do not wish to regard our decisions as purely arbitrary, or our deliberative rationality as a mere mask for our impulses (base or not), and so it makes sense for those who want to erect a philosophical scarecrow (or mad axeman-in-effigy) over the tomb of Derrida to represent his thinking on these matters as a sort of sub-Nietzschean gloating over the homage our vices pay to our virtues.

This is what underlies a certain denunciation of postmodernism (somehow including Derrida, who was in fact neither a postmodernist nor even - as, say, Lyotard might be said to have been - a philosopher of the postmodern) as a movement that accused Enlightenment rationality of being a conceit masking the fundamentally arbitrary expression of power. It is not, I think, Enlightenment rationality that we most care about (at least, there are plenty of people who wish to be able to be thought of as capable of rational deliberation, who either have never heard of Enlightenment rationality or have only the fuzziest notion of what it means). But what this fabricated hanging-judge’s version of postmodernism represents is the apparently very seductive - yet necessarily morally unconscionable - notion that nothing that happens in the frontal lobes of your brain matters a jot: that what you (or power) want to do is, inevitably, what you (or power) will do, and then if you are very clever and civilised and Western make up elaborate (perhaps even Kantian) excuses for having done.

As Derrida was not, in fact, Aleister Crowley, we can perhaps resist this attempt to daub the mark of the beast on his forehead (a difficult feat to accomplish in absentia but there is certainly a lot of grubby finger-waving going on at the moment). Derrida insisted that the outcome of a decision was not a given, that the making of a decision must proceed not only in the absence of sufficient information to make it a sure thing, but in the face of an insurmountable contradictory excess of reason(s) - the aporia that deconstruction is well-known for insisting on discovering everywhere. That is what makes each decision, each time, the singular responsibility of whoever makes it; it is why I myself, and not the person who taught me moral calculus at school, am responsible for my mistakes.