Rationality, like/possess it or not, plays a major role in determining the kind of life that we all lead. Rationality is that faculty of mind that we use to make decisions about day to day choices, what beliefs to hold and which world views to adopt (at least this is true for anyone that does not subscribe to radical cognitive-determinism). Alongside emotional and random brain processes, it is responsible for many of the decisions we make and thus shapes our life paths. As far as decision-making faculties go, rationality is a goodun': via processes of inference and deduction, our rationality helps us to make the best possible decisions with the (often limited) information that we possess.
Or at least that is what we might assume.
The prisoners' dilemma is a hypothetical game played between two people, each of whom seek the best possible outcome for themselves via rational decision-making. Imagine that two acquaintances are caught by the police trying to smuggle drugs into the country. They are placed in separate interrogation chambers and each told that when it comes to their trial they will be given the option of confessing or remaining silent. However, the resulting prison sentence will depend not just on their own decision but on that of their acquaintance. If both players remain silent there will not be enough evidence to charge them with drug smuggling and each will be convicted of the lesser crime of weapon possession and will land 1 year in prison. If both players confess they will be convicted of drug smuggling and each will land 5 years in prison. However, if one player confesses and the other does not, the player that confesses will be released with no sentence for turning evidence against his acquaintance, while the player that remains silent will go to prison for 10 years. The game is represented below.
Knowing that his acquaintance will have to make a decision at the same time as himself, what does the player's rationality tell him is the best decision to make? Notice that regardless of what the other player chooses, it seems that the best choice for a player is to confess. If player 2 is definately going to remain silent, then player 1 ought to confess because he will get to go free, as opposed to spending 1 year in prison. If player 2 is definately going to confess then player 1 ought to confess also because this lands him only 5 years in prison compared to the 10 years he would get if he remained silent. Thus, rationality tells each player that the best option is to confess.
Yet if we look at the game again, we see that the best outcome for the players does not occur if both confess. The best outcome for both players is if they both remain silent (they receive 1 year each as opposed to 5 years each). If rationality tells us what is best for us, how can it be so wrong in this situation?
There are many answers to this: rationality only works in a world in which there is perfect information (we don't have that here, neither player knows what the other is going to choose); rationality is not in fact the best guide for our actions; the most rational option is actually to remain silent, not to confess. Each of these has its merits (and flaws), but each has been touted before. I propose that to exercise our rationality properly, we must consult the 'moral law'.
Immanuel Kant, often considered the most important firgure in enlightenment rationalism (though he expounded empiricist tennets also), suggests that our rationality naturally brings us to the moral conclusion that we should always "Act according to a maxim which can be adopted at the same time as a universal law" (Kant, Groundwork for the Metaphysics of Morals). That is, we should always act in such a way that if anyone else were in our position, it would be best for them to act in this way also. What does this imply for the prisoners' dilemma? Well, we must ask ourselves, what decision is the one that would be most rational to make if everyone else were to make that decision also? Obviously, the answer is to remain silent: if all players were to make this decision also, this would lead to the best outcome for everyone. If all players remain silent, all players receive 1 year in prison as opposed to 5. (Of course, this outcome hinges on the assumption that all people arrive at Kant's morality via their rationality. We might not think this to be the case in the real world, but in the prisoners' dilemma we assume that each player reasons similarly.)
As a product of truly rational thinking Kant's categorical imperative (also referred to as "The Golden rule" [do unto others as you would have them do unto you], though this is not how Kant in fact preferred his thoughts to be interpreted), shows us why it is not in fact irrational to be rational in the prisoners' dilemma. One would only think that this was the case if they did not realise that moral thinking is in fact a part of rational thinking. But one can hardly reject the result that morality is a natural conclusion of rationality, for it does indeed produce the best outcome for each individual.
Why are such thoughts at all important or relevant to modern life? I hear you ask. Morality is so last century, I hear you sneer. I'm all about me, man.
The fact of the matter is, examples - and well reasoned solutions - like the prisoners' dilemma show that even if we are truly only concerned with ourselves (the selfish bastards that we are), it pays to be moral. Not only does society at large do better with a system of morality, individuals themselves do better than they otherwise would by following a rational system of moral conduct.
Hence, next time you're thinking about throwing shoes at your friend's wall, vomiting in someone else's bed or shitting in his or her shower, consider whether this is really in your best interests. If you do not heed the rational call of morality, you might find that your life is "solitary, poor, nasty, brutish and short" (Hobbes, Leviathan).
- J. A. Graham