Anders Sandberg’s post last week prompted a debate on the role of intent in explaining behaviour.  Anders would give significant weight to conscious stated goals, while some commenters preferred the economic methodology of ignoring stated goals and assuming behaviour is ultimately based on self-interest.

Perhaps evolutionary psychology can help reconcile these positions.  The evolutionary methodology, like the economic methodology, takes self-interest to be the ultimate motivation.  But, as Richard Alexander and Robert Trivers have pointed out, being deceived is disadvantageous, which implies that there will be selection to be good at spotting deception, which implies that there will be selection in favour of self-deception.  In short, the best way to lie convincingly is to believe your own lie.  For that reason, there is often likely to be a mismatch between stated and actual (ultimate) motivations; people are likely to posit noble objectives in the pursuit of their own self-interest. 

But this doesn’t imply that intentions are no more than self-deception.  Ignore intent for the moment and suppose that others draw conclusions about my motives simply from observing my behaviour. Suppose that to achieve my self-interested objectives, I have to fool you into thinking that I’m not self-interested.  Since you draw inferences solely from my actions, that means I have to act in a way that is not self-interested.  And from your perspective, that is no different than if I am not in fact entirely self-interested.  Though this argument may appear circular, it isn’t.  It implies that my actions will balance my direct self-interest with my need to deceive you.

Adding intent doesn’t change the basic reasoning, if we acknowledge the role of self-deception and accept that human actions are mediated by conscious and subconscious thought.  To achieve my self-interested objectives, I have to fool you into thinking that I’m not self-interested.  To do that I have to fool you into thinking I don’t intend to be self-interested.  To do that, I have to intend not to be self-interested.  And if I don’t intend to be self-interested, I won’t (always) act in a self-interested manner.  Again, this isn’t entirely circular, since self-deception that is too effective would defeat its own purpose.  The argument implies that my actions will reflect both my conscious intent and my self-interest in a way that balances my need to convince you of my noble motives with a need to achieve my self-interested ends.  This means that even though self-interest is more fundamental, both intent and self-interest must be considered in order to adequately explain/predict behaviour. 

There is a refinement worth mentioning.  Even though on average people will optimally balance deception and self-interest, it is unlikely that each individual will strike the optimal balance. Instead, behaviour will be distributed in a range centered on the optimal balance.  Some individuals will be far outliers on the distribution.  These will include the saints and fanatics who motives may be truly inexplicable by self-interest.