Indeed - that was my first thought, but I was waiting till I figured out a good way of stating it. RH's definition of 'rational' seems to go against the usual definition presented above, while EY's seems to embrace it.

A common example of where rationality and truth-seeking come into conflict is the case where organisms display their beliefs - and have difficulty misrepresenting them. In such cases, it may thus benefit them to believe falsehoods for reasons associated with signalling their beliefs to others:

"Definitely on all fronts is has become imperative not to bristle with hostility every time you encounter a stranger. Instead observe him, find out what he might be. Behave to him with politeness, pretending that you like him more than you do - at least while you... (read more)

10Eliezer Yudkowsky11yMy definition differs from the one in Wikipedia because I require that your goals not call for any particular ritual of cognition. When you care more about winning then about any particular way of thinking - and "winning" is not defined in such a way as to require in advance any particular method of thinking - then you are pursuing rationality. This, in turn, ends up implying epistemic rationality: if the definition of "winning" doesn't require believing false things, then you can generally expect to do better (on average) by believing true things than false things - certainly in real life, despite various elaborate philosophical thought experiments designed from omniscient truth-believing third-person standpoints. Conversely you can start with the definition of rational belief as accuracy-seeking, and get to pragmatics via "That which can be destroyed by the truth should be" and the notion of rational policies as those which you would retain even given an epistemically rational prediction of their consequences.

The Costs of Rationality

by RobinHanson 1 min read3rd Mar 200981 comments


The word "rational" is overloaded with associations, so let me be clear: to me [here], more "rational" means better believing what is true, given one's limited info and analysis resources. 

Rationality certainly can have instrumental advantages.  There are plenty of situations where being more rational helps one achieve a wide range of goals.  In those situtations, "winnners", i.e., those who better achieve their goals, should tend to be more rational.  In such cases, we might even estimate someone's rationality by looking at his or her "residual" belief-mediated success, i.e., after explaining that success via other observable factors.

But note: we humans were designed in many ways not to be rational, because believing the truth often got in the way of achieving goals evolution had for us.  So it is important for everyone who intends to seek truth to clearly understand: rationality has costs, not only in time and effort to achieve it, but also in conflicts with other common goals.

Yes, rationality might help you win that game or argument, get promoted, or win her heart.  Or more rationality for you might hinder those outcomes.  If what you really want is love, respect, beauty, inspiration, meaning, satisfaction, or success, as commonly understood, we just cannot assure you that rationality is your best approach toward those ends.  In fact we often know it is not.

The truth may well be messy, ugly, or dispriting; knowing it make you less popular, loved, or successful.  These are actually pretty likely outcomes in many identifiable situations.  You may think you want to know the truth no matter what, but how sure can you really be of that?  Maybe you just like the heroic image of someone who wants the truth no matter what; or maybe you only really want to know the truth if it is the bright shining glory you hope for. 

Be warned; the truth just is what it is.  If just knowing the truth is not reward enough, perhaps you'd be better off not knowing.  Before you join us in this quixotic quest, ask yourself: do you really want to be generally rational, on all topics?  Or might you be better off limiting your rationality to the usual practical topics where rationality is respected and welcomed?