For a person of average rationality skills, all arguments beyond a certain inferential distance are dangerous because they are unable to determine their validity; many of the arguments sound right and yet the conclusions seem unintuitive. Those who allow themselves to be persuaded by such arguments can commit completely illogical or amoral actions.
I think in this light the similarity of the words "rationalization" and "rationality" makes sense for use by the common person for whom any naive attempt at rationality would do more harm than good.
That's not to say that such people couldn't benefit from adopting a particular rationalist strategy, for example, using expected value calculations when gambling (or rather not gambling); it's pure reasoning from actions to consequences that is too dangerous to attempt.
Today's post, Rationalization was originally published on 30 September 2007. A summary (taken from the LW wiki):
Rationality works forward from evidence to conclusions. Rationalization tries in vain to work backward from favourable conclusions to the evidence. But you cannot rationalize what is not already rational. It is as if "lying" were called "truthization".
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