You see, I've seen the word "rationalism" used to mean all five of these things at different times:
- The belief that we should come to know the world through reason and experimentation, shunning intuition.
- The belief that we should come to know the world through reason and intuition, shunning experimentation.
- The belief that we should come to know the world through knowledge of (and correction for) cognitive biases, and knowledge of (and correct use of) probability theory.
- Being effective at believing things that are true and not things that are false.
- Being effective at doing things that are good and not things that are bad.
Edited to reinstate that proposed solution, since this discussion is presumably finished.
The rationalism-empiricism philosophical debate is somewhat dead. I see no problem in using "rationalism" to mean LW rationalism. "Rationality" (1989) by Rescher defines rationality in the way LW uses the word, but doesn't use "rationalism", ostensibly because of the risk of confusion with the rationalism-empiricism debate. Neither LW nor average people are subject to similar limitations as the academic Rescher, so I think it is prudent to overwrite the meaning of the word "rationalism" now.
Maybe "rationalism" used to mean "rationalism in the rationalism-empiricsm debate", but the concept of "rationality" has become very important during the past century, and that "rationality" means the LW type rationality. Yet, "rationality" is only a method. What LW clearly advocates is that this method is somehow the best, the only right method, the only method, a superior method, or a method that ought to be used. Hence, LW is somewhat founded on a prescriptive belief that "rationality" is a good method. It is very reasonable to call such a belief "rationalism", as someone without belief in the superiority of rationality could still use rationality without being a rationalist.