Like many others I don't care much for the word 'rationalist', since it comes with lots of preexisting negative connotations. I think we're most likely stuck with the term, but to amuse myself, I came up a list of alternative terms. The Seattle LW group enjoyed the word 'cognomancy'.
- cognomancer
- optimancer
- orthomancer
- ratiomancer
- logimancer
- utilimancer
- mentamancer
- metamancer
- economancer
- psychomancer
- bayesian empiramancer (really you could add 'bayesian to most of these')
- mathamancer
- cognitive engineer
- optimization engineer
- neuromancer
- cognologist
- cognician
- optimician
- utilitician
- ratician
- orthocognician
- economician
- mentician
- empirician
Fun!
I like a lot of the -mancers too (and apparently the letter n), like cognomancer, and optimancer (mostly because it's so close to optimizer). I think my favorite on your list is cognician.
To throw in some more...
(From the Greek "Nike" for Victory (or, winning):
nikosopher
nikomancer
nikologist
From Aletheia (Greek for Truth):
aletheisopher
alethologer
From Veritas (Latin for Truth):
veritician
veritosopher
veritimancer
veritologer
From ingenium:
ingenian
wingeneer
And others:
noomancer
noocian
neostoic
I also apparently like the letter n.
You made me think of: win-gineer.