is a specific kind of: cerebrate, cogitate, think.

is a broader term that covers: induce | deduce, deduct, derive, infer | syllogise, syllogize | feel, find | deduce, infer | gather | extrapolate, generalise, generalize, infer.

derivation: conclusion, decision, determination | intellect, reason, understanding | ground, reason | ratiocinator, reasoner | rationality, reason, reasonableness | conclusive.