""ratiocinatory?

Don, you must have made that word up.

I salute you.""

Not guilty, I'm afraid Leeneia.

From the OED        

ratiocinate

Pronunciation:/ˌratɪˈɒsɪneɪt, ˌraʃɪ-/
verb
[no object] formal

    form judgements by a process of logic; reason.

Derivatives

ratiocination
Pronunciation:/-ˈneɪʃ(ə)n/
noun
ratiocinative
Pronunciation:/-nətɪv/
adjective
ratiocinator
noun

Origin:

mid 17th century: from Latin ratiocinat- 'deliberated, calculated', from the verb ratiocinari, from ratio (see ratio)

I'm just a mine of useless information, according to 'er indoors.

Don T.