Ratiocination

ra·ti·oc·i·na·tion /ˌræʃiˌɒsəˈneɪʃən, -ˌoʊsə-, ˌræti-/ Pronunciation Key - Show Spelled Pronunciation[rash-ee-os-uh-ney-shuhn]
–noun

the process of logical reasoning.

" For all their vaunted powers of ratiocination, grand masters of the chess club seem to be a skittery lot."