S: (v) speculate (talk over conjecturally, or review in an idle or casual way and with an element of doubt or without sufficient reason to reach a conclusion) "We were speculating whether the President had to resign after the scandal"
S: (v) reason (think logically) "The children must learn to reason"
S: (v) think, cogitate, cerebrate (use or exercise the mind or one's power of reason in order to make inferences, decisions, or arrive at a solution or judgments) "I've been thinking all day and getting nowhere"
S: (v) think, opine, suppose, imagine, reckon, guess (expect, believe, or suppose) "I imagine she earned a lot of money with her new novel"; "I thought to find her in a bad state"; "he didn't think to find her in the kitchen"; "I guess she is angry at me for standing her up"