cogitate -
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"
think out consider carefully and rationally; "Every detail has been thought out"
dream up,
think up,
concoct,
hatch,
think of devise or invent; "He thought up a plan to get rich quickly"; "no-one had ever thought of such a clever piece of software"
pass judgment,
evaluate,
judge form a critical opinion of; "I cannot judge some works of modern art"; "How do you evaluate this grant proposal?""We shouldn't pass judgment on other people"
meditate,
contemplate,
study consider as a possibility; "I contemplated leaving school and taking a full-time job"
plan make plans for something; "He is planning a trip with his family"