Verb
think for oneself (third-person singular simple present thinks for oneself, present participle thinking for oneself, simple past and past participle thought for oneself)
To decide, come to conclusions, or make opinions on one's own, without the help of others
To think for oneself is not only, as Gide said, counterrevolutionary but also apostasy and, at certain times, treason. Eric Hoffer
The Kantian imperative to have the courage to think for oneself has involved a contemptuous disregard for the resources of tradition and an infantile view of authority as inherently oppressive. Terry Eagleton