I tell my writing students that thinking is not the same thing as having thoughts. The first is an action. The second is an acquisition.
The thoughts acquired through thinking are theirs. The rest are secondhand.
Somewhere in their education most students get the impression (perhaps because they have been taught to believe) the point of research is to gather a bunch of expert opinions and to string them together, stretched or shortened to fit whatever page count the assignment requires. I call this the Easter-egg or show-and-tell approach to research, and I spend a good part of any semester discouraging students en masse and individually from taking this approach.
Instead, I tell them, the point of research is to educate themselves about an issue, to be skeptical about what they find (look for the assumptions, verify the facts, weigh the conclusions), and ultimately, on the basis of their newly acquired knowledge, along with what they knew already or thought they knew, assert an opinion that can be supported by accepted facts and valid reasons. That opinion should be theirs, not what they think I want them to believe, not their sources' opinions. In my writing classes, students have the right to express any opinion they can back up for themselves--but only those opinions they can back up.
For me, the whole point of writing is thinking. Writing pushes me to think. Students sometimes complain that if the point of writing is thinking, why the emphasis on grammar and sentence structure? I get their point, but I don't accept their assumption that structure and content are unrelated. Sure, some grammar is just affectation, and I don't emphasize that sort of thing, but most grammar has to do with attention to detail and the more anomalous quality of "getting it right," both of which are essential to thinking.
Feeling, too, is important, but I have little to teach 18 year olds about feeling--except to introduce them to matters, ideas, and attitudes they have probably not encountered before--to show them how new feelings and new tastes may be acquired through curiosity and courage and how to shape their feelings into ideas--mainly through the acquisition of knowledge and the practice of communication.
Also, I'm convinced that sloppy thinking leads to inauthentic feeling--so thinking is a good way to put my feelings to the test.
I'm not sure how one goes about teaching people how to think. I'm successful with some students, unsuccessful with many more. Partly, I suppose, it's by being a thinking person oneself. Partly, it's demanding that people think and not letting them too easily off the hook when they substitute platitudes and bumper-sticker cliches for original thought. Partly, it's developing a curiosity about what other people think, really think, about matters of some importance to everybody. Partly, it's a matter of making oneself and others responsible--for things said as much as for things done--and expecting every opinion to have sound support, whether one approves or disapproves of the opinion.