One thing Sartre said a lot was, “I always try to think against myself.” I think this is important to keep oneself from becoming complacent, arrogant, and intellectually flabby. It is challenging your own beliefs and ideas even though you may think you already have the truth. Without challenging yourself, eventually you may even forget the “truth” because you haven’t been thinking about it in so long. Or you may remember what it is you think is true, but have no idea why you think that, and can’t argue for your position.
Sartre changed his philosophy and politics a lot over the years. He’s hard to pin down. But he knew that life is change. Stagnation is death. I think it is interesting that recently, it seems, the accepted definition of a “flip-flopper” has expanded to include anyone who ever changes his or her mind about anything. As if you should, or could even, have all your ideas down pat at the age of majority and never bother to change and grow (or shrink, for that matter!).
To me, a flip-flopper is someone who one day supports position A, and the next day supports position B- all because of what the media polls say or what your friends say or what Tim what’s his name (with Susan Sarandon) or Bill O’Reilly says.
A flip-flopper basically has no mind of her or his own. That is the polar opposite of someone like Sartre, who indeed had a mind of his own, came up with prolific original thought, and changed that thought frequently throughout the years. Not that he ever disavowed his previous writings – he just changed. And, as they say, change is good.