Skinner, a behaviorist psychologist, claimed that "free will is but an illusion"; that is, all actions are brought on as a direct result of conditioning, be it operant or classical. Skinner was quick to dismiss internal processes as irrelevant, claiming only observable behavior matters (this is a basic tenet of behaviorist psychology). Other behaviorists say environment doesn't totally predicate behavior, as one change alter their environment, becoming the impetus of their new actions. But Skinner's ideas still carry much weight, and I'm interested in seeing what you guys have to say about this.
I would put this in Serious Discussions, but I'm interested in reading some anecdotes that might not fit there.