How does our brain direct our behavior?
Let's narrow the question down to something measurable: can brain activity drive a movement? A necessary condition would be to find brain activity that precedes a movement before the muscles start contracting.
Below we see activity from two individual neurons whose activity starts a few seconds before the movement a monkey makes to get a piece of apple. The muscle recordings underneath the neuronal activity show that the carefully trained and monitored monkey is relaxed and initiates each movement anew.