Mister Volition is a short story in the sci-fi genre by Greg Egan, available in the Luminous collection of stories.
The antihero mugs someone in order to steal his eye patch: a piece of biofeedback electronics that superimposes information about you over your senses, as specified by whatever software it's running. He obsesses about his freedom to do anything, at the cost of anyone else's rights. Trying out the patch, it shows him exactly how his own mind works: the thought associations, the patterns. The protagonist wants to prove that his mind is still in control, but the patch unravels this concept, revealing his mind to be nothing more than an elaborate, automated system. It shows that choice is an illusion.
This story is just as much about philosophy of mind as it is about a hypothetical piece of future technology or interaction between characters. The author seems to subscribe quite heavily to physicalism, and indeed the note at the end of the story directs readers to Consciousness Explained and The Society of Mind.
All in all, a good read, more because it makes you think than because of the plot.