The other day when work ended, rather than go to my car and drive home as I have every day for the last four years, I just sat outside the building for no reason at all. Maybe I didn't want to go home just yet; maybe I was tired; maybe this maybe that. I sat for about 30 minutes, almost without moving, before finally leaving. I was thinking and thinking about why I did it, and then I started to wonder why I felt anxious about not being able to answer the question. Is it possible we've all been brainwashed into accepting the - if I remember this correctly - "principle of sufficient reason" (assuming this states that all things happen for a reason). Is it possible I sat down for no reason at all?

This principle of sufficient reason (PSR) in its modern form is usually associated with Leibniz, though its origins seem to go much further back. It claims that for anything that exists or for any event, there exists some reason that explains its existence or occurrence. While it has implications for human actions like your own, the PSR is not primarily a psychological theory. It seems to me that for the sake of fulfilling PSR, all we have to say is that the cause of your 'sitting and staring for 30 minutes' is that it happened because you chose to do so. There's probably much more we could say about your actions: maybe you did so because you needed rest, or maybe you had a sub-conscious motive that you were not completely aware of. Like all universal laws/principles, PSR is very difficult to establish with certainty. Even if everything I've observed appears to have a sufficient reason, I can't be certain that I'm correct in attributing those things and events to the reasons I associate with...