Here's the real kicker though... You might say, "but everything isn't caused by something else, especially at the sub-atomic level." There are super tiny particles that are as unpredictable as far as we understand it. They appear to be random and have no governing principles. There are two issues with this. One, there might be some governing principle or law that determines how these sub-atomic particles move/act. Or two, even if they truly are random, that's still not freedom. Look at it this way, if you have to choose chocolate, vanilla, both, or none, and you have to roll a die to decide, you don't get a choice in the matter. You have to randomly choose every time you make a decision, therefore you really don't have any choice in the matter. So either way, regardless if the universe is deterministic or indeterministic there's no way to have free choice (we'll go more into that later, but that's the way it's looking so far).
Don't worry, I'm not trying to say there's no such thing as free will or freedom of choice. The problems (at least to some extent) stem from the logical link between the universe being deterministic and that relation to free will. The logic seems to say that if every instant of the universe is somehow determined by the previous instant, then there's no such thing as free will. And, as I've said even if it's not determined by the previous instant, that's not truly free will either. How can we reconcile this issue? I'll give you a hint, I don't think there will be a resolution. Prof McGinn doesn't seem to think there will ever be a resolution either.
Some seem to think that free will is somehow compatible with determinism. I don't see how that can be but I can see that one has to draw a line somewhere. Let's try to come at this from a different angle. Let's continue to use the chocolate/vanilla decision, starting at the end and working backwards. The very last instant is your hand picking up whatever ice cream cone you choose. In the instant immediately preceding that a signal went from your brain to your arm/hand to reach out and take whatever you've decided. Is that a decision in itself? I don't think anyone would say that it is; though it stands to reason that the brain can still be indecisive and change and choose a different option even after the signal has been sent to the arm/hand to pick up the ice cream. You could even touch one of the cones and then change your mind and pick something different. Then, just before the signal is sent from the brain to the hand, there's processing in your mind. Maybe you're weighing the options... Chocolate, yum, vanilla, yum, both? I'll get fat. Neither? But I really want ice cream. When I was talking to my wife about this her answer was hilarious, "stop thinking and just take both." So we're somewhere in the brain making the decision now. Determinism would say that you're genetically predisposed or raised to make whatever decision you do end up choosing. But wait, can't you go against that? Especially now that you've (hopefully) considered all these determining factors? You know you've got a terrible sweet tooth, but you're trying to cut back so you decide none. Or, your parents liked to reward you with chocolate sweets for good behavior when you were young, but you know that so you decide to go against the grain and pick vanilla. So, where did the original decision come from? Is it from the person who set the ice cream in from of you? Maybe that was the inciting incident, but that certainly isn't a determining factor or a decision in itself.
The next lecture is going to cover more of this intractable issue when it comes to the mind-body problem. But here's the question, where do thoughts, in general, come from? I'm not talking about observations of things within the world, that's mostly self-explanatory. I'm talking about just thoughts in general.
One important point Prof McGinn says in the lecture that I disagree with on the same grounds I disagreed with him on skepticism and epistemological ignorance. He says that we cannot just flippantly dismiss the notion that we don't have free will. I say, why not? Let me put it to you this way, if we all understand that there exists such notions as free will and praise and blame for actions but we cannot ever follow the rabbit hole all the way down will that change the way we behave? Not for me. I believe God gave us free will as incomprehensible as that can be at times I believe God set up the universe with laws and logic and that we fit into that design in an important way, but that we have the free choice to ignore that plan and attempt to go our own way. There's another thing I'd like to point out... This concept of determinism is determined (pun intended) by the ability to do things that only God could do anyways. Things like freeze time and look at one instant, neurons fire so fast it's measured in milliseconds and multiple neurons fire at once, so to be able to see the deterministic characteristics in the human brain, would take a much more accurate accounting of the brain than we have (or every will have, to my estimation). Then there's a universality to it, one would have to have the power to read genetic code and understand genetic predisposition as well as a thorough understanding of the decider's history of how he/she was raised. Only God could have such abilities so I would say we need not trouble ourselves (too much) over not being able to completely understand these things. I would say, we don't know, and we never will so don't get too bent out of shape about not knowing. Keep calm and eat ice cream.