Also note that I'm using the term "materialism" loosely to mean that oneself is a part of a larger world rather than the whole. I'm aware of the incomplete and approximate nature of existing physics. Physics is yet another layer of "modeled apparent reality" nested inside materialism. I'm not counting on any specific physics model to predict all that I can observe in a materialist world. Such a theory of everything does not exist, at least not yet. But what we do have are models which make reasonably good predictions at some local abstraction level, some fuzzily bounded local region of materialist reality. These models need not be limited to physics. Phenomena that can be roughly modeled at higher levels do not need to be reduced to low-level physics to predict future observations with good enough precision (though it could probably be done, with great effort).
Now, to answer your question. As I understand it, you're asking whether something external in the material world caused me to move my hands to type these words.
I think that's an accurate description. But you would have to take this statement in context of the prior explanations for it to make sense in a metaphysically strict manner.
We could model this in a pretty rough high level way: I look at screen. I see article that says something about consciousness. It piques my interest so I click and read, then I talk in the comments.
And we could think about what else caused this specific event of me typing these words. There are countless causal chains, but I'll list a few:
- My understanding of language and the words used here can be traced back to every interaction I've had with other people and objects in the past. I was not born literate. Change any one of those interactions and I may be saying something slightly (or very) different right now.
- I need to eat food and drink water, or I would eventually be too weak to move my fingers to type. This comment would never happen if I'm starving.
- I see that you made a comment, so I'm responding. Your decision to comment was a part of the cause of me writing this comment. If you did not make that decision, it would be impossible for me to write this reply.
If I want to challenge physics and claim the future is something that's completely unpredictable and can only be determined by my mind or god/simulation, I could think or pray really hard about teleportion, and see if I can teleport or move really fast 1 meter forward in 10 milliseconds, surpassing the biochemical limits of my muscles and joints. I can't. The movement of things have predictable bounds regardless of whether this apparent movement of matter has metaphysical origins in mind/simulation/god/whatever, it can be predicted as if it's material. Of course, I feel like I'm making decisions. But my very concept of a decision refers to exactly some process in my mind that's always subject to apparent external influence, rather than just internal processing. This intuition is backed by the fact that other people can predict my behavior to some extent. Like you just implicitly did by assuming that if I were to respond to your comment, then I would answer your question using words in natural language you can read. You implicitly made some predictions about what will be transmitted over the wire, what I will input on my end, and what I am thinking about (the sort of mental activity which leads to muscle movements to input readable natural language text to respond to your comment). These are very rough predictions, but they're right nonetheless. Again, I don't know whether I'm truly a brain grounded in material reality in a strict metaphysical sense, but it doesn't really matter if all of my observations make it seem like I am.
I know with metaphysical certainty that you are bound by the workings of a materialist world, because I am defining certainty using my own consciousness, and you are a part of my materialist model. But hearing this from me is not enough for you to prove to yourself in a metaphysically strict sense that you are in a true material world, even if we're both in a true material world, because your definition of certainty is based on your own consciousness, and we do not share the same consciousness. If I were a figment of your imagination or an NPC in a simulation, I could behave the exact same way and say the same things to you. I would always appear to be a part of your materialist model at the "apparently real" rather than the "ultimately real" metaphysical layer, as you appear to me, regardless of our true metaphysical grounding. So I cannot show you ultimate causation. I can only point out the practical equivalence of apparent causation.