This post contains three unconnected topics, so feel free read only the one that interests you most. The topics are: the casual closure of the physical universe, an objection to the formalization of descriptions, and evidence for god’s existence.
1: Casual Closure of the Physical Universe
First let me quote myself on this topic:
“Let me assert that the complete physical description of the universe is causally closed, by definition. Of course this isn’t true for our current physical description of the universe, as surely there are laws that haven’t been discovered yet. But, it is closed in principle because of how we decide what kind of information count as ‘physical’. For example let us pretend that the physical description wasn’t casually closed and that there was some non-physical force, Y, that had a causal effect on the physical world. If it has a causal effect then there is some physical system, X, that will produce result X-1 in the presence of Y and X-2 in the absence of Y. This behavior however is enough to postulate some physical cause, y, of X-1. A materialist could produce a detector for y using system X, and using this detector identify all of the ways in which Y had a causal effect on the world. This causal effect would be completely captured by y, which is part of the physical description. It is true that there may be more to Y than the physical properties captured by y. In this case we might argue that Y-y still exists and is non-physical. However Y-y has no casual effect on the world, and thus is epiphenomenal (because all the casual effects have been captured by the physical y).”
One possible objection to this argument is that it doesn’t exclude the lawless interaction of the non-physical with the physical. However consider what a lawless interaction means. It doesn’t mean simply that there is only a chance of a certain interaction happening. For example neutrinos interact only rarely interact with normal matter, but because their interaction is has a predictable probability we still consider them physical. A truly lawless interaction is one in which no information about the non-physical world could be deduced from its interactions with the physical. This excludes every proposed non-physical domain that I can think of. For example if you believe in god surely god acts rationally, and hence predictably. Likewise any possible interaction between a mental substance and the physical world must be lawful, since it is almost certain that every time I wish for my arm to rise it goes up. Additionally if the non-physical domain really is lawless how could we possibly know anything about it, since as I stated above no information about it can be derived from the effects we observe? Thus I still maintain that we can’t have any knowledge, or reason to believe in, non-physical objects.
2: Wittgenstein’s Objection
A few posts ago I made the assertion that we could have a predicate that holds true when a description applies and false when it doesn’t. However Wittgenstein argued, with his famous example of the word “game”, that the formalization I assume is in fact impossible. Although I think that Wittgenstein’s argument shows that it isn’t easy to come up with such a predicate, and that a universally acceptable one is impossible, it is easy to demonstrate, given the assumption of materialism, that it must be possible to construct such a predicate. For example consider a single person’s choice to call something a game or not. That choice is arrived at based on physical activity in their brains. Since such activity obeys mathematical laws we can develop an extremely complicated formula that represents this activity. This formula is the predicate we were after, assuming that we set the math up so that the input represents the activity in question and the output represents the person’s choice. Thus Wittgenstein was wrong.
3: Evidence For God’s Existence
Lately some of my posts have made me think about the idea of god. (see here and here) Let me assume that we are persuaded by my arguments, and believe that, although god may not necessarily exist, it should be possible to find evidence for or against his/her/its existence. Furthermore let us assume that god is omnipotent and perfectly good. If this is true what kind of universe would we expect to find? Intuitively we would expect to find the best possible universe, but it seems obvious that the universe we live in isn’t (although Leibniz would disagree). However, if the best possible universe was created instead of this one we wouldn’t exist, and some other people would. Isn’t our own existence worth something? In fact how could a benevolent god choose between universes, when to pick one would be to deny an infinite number of people their existence. Clearly such a god couldn’t, all possible universes would have to exist. And surprisingly this is just what the multiple worlds interpretation of quantum mechanics tells us. Of course multiple worlds theories aren’t proven yet, and even if they were they still wouldn’t be evidence for god’s existence, only a lack of contradictory against. Still, it is something interesting to think about.