Alexander Pruss's Blog

• Dry eternity 2023-09-21
  Koons and I have used causal paradoxes of infinity, such as Grim Reapers, to argue against infinite causal chains, and hence against an infinite causally-interconnected past. A couple of times people have asked me what I think of Alex Malpass’s Dry Eternity paradox, which is supposed to show that similar problems arise if you have […]
• The infinite future problem for causal accounts of metaphysical possibility 2023-09-21
  Starting with my dissertation, I’ve defended an account of metaphysical possibility on which it is nothing other than causal possibility. I would try to define this as follows: p is possible0 iff p is actually true p is possiblen + 1 iff things have the causal power to make it be that p is possiblen. p is […]
• A dilemma for best-systems accounts of laws 2023-09-20
  Here is a dilemma for best-systems accounts of laws. Either: law-based scientific explanations invoke the lawlike generalization itself as part of the explanation, or they invoke the further fact that this generalization is a law. Thus, if it is a law that all electrons are charged, and Bob is an electron, on (1) we explain […]
• Gratuitous and objective evil 2023-09-20
  Suppose, highly controversially, that no defensible atheist account of objective value is possible. Now consider a paradigmatic apparently gratuitous horrendous evil E—say, one of the really awful things done to children described by Ivan in the Brothers Karamazov. The following two claims are both intuitive: E is gratuitous E is objectively evil. But if there […]
• The evidential force of there being at least one gratuitous evil is low 2023-09-19
  Suppose we keep fixed in our epistemic background K general facts about human life and the breadth and depth of evil in the world, and consider the impact on theism of the additional piece of evidence that at least one of the evils is apparently gratuitous—i.e., one such that has resisted finding a theodicy despite […]
• Hiddenness and evil 2023-09-19
  There is some discussion in the literature whether the problem of hiddenness is a species of the problem of evil. I think the theist should say that it is, and can even identify the type of evil it is. There are some important propositions which it is normal for a human being to know, or […]
• Ontology and duck typing 2023-09-14
  Some computer languages (notably Python) favor duck-typing: instead of relying on checking whether an object officially falls under a type like duck, one checks whether it quacks, i.e., whether it has the capabilities of a duck object. You can have a dog object that behaves like a vector, and a vector object that behaves like […]
• On two problems for non-Humean accounts of laws 2023-09-13
  There are three main views of laws: Humeanism: Laws are a summing up of the most important patterns in the arrangement of things in spacetime. Nomism: Laws are necessary relations between universals. Powerism: Laws are grounded in the essential powers of things. The deficiencies of Humeanism are well known. There are also deficiencies in nomism […]
• Ontology as a contingent science 2023-09-12
  Consider major dividing lines in ontology, such as between trope theory and Platonism. Assume theism. Then all possibilities for everything other than God are grounded in God. If God is ontologically like us, and in particular not simple, then it is reasonable to think that the correct ontological theory is necessarily determined by God’s nature. […]
• Reverse valve masking 2023-09-07
  I was exposed to Covid recently, so by University rules I need to mask for a while. I don't particularly love masking at the gym, but I found a nice solution. My go-to mask for physical activity during the pandemic was the Trend Air Stealth N100 respirator, with the valve replaced by a 3D-printed blocker. […]
• On the plurality of bestnesses 2023-09-06
  According to the best-systems account of laws (BSA), the fundamental laws of nature are the axioms of the system that are true and optimize a balance of informativeness and brevity in a perfectly natural language (i.e., the language cuts reality perfectly at the joints). There are some complications in probabilistic cases, but those will only […]
• On probabilistic best-systems accounts, laws aren't propositions 2023-09-06
  According to the probabilistic best-systems account of laws (PBSA), the fundamental laws of nature are the axioms of the system that optimizes a balance of probabilistic fit to reality, informativeness, and brevity in a perfectly natural language. But here is a tricky little thing. Probabilistic laws include statements about chances, such as that an event […]
• Where are we? 2023-09-01
  Unless something like the Bohmian interpretation or a spatial collapse theory is right, quantum mechanics gives us good reason to think that the position wavefunction of all our particles is spread across pretty much all of the observable universe. Of course, except in the close vicinity of what we pre-theoretically call “our body”, the wavefunction […]
• Substantivalism and locality 2023-08-31
  I find myself going back and forth between substantivalism and relationalism about spacetime. On a substantivalist theory, the points of spacetime are real. But here is a problem. It seems essential to the concept of a point that geometric relations between points are essential to them. If two points are a certain distance apart, say, […]
• An Aristotelian argument for presentism 2023-08-30
  Here is a valid argument: Matter survives substantial change. It is not possible that there exist two substances of the same species with the very same matter. If matter survives substantial change, it is possible to have two substances of the same species existing at different times with the very same matter. So, it is […]
• Matter and distinctness of substance 2023-08-29
  According to Aristotelianism, the distinctness of two items of the same species is grounded in the distinctness of their matter. This had better be initial matter, since an item might change all of its matter as it grows. But now imagine a seed A which grows into a tree. That tree in time produces a […]
• Are we finite? 2023-08-28
  Here’s a valid argument with plausible premises: A finite being has finite value. Any being with finite value may be permissibly sacrificed for a sufficiently large finite benefit. It is wrong to sacrifice a human for any finite benefit. So, a human has infinite value. (2 and 3) So, a human is an infinite being. […]
• A sharp world 2023-08-24
  Here are one way of believing in a totally sharp world: Epistemicism: All meaningful sentences have a definite truth value, but sometimes it’s not accessible to us. This has the implausible consequence that there is a fact of the matter whether, say, four rocks can make a heap, or about exactly how much money one […]
• The Alpha and the Omega 2023-08-23
  For a long time I have thought that the identification of God as the Alpha and the Omega in the Book of Revelation is very Aristotelian: God is the efficient and final cause of all. Indeed, Revelation 22:13 explicitly glosses as he arche kai ho telos. This may initially seem an over-metaphysicalization of Scripture, but […]
• Substances and their existences 2023-08-22
  I used to think that: x is a substance just in case   is not grounded in any fact about any other entity other than x. But it is plausible that a finite creature’s existing is its being created. And that Alice is created seems to be grounded in God creating Alice, which seems to […]