My family and I are now living in South Bend, Indiana. We survived the move well enough, though unfortunately some of our furniture didn’t. (The movers wrecked the baby’s crib, broke all four of our floor lamps, and lost a box containing three of wall pictures. Next time we go U-Haul.)<\/p>\n
Anyway, my first blog post in a long time concerns Aquinas’ distinction between act and potency. More specifically, I’m concerned with Aquinas’ claim, central to the first two of his “Five Ways” of proving God’s existence, that<\/p>\n
(1) Whatever is moved is moved by something else.<\/p>\n
If this is right, then there can be no self-movers. In the Summa Contra Gentiles<\/span> Aquinas presents three arguments for (1). None of these strike me as particularly convincing, but I want to focus for a bit on the third argument, which appeals to the act\/potency distinction. Basically, Aquinas argues as follows:<\/p>\n (2) Nothing can be both in act and in potency in the same respect at the same time. While I accept the validity of this argument, I am doubtful of its soundness because I find it very hard to come up with interpretations of ‘act’ and ‘potency’ that make both (2) and (3) true.<\/p>\n My first thought was that ‘act’ means actuality<\/span> and ‘potency’ possibility<\/span>, such that for something to be in potency with respect to property F is for it to be possibly F. On that reading, however, premise (2) is false. Since actuality implies possibility, it is perfectly possible – indeed necessary – that if X is actually F at time T then X is possibly F at time T.<\/p>\n My next thought was to make premise (2) true by defining ‘potency’ as possibly but not actually<\/span>. The problem is that now (3) is false. To see this imagine a hypothetical situation in which a self-mover M can move either to the left or to the right. Initially, M is in ‘potency’ (as we have defined it) with respect to both options. That is, both options are possible for M, but neither is at yet actual for M. Now suppose that M moves itself to the left. In that case, M ceases to be in ‘potency’ with respect to either option and is in ‘act’ with respect with to going to the left. All this seems perfectly consistent, which falsifies (3). Why? Because the shift from being in ‘potency’ w.r.t. going to the left and being in ‘act’ w.r.t. going to the left is diachronic<\/span>. M is never in ‘act’ and in ‘potency’ in the same respect at the same time<\/span>. This indicates that it is possible for the antecedent of (3) to be true while its consequent is false, which is sufficient to show that (3) is not a necessary truth.<\/p>\n My final thought was to interpret ‘act’ and ‘potency’ in a causal sense of active<\/span> and passive<\/span>, respectively. This plausibly renders (2) true, though the proponent of self-motion might object that it begs the question. But my main worry again is that (3) is false. Why can’t self-motion be understood in terms of acting at T1 so that M’s future self<\/span> is F at T2? Aquinas’ argument against self-motion only works if a self-mover would have to be both in ‘act’ and in ‘potency’ in the same respect at the same time<\/span>. But I just don’t see why the ‘act’ \/ ‘potency’ relation can’t be understood diachronically rather than synchronically. Indeed, shouldn’t the very act of self-motion shift the temporal index forward? If so, then (3) is false and with it falls one of Aquinas’ arguments in favor of (1).<\/p>\n","protected":false},"excerpt":{"rendered":" My family and I are now living in South Bend, Indiana. We survived the move well enough, though unfortunately some of our furniture didn’t. (The movers wrecked the baby’s crib, broke all four of our floor lamps, and lost a box containing three of wall pictures. Next time we go U-Haul.) Anyway, my first blog\u2026 Read More »<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-42","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/posts\/42","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/comments?post=42"}],"version-history":[{"count":0,"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/posts\/42\/revisions"}],"wp:attachment":[{"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/media?parent=42"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/categories?post=42"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/alanrhoda.net\/wordpress\/wp-json\/wp\/v2\/tags?post=42"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
(3) If there were a self-mover, then something would be both in act and in potency in the same respect at the same time.
Therefore,
(4) There cannot be a self-mover.
Therefore,
(1) Whatever is moved is moved by something else.<\/p>\n