The Aristotelian-Thomistic distinction of act-potency is, among other things, supposed to solve Parmenides' paradoxes of change. Since change requires something non-existent popping into existence ex nihilo (as far as I can tell, this is the case because Parmenides, Aristotelians, and Thomists, treat property-instances like things, so that even something losing one property and gaining another means that one property-instance ceased to exist or another property-instance came into existence), and something can't come from nothing, it follows that all change is impossible. The things that exist just are what they are and never change.

Aristotle (so I've read) posited potentiality as a middle-ground between being and nothing, so that change doesn't involve something coming from nothing, but instead, something-in-a-state-of-potentiality becoming actual. The coffee cup changes from being hot to being cold, because the coffee cup was actually-hot and potentially-cold, but then the potential-coldness-of-the-coffee-cup was actualized (and, I guess, the actual-heat-of-the-cup reverted back into potentiality? Or did it cease to exist?).

Does this lead to Meinong's jungle, or a kind of possibilism in metaphysics, where all possible things (including property-instances) have being ("subsist"), and only some become actual? For example, before I was born, I existed in a state of potentiality, but so did a billion other children my parents could have had if things had gone differently. I came into being because my potentiality was actualized, and the billion other potential children remained in a state of potentiality. (This gets really strange, when I think about the coffee cup above, and that the potential coldness of that particular contingent coffee cup is something that has eternally subsisted, or existed potentially...)

  • Are you asking if impossibilities can exist?
    – Geremia
    Commented Jan 14, 2020 at 22:57
  • @Geremia Let's leave aside impossible objects for the moment, and focus only on possible ones. Do all possible objects (the gazillion possible people, possible coffee cups, possible property instances of possible objects, and so on) exist in some sense, and exist right now in that sense, according to the theory of act-potency? I know they don't actually exist, but then creating different grades of existence is what possibilists and Meinongians do. I just wanted to check my understanding, and probably ask some follow-up questions, if this is the case. Commented Jan 14, 2020 at 23:15
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    No, because Aristotle's potentialism is much more selective and actionable than possibilism. Something really has to be in the "potential" of a being, an abstract possibility does not cut it. Felt makes this point in an interesting way in Impossible Worlds:"the anti-Parmenidean (Aristotelian) notion of potentiality, as an intrinsic character of the actual, has tended to be supplanted by possibilities (in the plural)..., purely formal and discrete patterns. The dynamism of potentiality has been exchanged for a dust of homeless forms."
    – Conifold
    Commented Jan 14, 2020 at 23:28
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    @Geremia I'd rather not rephrase what he means, especially since I am unsure what "imperfect actuality", as Aquinas uses it, means. But the implication is that some possibilities are real, and others are just nominal, and it takes a non-trivial study of nature to discover which is which, not a formal convention. Meinong, on the other hand, reifies everything in sight.
    – Conifold
    Commented Jan 15, 2020 at 0:19
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    I think you are right about affinity to modal dispositionalism, especially in treating modality as irreducible to actuality, as in possibilism. Things "could have been" different in a nominal sense (logically possible or some such), but that does not endow them with potential existence. Felt even doubts "it makes any sense to hypothesize other worlds in which metaphysical principles true for this world are violated", or that "there is room at all for a purely logical, metaphysically innocuous, way", because logic "must perforce follow the laws of thought which obtain in this world."
    – Conifold
    Commented Jan 15, 2020 at 9:04

1 Answer 1


No, the act-potency distinction does not lead to Meinong's jungle. Meinong's jungle is a result of positing possible objects as concrete entities that subsist in some way, whereas the act-potency distinction only posits them as abstract possibilities. Abstract possibilities cannot be said to "subsist" in the same way that concrete entities do, so they cannot lead to Meinong's jungle.

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