Let's say that some being A is changed to being B (example: lion burned to ashes, cold metal turned to hot metal, etc.).

Thesis. It is impossible that being A is changed to being B.


  • Suppose that being A is changed to being B.
  • That means that the last moment of existence of being A is the first moment of the existence of being B.
  • But this gives us a contradiction, because in the last moment A is A, but also, because that moment is the first moment of existence of being B, A is also B, and that is impossible.


  • One may say that when A becomes B, that the last moment of existence of A is not the first moment of existence of B.But this also is impossible. The reason is that if those two moments do not coincide, then there is some time between them. From that would follow that what really happens is that A becomes non-being and that then from non-being B arises. But there would be no sufficient reason for why from non-being would then B arise and not some other being.

Question. What is wrong with the argument?

I am primarily interested in the response from the viewpoint of Aristotelian - Thomistic philosophy, but if someone has any good points to make he is welcome to answer. I was motivated to pose this argument by looking at Aquinas De Potentia Dei q.3.a.1.obj.10. However, I am unable to answer my question from his replay to objection.

Edit 1 (It would seem that admitting division of being in being in act and being in potency does not solve the problem.)

Let us say I admit division of being in potency and being in act. How does that resolve my problem? I can form my argument like this:

1) A is being in act and B is being in potency.

2) That means that there is a subject S which has (at least) two ways of existing (A and B) of which A is actual and B potential.

3) Let us say that S changes its way of existing, ie. it goes from A to B.

4) Either the last moment of actual A is the same as the first moment of actual B or it is not.

5) If it is, then the subject S is A in act and B in act; and that gives us a contradiction.

6) If it is not, then there exists some time in between during which S exists in pure potency or in some other actual way C.

7) But if S is pure potency, then S is not distinguished from non-being. In this case, the change to B is impossible because it would require that non-being becomes being.

8) But if S is not pure potency, but exists in some way, then we have a change from S existing in A actually to S existing in C actually (ie. transition from existing in A way to C way). But this does not solve a problem, but only pushes it back one step further, because now the question is: how we have change from A to C?

So it seems that admitting being in act, being in potency and matter which changes does not solve the problem (or at least I, unfortunately, do not see how it solves the problem). Also, it seems that the agent affecting the change is not relevant for the problem (or at least I do not see how he is); for even if I admit him, I do not see what changes in the argument.

  • 1
    Already known as Sorites Paradox. Jul 26, 2019 at 11:51
  • 1
    "the last moment of existence of being A is the first moment of the existence of being B" is very very similar to "the last hair before being bald". Jul 26, 2019 at 11:59
  • 1
    Consider also the so-called Paradox of countinuity : if change is a continuous process, you cannot find two separate but "adjacent" point in the process. If change is "quantized", you have the last moment of life followed by the first moment of Death. Jul 26, 2019 at 12:02
  • Why can't something be partly A and partly B?
    – E...
    Jul 26, 2019 at 16:21
  • Since we can clearly observe stuff turn into other stuff (ice melting, etc...) i think that would mostly be a proof that your concepts of "being" and/or "instant" are not operational.
    – armand
    Mar 21, 2021 at 10:30

3 Answers 3


The argument seems to be a variation of Parmenides's argument against change, especially the premise "ex nihilo nihil fit" that being ("B" in your example) cannot come from nothing (to which "A" was reduced):

  1. If a thing arrives at existence it comes either from being or from nothing.

  2. Now it cannot come from being (statue from existing statue). Still less can it come from nothing.

  3. Therefore all becoming is impossible.

Ex ente non fit ens, quia jam est ens, et ex nihilo nihil fit, ergo ipsum fieri est impossibile.
[Being is not from a being ∵ the being already is; nothing is made from nothing; ∴, becoming is impossible.]

The problem with your argument is that it neglects the reality of primary matter (ens in potentia, "potentially a being") and neglects the existence of the agent effecting the change.

  • Can you please explain how admitting those things (act, potency, matter,...) you mention solve my problem? See my edit of the question; it seems that even if we admit those things that the problem still remains.
    – Thom
    Jul 27, 2019 at 11:39
  • @Thom A is corrupted (loses its form = is reduced to primary matter), then the agent generates B (unites B's form with primary matter), bringing B into existence. Are you asking if there's a time when neither A nor B exist?
    – Geremia
    Jul 27, 2019 at 16:33
  • Yes, that is the part of the question. Also, what part of the argument in the edit you reject?
    – Thom
    Jul 27, 2019 at 17:26
  • @Thom I'm confused by your statement "2) That means that there is a subject S which has (at least) two ways of existing (A and B) of which A is actual and B potential." Is your S prime matter?
    – Geremia
    Jul 29, 2019 at 22:26
  • Imagine you have a piece of wood, and let us call that piece S. Now, S can exist as a chair (that is one way it can exist; call this way A), and it can exist as a bed (that is the second way; call this way B). Now imagine that S exists as a chair, ie. the way A is actual and way B is potential. So, in this example, S is not prime matter. But if I took substantial change as an example (lion to ashes), then S would be prime matter.
    – Thom
    Jul 29, 2019 at 22:34

I feel your argument works. It is one of the arguments used in the Perennial tradition to show the impossibility of change.

Change is seen to occur but the idea of change doesn't work when we assume the essential or fundamental reality of the changing object. So your argument is not actually against perceived change, which is simply a fact, but against the way we usually think of it.

Contrary to a comment above the argument against change is an argument for the oneness of Being. It takes us back to Parmenides and Zeno and the idea of an unchanging ground-of-being which encompasses all that changes but is itself beyond space-time and cannot change. For the 'non-dual' view change is not metaphysically real.

Our usual ideas of substance, change, time, space and existence are closely intertwined and they are all paradoxical. There is a solution but it requires adopting a very different notion of things and how they change.

If you study the 'problem of attributes'you'll see that at the heart of changing objects there is an emptiness that can never change.

You might be interested to read how change is explained by Nagarjuna and Middle Way Buddhism. The paradox you note does not arise. I'm afraid I don't have any particular links to post but there's lots of discussions online.

This relates to the issue of time. The physicists and mathematican Hermann Weyl argues for the unreal nature of time and any such argument will depend on the the unreality of change.

I'd say don't worry about your resolving your argument. It is one of many arguments against the reality of change. What needs resolving is the idea of time and change that gives rise to this paradox and many others. According to the Perennial or 'non-dual'philosophy we don't need to solve such paradoxes, just understand what they're trying to tell us about Reality.


change can be interpreted as a process of alternative creations and annihilations of a thing, assuming that change occurs in discrete durations (i.e change is quantized), by which let say a thing A (with a certain properties or accidents ) is created and endure the quantized duration of change, then it annihilates, and then a new thing is created, lets call it B (with a different properties added to or subtracted from the properties that thing A has before its annihilation ), by this process we guaranted the occurrence of change in things without rising any paradoxes (of motion or change ), and after that it doesn't make sense to ask how long the duration between a successive annihilation and creation, because there isn't any reference by which we can measure how much time has passed between a successive annihilation and creation, because the measure of time (i.e the duration that change take) is measured with respect to something changing (i.e reference) either internally or externally and that's because change is a relational phenomena, so we have no way to measure this duration without any change (internal or external) that can refer to this duration of time.

at how can something came out from nothing which is the the event of creation after the annihilation, i thing this question is a self-contradictory question, because nothing does not exist for something to came out from it, but rather the right formulation is, how can something came out not from a thing, and i don't think that this is an impossibility, but that's only if there is an external force that causes that something to exist but not from a previous thing.

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