I am a bit confused as to how Aristotle accounts for change (accidental and substantial). I seem to understand the idea of a substance being the compound of material and form to some degree, but how this is supposed to account for change, I do not see. Let me give you an example which I'm taking from the opening paragraphs of the following link (https://plato.stanford.edu/entries/form-matter/) which talk about Socrates become a musical man. Here, it says that, "when Socrates learns to play the flute, he transitions from a state of being unmusical (the lack) to a state of musicality (the form)."

Formulating this in a "substance = matter + form" way of thinking, I write this as

  1. Unmusical Socrates = Socrates + unmusical
  2. Musical Socrates = Socrates + musical

So, it seems that the matter, Socrates, is what persists here, as the lack "unmusical" passes to the form "musical".

However, in the article, it states "...in an accidental change, the underlying thing is the substance which acquires a new accidental property."

Herein lies my confusion. According to the above sentence, it is the the SUBSTANCE which persists. This seems odd, for if the substance is the compound which is supposed to be changing, it should not be persisting.

Can somebody help me an armchair philosopher? Thanks!

  • My answer, now deleted but to which I stick, has provoked too many questions to be useful. You must work out Aristotle for yourself or with the aid of others. I regret my time in writing and your time in reading.
    – Geoffrey Thomas
    Dec 31, 2019 at 20:52
  • I am not sure why it was deleted. I very much enjoyed our exchange and your last comment, I believe, pointed me in the right direction.
    – Mark
    Dec 31, 2019 at 20:54
  • Okay, thanks, I'll restore. I deleted only because I didn't think I was helping. Glad to be reassured. Best - Geoff
    – Geoffrey Thomas
    Dec 31, 2019 at 21:09
  • Roughly, "substance = matter + essence", whereas "form=essence + accidence", so while the form changed the substance didn't.
    – Conifold
    Jan 1, 2020 at 0:38
  • @Conifold very interesting way of thinking about it, and an elegant solution to my question, thank you! Do you have any references where substance is discussed as the compound of matter and essence, rather than matter and form? Or, one in which this "essence" is discussed? Maybe essence is "substantial form", discussed here: en.wikipedia.org/wiki/… Then, we'd have substance=matter + form, where form = substantial form + accidental form ?
    – Mark
    Jan 1, 2020 at 14:40

1 Answer 1


For Aristotle, all change is change of or in a substance. Substances are what ultimately exist and are the fundamental bearers or subjects of change. If a substance undergoes change in its essential, defining properties, in the sense that it loses those properties, then it ceases to exist as that substance. If a human being is essentially (definably) a rational animal, then if Socrates is incinerated, he ceases to be an animal and he ceases to be rational. He persists as matter but no longer exists as a human being, a substance with the esssential properties of animality and rationality.

Short of such drastic change the substance that is Socrates can undergo changes which are matters of contingency (para tautua - other than what is usually the case) such as contracting a rare disease, or of the accidental (as when Socrates, no physician, heals someone by some unintended action which is no part of his activity as a philosopher (ou pepuke)) or by chance (tuche) as when Socrates is surprised to meet a friend in the market-place when neither had any such encounter in mind.


Dorothea Frede, 'Accidental Causes in Aristotle', Synthese, Vol. 92, No. 1, The Thought of Marjorie Grene (Jul., 1992), pp. 39-62.

  • Thank you for the answer. So, would you say that my "substance = matter + form" formulation is a bit off? It seems here that you also want keep Socrates as the substance. Then what is it that persists (the same before, and after) the change? It makes sense that it is the matter which makes up Socrates that persists, as your first example suggests (matter persists/remains unchanged). But changes in which matter persists are used to describe "substantial changes", or the coming into/passing out of existence of substances. To me, Socrates becoming musical also involve matter persisting.
    – Mark
    Dec 31, 2019 at 19:24
  • If the substance persists, then no change could have occurred.
    – Mark
    Dec 31, 2019 at 19:58
  • It is matter with form ('informed matter', so to say) that makes Socrates a human being = rational animal; and different matter with the same essential rational form that makes Alcibiades a different human being, a different token of the same type. There is nothing wrong with your assumptions. What persists before and after the change when Socrates becomes musical is the 'substantial' Socrates, the Socrates of form and matter who has undergone the contingent or accidental change of a philosopher's becoming musical. I appreciate your courteous attention to my answer. I hope it helps. Best - GLT
    – Geoffrey Thomas
    Dec 31, 2019 at 20:06
  • Mark (1) Thank you once again. If you permit me one more question: You write that it is the " 'substantial' Socrates" that persists before and after the change. Accidental change is described as the form changing, or going from a lack to a form. But if a substance is the compound of material and form, and form changes, then substance must also necessarily change, right? Hence, substance cannot persist in an accidental change.
    – Mark
    Dec 31, 2019 at 20:18
  • Mark (2) You wrote in your original answer: "If a substance undergoes change in its essential, defining properties, in the sense that it loses those properties, then it ceases to exist as that substance." But in your last answer, you suggest that substance is what persists. How can it be both?
    – Mark
    Dec 31, 2019 at 20:26

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