What are "generation and corruption" in Aristotle's philosophy?

Question

In discussion of Aristotle's natural philosophy, the concept of "generation and corruption" is often invoked. It's the translated of one of his books' title (On Generation and Corruption). Today in everyday's use the words "generation" and "corruption" are quite generic, but when talking about Aristotle's physics it seems that they refer to specific concept(s).

What do they mean and how do they help the study of nature? To my mind, matters don't actually get "generated" or "corrupted" in everyday events, they just change. For example, water becomes ice, hydrocarbon + oxygen become carbon dioxide + water, and so on. But that's me, who, unlike Aristotle, studied modern physics and chemistry. In Aristotle's day, what were generation and corruption and how did they explain natural phenomena?

Answer 1

Here is how St. Thomas Aquinas, in his De principiis naturæ §§6-7, explains generation and corruption:

6. Because generation is a motion to form, there is a twofold generation corresponding to this twofold form. Generation simpliciter ["simply"] corresponds to the substantial form and generation secundum quid ["according to something"] corresponds to the accidental form. When a substantial form is introduced we say that something comes into being simpliciter, for example we say that man comes into being or man is generated [something]. But when an accidental form is introduced, we do not say that something comes into being simpliciter, but that it comes into being as this; for example when man comes into being as white, we do not say simpliciter that man comes into being or is generated, but that he comes into being or is generated as white [somehow].

7. There is a twofold corruption [corruptio] opposed to this twofold generation: simpliciter and secundum quid. Generation and corruption simpliciter are only in the genus of substance, but generation and corruption secundum quid are in all the other genera. Also, because generation is a change from non-existence to existence, contrarily, corruption should be from existence to non-existence. However, generation does not take place from just any non-being, but from the non-being which is being in potency; for example a statue comes to be from bronze which is a statue in potency and not in act.

Answer 2

As I understand it, in Aristotle's context:

• "generation" means "creation" (also in the sense of "composition"/"association")
• "corruption" means "destruction" (also "decomposition"/"dissociation")

The overall issue where these terms play a central role is that of the nature of the observable world -- what are things made of and how do they come into being.

One of the principal questions that Aristotle addressed was whether the process of "generation" of new objects (accompanied by destruction/"corruption" of old objects) is something different from the process of "alteration", in which old objects undergo change to become new objects.

Aristotle identified one group of Greek philosophers (those who thought that there was a single fundamental material "principle" of all things, e.g. Thales::water or Anaximenes::air) as compatible with the belief that "alteration" is the only possible way for entities to come into being, since (following the single-principle logic) all objects must be the different "alterations" of the same primary substance.

He identified another group (those who thought that there were multiple fundamental material "principles/elements", e.g. Empedocles::4 elements or Democritus::atoms) as compatible with the belief that "generation" is the primary mechanism of coming into being (and is different from "alteration"), since (following the multiple-principle logic) objects must be compositions of the multiple material principles/elements (that do not themselves change).

Aristotle based his own account of how objects ("substances") come-to-be on his conception of substances as "having" matter and form (which are two of his Four Causes).

1. A substance can come into being as the result of matter combining with form -- this is "substantial change" or "generation of a substance" (e.g. the matter "bronze" combining with form to become the new substance "bronze statue").
2. A substance can also come into being as the result of another substance changing its form -- this is "accidental change" or "alteration of a substance" (e.g. the substance "unmusical man" changes to become the substance "musical man").

It's not clear whether Aristotle's own account is entirely coherent, but that seems to be the basic idea.

Answer 3

I remember reading an explanation of Aristotle's eudaimonia, describing it as 'human flourishing' and locating it in his background as a student of plants and biology. If we look at his views on mind and body:

Aristotle shared Plato's view of multiple souls and further elaborated a hierarchical arrangement, corresponding to the distinctive functions of plants, animals, and people: a nutritive soul of growth and metabolism that all three share; a perceptive soul of pain, pleasure, and desire that only people and other animals share; and the faculty of reason that is unique to people only. In this view, a soul is the hylomorphic form of a viable organism, wherein each level of the hierarchy formally supervenes upon the substance of the preceding level. Thus, for Aristotle, all three souls perish when the living organism dies. https://en.m.wikipedia.org/wiki/Mind–body_dualism

It seems he viewed organisation as able to act causatively on material being, in generation of new organisation. And corruption then as a decay or diminishing of order.

I am surprised to see anyone doubting whether Aristotle's account is coherent, it prefigures modern views and makes a lot more sense than the views of Descartes.