I'd like to better understand some concepts from Aristotle's Metaphysics. I'd like to know what does he mean by a "substance" (Ousia), does he just mean anything that exists? Can any substance be "explained" by Four Causes? For example, does a seed (of a fruit) answer all four causes? Well, it has a matter, it's effective cause would be (from what I understand) soil, water, warmth... And it's final cause would be a tree? But I'm having trouble grasping what would the formal cause of a seed be?

I'd also like to know how are the Four Causes and Aristotle's principles of "Potentiality and Actuality" connected? From what I gather, the "final cause" is just an actuality of a substance, while a "formal cause" has that potentiality?

For some context: At my university Philosophy is a mandatory course, and we only covered "Metaphysics" from Aristotle, so I might be missing out on some concepts he might have explained elsewhere (though I've tried googling). Please do answer my questions and / or point me to something a beginner can understand. Thanks!

1 Answer 1


Four Causes

Intrinsic causes:

  • Material: answers "Out of what (ex quo) is it?"
  • Formal: answers "What (quid) is it?"

Extrinsic causes:

  • Final: answers "Why or wherefore is it?"
  • Efficient: answers "Whereby is it?"

Adapted from this answer to the question "What if anything does Aristotle's formal cause actually explain?" (which in turn was adapted from this answer to the question "Is conception an Aristotelian efficient, or material cause?")

Four causes' relation to actuality & potentiality

Aristotle discovered the four causes in order to explain that motion is possible (contra Parmenides, who denied the possibility of change) and that, despite there being a plurality of beings in the universe, there are stable beings (contra Heraclitus, who thought everything is in constant flux).

Since the real distinction between actuality and potentiality is so important to Thomism, a good overview of Aristotle's solution to the Parmenides vs. Heraclitus controversy on change is given in Part II, "The doctrine of actuality and potentiality and its applications according to St. Thomas," of the free book The Essence & Topicality of Thomism.

Another good short work on this topic is Thomas Aquinas's On the Principles of Nature (De principiis naturæ).

From here, the first part of this work overviews the Aristotelian philosophy of nature:

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