Capaldi PhD Columbia, Smit PhD Catholic Univ. of Leuven. The Art of Deception (2007). p. 191-2.

According to Aristotle, the concept of "causation" has to be understood in four different senses.

They continue with my emphasis in bold below:

The material cause is that out of which something is made or constructed; the formal cause refers to its internal structure; the efficient cause is that external agency from which the thing comes or originates; the final cause is the goal, function. or pur- pose of a thing.

When Aristotle applied this understanding of the four causes to man-made objects his analysis went as follows. A table, for example, is made of wood (material cause); it has the shape or form of a series of rectangles (formal cause); it was produced by a carpenter (efficient cause); and its purpose is to serve as a surface for such activities as eating and writing (final cause). The same analysis can be applied to natural objects. For example, in the case of an acorn, its material cause is the organic substances that compose it; its efficient cause is an oak tree, namely, the parent oak tree; its formal cause is its structural potential to become an oak tree; and the final cause is to become another oak tree.

  1. Please see the titled question.

  2. Why isn't an acorn's Formal Cause rather its physical shape, as photographed beneath?

enter image description here

2 Answers 2


I don’t think the Capaldi and Smit book is consistent in examining the formal cause. Their definition is, “the formal cause refers to [an object’s] internal structure“. Their example is, “[the wood] has the shape or form of a series of rectangles “. These two statements do not necessarily mesh with each other.


The question is Why's an acorn's Formal Cause "structural potential to become an oak tree" rather than its physical shape?

Capaldi and Smit write that "the formal cause refers to its internal structure". Giving them the benefit of the doubt, "internal structure" may include the seed's shape and is a way to describe what an acorn is.

To try to get other information about the idea of a formal cause, consider how Andrea Falcon describes the four causes as "four types of things that can be given in answer to a why-question":

  • The material cause: “that out of which”, e.g., the bronze of a statue.
  • The formal cause: “the form”, “the account of what-it-is-to-be”, e.g., the shape of a statue.
  • The efficient cause: “the primary source of the change or rest”, e.g., the artisan, the art of bronze-casting the statue, the man who gives advice, the father of the child.
  • The final cause: “the end, that for the sake of which a thing is done”, e.g., health is the end of walking, losing weight, purging, drugs, and surgical tools.

Although Falcon also refers to a formal cause as a "shape", it is more generally described as an "account" of what something is. In the case of a seed, one can imagine that its formal cause could be the "structural potential to become an oak tree".

Finally, let's consider how Aristotle describes these four causes. Here is Hugh Tredennick's translation of Metaphysics, V. II. 1-3:

enter image description here

Aristotle decribes the formal cause as a "pattern" or "essential formula". Note that for Aristotle it does not have to be a "shape". It could even be "the ratio 2 1 and number in general is the cause of the octave--and the parts of the formula".

The formal cause may be more than the physical shape of the acorn. The "structural potential" of the acorn does describe what this seed is: it is something that could become an oak tree which would be its final cause.


Aristotle, Metaphysics, translator Hugh Tredennick 1933 (Internet Archive: https://ia801602.us.archive.org/11/items/in.ernet.dli.2015.185284/2015.185284.Aristotle-The-Metaphysics.pdf)

Capaldi, N., Smit, M. (2007). The art of deception: an introduction to critical thinking. Prometheus Books.

Falcon, Andrea, "Aristotle on Causality", The Stanford Encyclopedia of Philosophy (Spring 2015 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/spr2015/entries/aristotle-causality/.

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