Analyzing Aquinas II: Aristotle's Legacy

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Resuming our series on Thomas Aquinas, we will now delve into his metaphysics.  You'll recall from a previous post that metaphysics is basically the study of the fundamental nature of reality, or first principles.  Metaphysics is critical for coherently piecing together all those seemingly independent beliefs that together constitute a worldview.  The metaphysics that one holds (usually subconsciously) will shape the way one views the entire world.  You'll also remember from the first post in this series that while some of Aquinas' proofs for the existence of God are elegant, clever and compelling when correctly understood, they are often dismissed as foolish because modern thinkers are so far removed from his metaphysics.  The purpose of this post is to familiarize the reader with some basic distinctions that were crucial to Aquinas' thinking, and explain the history behind them.  This will allow us to venture into the arguments themselves without feeling overwhelmed (or underwhelmed if you are an atheist).1

Act and Potency

The first important distinction is between what scholastic philosophers would call act and potency.  These ideas originated in Aristotle's Physics as a response to a long debate that had been going on between the Pre-Socratic philosophers.  The disagreement was over the idea of change-- is change in the world real, or is it an illusion?  If change is real, is everything in a constant state of flux?  Parmenides of Elea thought that there was no such thing as change at all; while we may believe things change based on our faulty sensory perception, everything is actually one and unchanging.  As part of his ontology, he believed that there were only two categories for "being": existence and non-existence.  In order for something to be changed, it must be changed by something else; but if the only candidate to change existence was non-existence, then change must be impossible because something cannot come from nothing.  According to a representation by Plato, Heraclitus of Ephesus held oppositely that everything was in a never-ending state of change and that any appearance of stability was simply not real.2

Aristotle, in opposition to both of these schools, argued that change is real, but not pervasive.  He agreed with Parmenides that something cannot come from nothing, but disagreed that nothing is the only possible source to cause change.  This brings us to the above mentioned distinction; every object that exists is composed of act and potency (or else it is pure act in a very unique case that will be discussed in the next post).  A match, for example, is actually long, thin and fibrous.  It is also potentially warm/hot, bright and smokey.  To an Aristotelian philosopher, what an object is potentially, is rooted in its nature or essence, and is the main source of change-- an object is able to change a certain way because its essence contains the inherent power or potentiality to do so.

However, potential is not alone sufficient to cause change, according to Aristotle.  Another body is also required for change to take place.  Going along with the above example, a match requires an external body to create friction in order for its potential heat, brightness and smokiness to be reduced to actuality.  If this were not so, there would be no reason for a match became lit when it was struck and not at some other point.


The next crucial distinction is one that comes from the Latin word hylemorphism, which was first used (you guessed it!) in Aristotle's Physics.  The term is a compound word, composed of "hyle," meaning "matter," and "morphe," meaning "form."  Aristotle believed that just as every physical entity is a mix of of act and potency, it is also composed of matter and form.  The genesis of this idea begins once again with our Pre-Socratic friends, represented by Parmenides and Heraclitus.  Remember that Parmenides thought change was impossible because he viewed everything that existed as one unity rather than different entities.  Heraclitus, on the other hand, held that change was continuous because there was no eternal standard with which to conform.  This issue, called The Problem of Universals, or The Problem of the One and the Many, is one that philosophers struggle with even today.  How can one make sense of the fact that each object of everyday life seems to have its own independent existence, and yet shares an essence with many other objects?  Angela's cat, Sprinkles, is a distinct animal with existence independent from other cats, yet it shares an essence-- which we might call cat-ness-- with all other cats in the world.  The silhouette of a prism on the cover of Pink Floyd's "Dark Side of the Moon" album is a specific instance of a triangle, and yet it shares its triangularity with every other three-sided polygon in the world.

Plato, prior to Aristotle, believed that this could be best explained by a realm of abstract entities, called Forms, which exist as standards which everyday objects imperfectly exemplify.  All triangles are similar because they are each imperfect instances of the perfect platonic form of "triangularity."  All cats are similar because they are each instances of the perfect platonic form of "cat-ness," etc.  Now, you may be scratching your head, thinking this whole thing sounds rather absurd.  A Platonic Heaven which houses abstract forms such as that of "triangularity," "cat-ness," or "the good?"  It's a little too bizarre for me, thank you very much (you might be thinking)!  Well, that's exactly what Aristotle thought, too.  He believed that while there must exist a way to reconcile "the one" and "the many," an independent realm of perfect abstract objects seemed too ad-hoc, and didn't jive well with either common sense or the world as he saw it.  So what was his solution?

As mentioned, Aristotle believed that each existing entity has both matter and form.  Form gives an object its essence which it shares with other objects (the One), while Matter gives an object independent existence (the Many).  Matter without form, under this view, is called Prime Matter, and does not exist in reality because it is pure potentiality, devoid of any actuality.  Unlike Plato, Aristotle held that form could have no existence independent of matter either.  While a form is irreducible to matter, it cannot exist apart from the matter that it shapes.  In this view, forms exist in the actual world as opposed to a separate Platonic realm.  The form of a triangle is "a three-sided polygon whose three angles sum to 180 degrees."  The form of a human is "a rational animal." And so on.

The Four Causes

When post-Enlightenment moderns, such as ourselves, thinks of causality, what usually comes to mind?  One billiard ball bumping into another and causing it to be displaced, perhaps?  How about a rock or brick being thrown and causing a glass window to shatter?  In each case, we could identify the cause (the first billiard ball or the brick) and the effect (the displacement of the second billiard ball, or the shattering of the glass window), but, according to Aristotle, we would only be partially correct.  One unfortunate result of the Enlightenment is the tendency toward reductionism-- of interest here is the way that Moderns have reduced general causality to mere efficient causality.  Under an Aristotelian metaphysics (and consequently, Thomistic metaphysics), for an event to be fully understood or explained, each of four different types of causes need to be accounted for.  The first two causes, a material cause and a formal cause, are based on the hylemorphism explained above:

Material Cause:  A material cause is (to quote Wikipedia) the nature of the raw material out of which an object is composed.  For example, the material cause of a match being lit is wood and a mix of potassium chlorate, glass and phosphorus.

Formal Cause:  A formal cause is the aspect of change determined by the form of the object which is moving or changing.  The formal cause of a match is that it is long, thin, wood-like, etc.

And a third cause is one that has already been mentioned, and we are all very familiar with:

Efficient Cause:  An efficient cause is equivalent to that which initiates change in the object that is changing.  The efficient cause of a match being lit is the friction created by striking it against the box.

The last of the four causes is also the most foreign to someone living in the twenty-first century.  Material and efficient causes are accepted by virtually everyone (either explicitly in the case of a philosopher or scientist, or implicitly otherwise).  Formal causes are much harder to accept, but include organization of matter and utility which are concepts with which we are at least familiar (it is also the only way to resolve the Problem of Universals without straying into complete nonsense, but that's a matter for another day).  Final Causes have been rejected for centuries, however, and are thus more difficult to wrap our minds around.

Final Cause:  A final cause is the purpose or goal directedness of an object.  The final cause of a match is to produce heat and light.

In pre-modern times, the purpose of science (I use the term loosely here, based on its original definition of an analytic and methodical approach to understand the world) was to understand the world better at a fundamental level.  However, beginning with the Enlightenment and the Scientific Revolution, the goal of science was recast: it became less concerned with understanding qua understanding, and more concerned with understanding nature as a means to controlling it.  As a result, the focus narrowed greatly to empirical parameters which could be mathematically quantified.  You can see how this pushed final causality, a fundamentally qualitative concept, straight out the window-- it's like a miner who sifts everything out of his pan except the gold for which he is looking.  Of course, the reasons for doing this were practical and methodological in nature, and very appropriate for the task at hand, but have had very significant and regrettable consequences.  Unfortunately this post has already become long, so a more detailed explanation of these consequences will have to wait for another day.  However, I will take to defending the idea of final causality in my next posts when I discuss Aquinas' Fifth Way.

1. Much of the information from this post was from Edward Feser's books Aquinas: A Beginners Guide and The Last Superstition.

2. This view of Heraclitus is a widely believed, but wrong, interpretation which was propagated by Plato. For more information, consider this lecture, especially starting at 7:50.
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