Friday, February 17, 2006

Aristotelian causality

After Plato we get to the most elaborate treatment of causality in Ancient Greek thought - from Plato's student, Aristotle (384-322 BCE).

Aristotle famously distinguished four kinds of “cause”*: the material out of which things come; the form which things eventually have when they are perfected; that which brings about this completion, the efficient cause; and finally the purpose or function of such things, the final cause.

Being a quasi-empiricist, he opposed, even ridiculed, Plato's conception of transcendent Essences. As far as he was concerned the invisible realm of Essences was merely a hypothesis that could never be verified. However, following Plato, he developed a doctrine of categories which he believed defined the essence of an object. He argued that these essences could be identified on the basis of inductive arguments based on the observation of the phenomenal realm and that the phenomenal realm, despite always being in flux, moves towards specific ends. In this sense the phenomenal realm demonstrates a certain telos and as such physical matter is ordered according to its telos and substance. In other words, matter does not have the potential to become just anything but is ordered according to what it can, will and should become.

So while Plato contrasted the inherent structure of Essences with the flux of all phenomenal things, Aristotle taught that, from a condition of potentiality, each phenomenal thing necessarily strives toward achievement of a full reality in which its inherent essence is actualised. Thus, according to Aristotle, the phenomenal realm itself contains an inherent structure which allows observation from which logical principles can be deduced and induced. Enter science.

So the inherent potentiality and subsequent actuality of phenonema become the key characteristics of an Aristotelian notion of causality and the regularity of nature. To return to an example used in an earlier post, the phenomena of ice becoming water when heated is explained in Aristotelian terms as the actualisation of ice's potential to become water. The heat is the efficient cause of this change in state but unlike Platonic causality there is no fundamental transition from "iceness" to "waterness" because the "waterness" was already the potency of the block of ice itself. However, like Plato, Aristotle maintains that the cause of change must be assumed as an absolute necessity. Everything which undergoes change is made to do so necessarily by something. What undergoes change is what has a potency or capacity to do so and this actualization of mere potency, by definition, requires an actual agent; nothing which just has a capacity to undergo change can bring about that change by itself**. However, unlike Plato, the efficient cause is normally another phenomenal object, and not a transcendental Essence.

Finally, it's not completely clear to me what place necessity has in Aristotle's conception of causality. Given the identification of an effect on something with its inherent potency, then with any given efficient cause one can assume a necessary effect. Also, Aristotle's definition of knowledge makes use of a necessity condition by which that which is deemed knowledge is knowledge of that which necessarily holds in all cases. However, Aristotle's use of the inductive technique, and use of phrases such as "for the most part" when talking about the validity of the conclusions of deductive statements, seems at odds with a concept of unwavering necessity. For the moment at least, it seems to me with my limited reading that, with Aristotle, necessity became entangled with scientific generalisations as a mode of explanation and had left the domain of Ananke behind.

* The Greek word is aition which it seems is just whatever one can cite in answer to a “why?” question. So an aition is best thought of as an explanation or an explanatory factor. This understanding of "cause" is just what Nāgārjuna seems to mean by condition, yet Aristotle's exposition of causality doesn't seem to have entirely followed through in this rather pragmatic vein.

** This brings about an infinite regress which Aristotle "solves" by positing an "Uncaused Cause" which was later seen, by the likes of Aquinas, as another name for God. This infinfite regress, and the avoidance of Aristotelian-type solutions, is important to understanding Nāgārjuna's rejection of inherent causality.

No comments: