Bonald had a provocative post (well, to the extent that intramural philosophical debates over realism can be provocative) at The Orthosphere, where he argued that Plato was ‘right’ and Aristotle ‘wrong’ on the fundamental question of universals. I left a comment there with some scattered thoughts the post prompted, this post is a reworked version of that comment.
Universals
On the question of universals, I think Bonald is correct that for the form in a concrete substance such as a dog to be the same as a form in my mind when I entertain the concept dog, there has to be some overarching form of dogness independent of both the concrete dog and my mind to which they both relate. A related problem I see with the pure Aristotelean position is one of causality: if there is no independent Form of Dogness, what causes the dog’s form to exist in concrete entity in the first place? The Platonist can appeal to the transcendent Form of Dogness as an exemplary or formal cause in which the individual dog participates. The pure Platonist position, meanwhile, suffers from these archetypal Forms simply being free-floating, i.e., ‘where’ does the Realm of the Forms exist? (In one sense, this question is malformed: the Forms, not being concrete entities, do not exist in a spatial location; however, what the question is really getting at is from whence do these plurality of transcendent Forms derive? Do they just exist, or do they have a source?).
The Neoplatonic synthesis, and later, the Aristotelian-flavored ‘scholastic realist’ position favored by Edward Feser, harmonized these two accounts and avoided the problems of either: it accepted Plato’s doctrine that the Realm of the Forms exists, allowing a common reference point for the form I entertain in my mind and the form existing in a concrete entity, but these Forms exist as eternal Divine Ideas in the Divine Mind, preserving Aristotle’s insight that form cannot exist independently, but must exist in a mind if not in a concrete substance.
The Soul
The Platonically inspired conception of the soul seems prima facie to harmonize well with Christianity, since it follows pretty straightforwardly from Platonism that the soul is immortal. However, it is harder to reconcile with the Christian doctrine of the bodily Resurrection, since the Platonist tendency is to view the body as inessential to the person and as a prison to escape. The Aristotelian conception of the soul is famously that the soul is the form of the body: it conceives of the soul and body as having a much more intimate relationship, as both being constituents of a single substance, analogous to the way that the spherical shape of a basketball and the rubber material of which it is made do not constitute two separate things, but are two aspects of the same single thing (that cannot be ‘separated’ without destroying the basketball). I find this view much more congenial: both because it accords with experience of the body as being truly an intimate part of me, rather than as something alien impeding my true nature and from which to escape, and because it is more consistent with the resurrection: if our bodies are truly part of us, then to exist in the next life sans body would be a sort of incomplete and deficient existence. I also find Aristotle’s teachings on the different types of souls – vegetative, animal, rational – an elegant elaboration on the soul as the principle of life.
The challenge with the Aristotelian conception of the soul is, of course, how does it survive death? In the general case, when the form and matter of a substance separate, the form ceases to exist (and the matter takes on a new form), since form is not a substance in its own right and therefore cannot exist independently. So, if the soul is the form of the body, how does the soul continue in existence after death, but prior to the resurrection?
Here is where I think the Thomistic development of the basic Aristotelean doctrine was a key advance. Because the rational soul has an immaterial part that does not depend on matter for its operation (though it does depend on matter for its ordinary functioning since it needs inputs from our sense organs), this part can subsist on its own after death of the body. Nonetheless, the human person existing in such a state is radically diminished: Feser likens it to a ‘full-body amputation’. One happy feature of this solution then is that it concludes to human immortality without sacrificing the notion that our bodies are required for a complete and flourishing existence. While the immortality of the soul may not follow as obviously from Aristotle’s doctrine as it does from Plato’s, I find the Thomistic argument (not spelled out here) to be plausible and not ad hoc as some claim.
Knowledge
Another topic on which Plato and Aristotle differed was on knowledge, i.e., how we come to learn things. Plato puzzled over the paradox of how we gain new knowledge and devised his theory of recollection, the idea being that we pre-existed our births with this knowledge already in us, and so that when we ‘learn’, we are tapping into this already innate knowledge. (At one time in my life, I flirted with the idea of the pre-existence of souls – until I learned that this contradicted Christian doctrine – but more as a solution to how we all participate in Adam’s original sin than as a solution to the paradox of knowledge).
Aristotle’s view of knowledge is that all knowledge is first in the senses: in other words, we gain new knowledge by observing empirical reality from the world around us. The human mind is capable of abstracting intelligible forms from the sensible world, which allows us to go beyond the mere sensible and particular and ascend to knowledge of universals.
Needless to say, the Aristotelian view today is more attractive to most, and it has the benefit that it acknowledges what seems to be true from experience: that we gain knowledge by observing the world. A challenge Aristotelian epistemology faces, however, is how do we learn of truths that are not or even cannot be instantiated in the physical world: for example, how do we learn certain mathematical truths about infinities when an actual infinity cannot be instantiated in the world, or about multi-dimensional vector spaces that go beyond the three dimensions of our experience? James Franklin, a philosopher of mathematics who takes an Aristotelean approach to the subject, addresses these concerns in some of his work, so I may return to that topic in a future post.
An intriguing theory of knowledge more Platonic in spirit is the ‘Illuminationist’ theory, represented by St. Augustine and St. Bonaventure. The idea is that divine illumination is required to achieve even ‘natural’ knowledge of eternal and necessary truths: how can a finite, contingent, and time-bound mind grasp truths that are infinite, eternal, and necessary, such as mathematical truths? It must receive aid from something that is itself infinite, eternal, and necessary. We know things by the divine exemplars, which illuminate, as it were, the things known, though we do not directly see the exemplars themselves (until granted the beatific vision). These exemplars act as the standard by which the things known are compared. However, sensation is also required: we need to have experienced an actual existing dog in order to know and compare with the standard. Just as we require light to see a material object with our eyes, our minds require divine illumination by which to apprehend eternal truths. (Here’s Feser’s post on Augustine on divine illumination).
Averroism and Nominalism
Bonald makes the provocative suggestions that pure Aristotelianism has a fundamental tendency toward Averroism and has difficulty avoiding nominalism, Averroism having become quite popular in the Latin West soon after Aristotle was rediscovered in the 13th century (though mediated to a large degree by Averroes’s commentaries), and nominalism having eclipsed realism a mere century later.
But what about Islam? Aristotle had been central to Islamic philosophy for significantly longer than it had in the Latin West—since probably at least the 9th century with al-Kindi—and no one made the inferences Averroes did until, well… Averroes in the 12th century. As far as nominalism goes, the very influential Ash’arite school was voluntarist and occasionalist (and perhaps also nominalist?), but as far as I know they did not derive any of this from Aristotle. Indeed, they were opposed to Avicenna, who remains the greatest Muslim philosopher and who was an Aristotelian and realist.
And then what about philosophy in the Byzantine empire? They never lost Aristotle’s works, which remained actively studied and commented upon, but did they suffer from a tendency toward nominalism or Averroism? I’m not aware that they did. Indeed, Aquinas—a realist and anti-Averroist—received a warm reception in the 14th century in the East by many because they were impressed with the high quality of his interpretation of Aristotle, which seemed to surpass their own despite his not being Greek.
As for Platonism, it seems that it too has doctrines that can easily develop in harmful directions: Gnosticism appeared almost immediately after Platonism became the dominant philosophical outlook of the Roman Empire in the first century, and there also seems to have been a tendency even among non-Gnostic Platonists to regard matter as evil (e.g., Plotinus).
Bonald, in response, suggested that the medieval Aristotelianism of say, Aquinas or Scotus, may have avoided the Averroist tendency by incorporating Neoplatonist elements. This is an interesting suggestion because it would also be consistent as an explanation of how the Islamic tradition avoided Averroism for as long as it did: the philosophical tradition of al-Kindi, al-Farabi, and Avicenna was a blending of Aristotelianism with a healthy dose of Neoplatonism (the Enneads were one of the major source inspirations for Islamic philosophy), though with the former being the dominant partner. Meanwhile, Neoplatonism, the major philosophical influence on the church fathers and early medieval tradition, was itself already something of a synthesis of Platonism and Aristotelianism, but with the former as the dominant partner. Likewise, the Byzantines could count both Aristotle and Plato as major influences on their thought (I will note that it was the Neoplatonist Gemistos Plethon who attempted a revival of paganism in the East).
So, perhaps the lesson is that Plato and Aristotle both need each to help temper the other’s tendencies toward extremes when left unmoderated.