What Did Aristotle Say About the Mind?

How does Aristotle define psychology? How far is the definition adopted by Aristotle from how psychology is defined today? This article will focus on those parts of Aristotle’s psychology which overlap with our modern conception of the discipline.

Certain issues to do with separating the mind from the body are discussed, after which the article focuses on Aristotle’s theory of perception. Having raised one problem with this theory, Aristotle’s conception of our faculty of understanding is then explored, and parallels with his theory of perception are raised. This article concludes with a discussion of the relationship between Aristotle’s psychology and his empiricism, and some parallels with the problems facing more modern empiricist philosophies.

What is psychology for Aristotle? It is worth stressing that what we call Aristotle’s psychology actually includes a far broader field of investigation than modern-day psychology. Psychology for Aristotle is, above all, the investigation of the soul (the mind is, in effect, a part of the soul), and the soul is not just an entity but also the principle by which all the processes of life are structured, meaning that there is no effective limit to what we can call psychological investigations in the Aristotelian scheme.

In short, psychology, on one definition, constitutes the study of life itself, of its organizing principles. This article is concerned not just with setting out Aristotle’s conception of the soul, but with those elements of Aristotle’s psychology that approximately correspond to a more modern conception of psychology. In other words, this article is concerned with what Aristotle has to say about the mind.

Beyond this, there is a tendency in Aristotle to vacillate on the question of if and how far the study of the mind and the soul is a proper subject of natural science. On the one hand, Aristotle thinks that the sentimental aspect of our mental lives is self-evidently bound up with certain physical processes — they are intractable from the rest of our body, which is a proper subject of inquiry for the natural sciences.

Yet at the same time, the intellect, our faculty of understanding, may well not be entirely like the rest of the body. Aristotle is genuinely torn as to how to treat our psychology, which methods are best applied to it, and so on. It is commonplace to observe that Aristotle’s own apparent indecision mirrors that which has come to define the study of the mind in philosophy.

The problem, simply put, is that attempts to separate the mind from the body seem to offer us incomplete descriptions; yet so too do those attempts to naturalize our mental lives — that is, treat them as though they were entirely a part of the body like any other.

This ambiguity is characteristic of Aristotle’s conception of the relationship between the mind and body. The element of the mind that Aristotle pays the most attention to is one which arguably has led much of the subsequent discussion of the relationship between mind and body: perception.

Perception is what distinguishes animals from plants: the most basic sense, which all animals possess, is touch. Most animals have access to at least some other senses as well. The standard interpretation of Aristotle’s theory of how perception actually comes about is summarized by the following quote from De Anima, Aristotle’s treatise on the soul: “perception comes about with [an organ’s] being changed and affected … for it seems to be a kind of alteration.”

For Aristotle, the essence of perception is firmly rooted in the change that one entity exerts on a composite. Part of the point of a theory of perception is to say not just how it works, but what perception is. Indeed, it is uncontroversial to suggest that what something is has a lot to do with how it works (or how the larger system or entity of which it is an element works).

One way in which subsequent philosophers have criticized Aristotle’s theory of perception hinges on his focus on the organ of perception rather than perception in itself. In other words, it hinges on his failure to properly explain what perception is, rather than just how it works. The question arises: what distinguishes the kind of alteration that a sense organ undergoes as a result of the effect of the stimulus upon it, versus that of some non-sensory organ, or indeed some other composite entity that can be altered by that same stimulus?

The answer to the question of what perception is seems rather obvious — when a sense-organ is altered, then perception results. When other organs or entities are altered, perception does not result. Well, quite — but what is perception then? We haven’t actually said what it is, but rather appear to have skirted around the question by saying what causes it.

Perhaps if perception was the kind of thing about which any possible confusion is trivial or unimportant, then this wouldn’t be such a problem. But, of course, there is a great deal of disagreement among philosophers concerning what constitutes perception. Perception cannot be limited to the five senses of touch, sight, taste, hearing, and smell, even in principle.

Some philosophers, like David Hume and John Locke, speak about our having inner perceptions — perceptions of or about our own minds. And such sub-categories of perception tend to overlap uncomfortably with the five senses. Describing perception necessarily requires clarifying further philosophical issues (what exactly is the difference between seeing an object and picturing it in our minds? what if we mistake an instance of the latter for one of the former?) To be clear, Aristotle’s theory of perception is not this straightforward, but it does certainly put the alteration of an organ at the very forefront of his conception of it.

On the Understanding and the Mind

Having addressed the perceptive element of the soul, what does Aristotle have to say about our faculty of understanding, or “mind” (nous)? For starters, describing nous as a faculty of understanding means adopting a conception of understanding in the broadest sense. That is, nous is our capacity to understand, but it is also our executive function (our capacity for deliberation and decision).

These two faces of the mind are clearly distinguished in Aristotle. He often speaks about our having two minds, namely, the theoretical mind and the practical mind. Though the distinction drawn between our faculties of perception and the faculty of nous is a harder one, Aristotle’s conception of intellection is strikingly similar to his conception of perception.

Christopher Shields, a modern philosopher whose summary of Aristotle’s psychology is the main source for this article, summarizes the parallel Aristotle draws in De Anima in the following way:

“Just as perception involves the reception of a sensible form by a suitably qualified sensory faculty, so thinking involves the reception of an intelligible form by a suitably qualified intellectual faculty.”

The thread running through both Aristotle’s theory of perception and his theory of nous is the idea that, in being altered, the relevant faculties become or become similar to the form of the object which affected them. How we should understand the distinction between an object and its form not only requires far more explanation than there is space for here, but is also a source of interpretative controversy among scholars. The distinction between thought and perception is sometimes framed by Aristotle as that between universals and particulars, but elsewhere that distinction is dissolved.

It would do well to conclude by discussing the relationship between Aristotle’s psychology and Aristotle’s empiricism. That is, the relationship between how he conceives of the mind and how he conceives of the way in which the mind comes to know.

Aristotle pre-empts John Locke, one of the first modern empiricist philosophers who famously described the mind as a blank slate, by claiming that the mind does not exist “in actuality before thinking.” The underlying thought behind both Locke’s and Aristotle’s conception of the mind is similar. If the content of the mind is the product of experience, then it follows naturally that the mind must remain supple and changeable enough to accommodate all of the various possible kinds of experience.

Contrast this with a more rationalist conception of knowledge and (therefore) the mind, which holds that what we come to know is, in some way, internal to the structure of our minds.

It is worth noting that this conception of mind gets Aristotle into problems that also pre-empt some of those faced by later empiricists. The relationship between this conception of the mind and its faculties, and that of perception and thought as involving those faculties being affected by a certain stimulus, appears a contradictory one.