The Nature of Mind in Aristotle’s De Anima 3.4 and 3.5

In De Anima 3.4, Aristotle gives us an account of mind. In De Anima 3.5, Aristotle tells us that what he had been describing is not mind in general, but passive mind or nous. The word nous describes mind, thought, and thinking. Passive mind as nous can be thought of as something like the passive power of thought. The main purpose of De Anima 3.4 is to say that mind is not perception. The way that Aristotle argues this is to draw a distinction between mind and perception. He says perception is bodily while mind is not bodily. If mind were bodily, this would place limits on its potentiality. If everything is thinkable, then mind has to have an unlimited potentiality. If mind does have an unlimited potentiality then it cannot be involved in a body. There is a question of what is it about being mixed up with a body that places limits on potentiality? If we think about the analogy of sense organs, they need to have a certain range of potentiality. For example, if the eye is going to be able to see all the colors, it needs to be structured in a certain way. In particular, the transparent medium between you and the colors you are seeing need to be clear, that is the transparent media need to be themselves uncolored. If these media, the jelly in the eye or air around you, were colored, this would reduce the potentiality for your eyes to pick up on colors.

The problem with bodies is that they are already always something so they have actuality. If we are to imagine that the thinking faculty is, as Heraclitus says, fire, this thing would be great at thinking about hot things, but it would be limited in its ability to think about cold things. In particular, it would be unclear how this thing would be able to think about other kinds of matter. If the thinking faculty is fire, then it would be unable to in some sense become something else like water or ice. So, if mind is understood as a kind of body, we get limitations on its ability to become anything. We therefore have a kind of first premise or axiom in this discussion: everything that is is thinkable. This sounds something like the Parmenidean Thesis where there is a kind of unity between being and thought. That is, what it is to be and what it is to be thinkable are the same thing. There is also another premise: to think something is to become it.

Aristotle would say that to think something is to become it insofar as it is separable from matter. This principle comes from the idea that thinking is a way of being affected by what is thought. There is a general Aristotelian causal principle that if we have an agent and a patient, the agent is an agent in virtue of being F and the patient is a patient in virtue of being potentially F. The agent can affect the patient by making it also F. Any act of causal influence, in Aristotle's account, is a case of the patient becoming what the agent was already. Aristotle is assimilating thinking to that model. He is understanding the idea that to think something is to become it as a downstream of his thesis of causal influence. Aristotle is not understanding thinking in terms of an antecedently held causal theory that is at home in the natural world. In the Phaedo, Plato develops a causal theory which is essentially a mental one. Plato says that an adequate causal theory is going to be one in which the Forms are understood to cause the things in the world. For example, if something is hot it is because it has the Form of the Hot. Plato goes as far as to say that physical interaction is not a part of causality at all. For Plato, all causation is a kind of imposition of an intellectual or ideal object on the world. It is not as if the theory that Aristotle is working with has its home in the physical. The theory began, in some sense, as a theory about the relationship between an intellectual object and a natural object.

These two principles or theses that Aristotle is working with can be taken as axioms in the context of De Anima 3.4 and they are the basis of the claim that mind has to be non-bodily. There is still, however, a question about what it means for mind to be non-bodily. The answer that Aristotle comes to is that mind is identical to what it thinks insofar as these things have no matter. That is, mind is identical to things that either have no matter in their own nature or it is identical to things insofar as they are somehow separable from matter. However, it would appear that what we get from the claim that what we think is just the activity of each thing, is that the activity of mind is not bodily. The activity of mind is not bodily because the activity of mind is in relation to non-bodily things. If to think is to become something then insofar as it becomes those things, it's non-bodily. The things that mind thinks are just the activities. This leaves unclear whether or not passive mind or nous is itself something that has no organ or is non-bodily or is not associated with any part of the body. What is clear is that the activity of mind is not bodily. This is as opposed to something like the activity of the sense organs which is bodily. The activity of the eye, when it sees the color red, is in a certain way its being red. In De Anima 3.8, Aristotle tells us that every sense organ becomes what it perceives and being red is a bodily thing. But mind is not doing that, it is simply being active in relation to its objects which are in themselves activity. Given this, we can say that my mind, insofar as it is active, is non-bodily, but there remains a question of if mind insofar as its passive is entirely separated from body. A reason to think that passive mind is entirely non-bodily is the idea that it needs to have infinite potentiality. However, a reason to think that mind is not entirely non-bodily is the claim that Aristotle makes in De Anima 3.5 that passive mind is destructible.

At the beginning of De Anima 3.5, Aristotle wants to talk about active mind instead of passive mind. Aristotle introduces this discussion with the claim that, in general, we are going to get an active and passive structure for everything. That is, everything in the universe has an active side and a passive side. The principle that no matter what we are talking about, we are always talking about a relation between an active thing and a passive thing is a universal principle in Aristotle’s ontology and metaphysics. When we talk about any concrete thing like a person, we can say that there is an active thing, a soul, realized in a passive thing, a body, and the combination of these two things together is what makes a person. A power of the soul itself has an active side and a potential side. On the active side, there is seeing and on the potential side there is sight or sightedness. That is, one would still have the passive thing, sight or sightedness, when one is asleep. One is not seeing anything, but one still has the power of sight. However, when one is awake in a well-lit room, one is actually seeing things and this is an activity. This structure follows for mind as well, so mind will also have an active side and a passive side. In De Anima 3.4, Aristotle discusses passive mind and in De Anima 3.5, he discusses active mind.

Active mind is different from passive mind. That is, he is able to draw distinctions between the two. Specifically, on this question of perishability. Aristotle begins with the thought that: “mind as we have described it is what it is by virtue of becoming all things while there is another which is what it is by virtue of making all things as if it were a positive state like light” (De Anima, 3.5). Aristotle says that the active mind makes all things as if it were like light. In the case of sight, there is an eye and several objects in front of it in a room. If it were dark, you would not see anything. For Aristotle, light is a quality of a medium. The air in this environment is either dark or lit. If it is lit, it becomes actively transparent as opposed to potentially transparent. For Aristotle, what it is for a body of air to be dark is for it to be opaque whereas what it is for a body of air to be lit is for it to then become transparent. What the objects in front of the eye have is a potential to produce a color which is only activated in a lit medium and they produce a color in relation to a possible observer. Strictly speaking, the objects are actively having or presenting a color only when somebody is looking. In particular, something is presenting a color only when the medium of the eye is colored similarly. In this description of sight, light is a maker in that it makes the power of the objects to produce or present color actual. Light does not make the objects the color that they are in the sense that it determines their color, but light does make the objects colored in that they cannot present their coloredness except in the presence of the light. Therefore, what Aristotle means when he says that mind makes all things is something like mind is that in virtue of which something can present itself as that thing.

Aristotle wants to vindicate Anaxagoras’s claim that mind is impassable, unmixed, and separable. Aristotle’s explanation for why this is the case is that mind is an activity and all activities are impassable, unmixed and separable. In the case of a housebuilder, the housebuilder is mixed with many things, but the house building activity is not mixed with anything, it is separate, and purely active. This is not because the housebuilding activity is somehow divine, but because when we talk about the activity of housebuilding, we are focusing on that one activity and ignoring anything else that may be happening to the housebuilder like the color of his hair. To talk about the activity in which something is engaged is already to logically separate these things from one another. To refer to a housebuilder is to collect these things which are mixed together in the individual. However, insofar as I am listing these things, I am talking about actualities. Insofar as I am drawing these actualities out logically, they are all impassable, unmixed, and separate. Mind is an activity, and every activity is like this, this is why Mind is impassable, unmixed, and separate.

In De Anima 3.4, we get two puzzles with the suggestion that mind is not bodily. The first is the question of how mind could come to think at all given that it is impassable. The second puzzle is that if mind is thinking per se and is one in kind with what it thinks, then mind will have to either belong to everything or have some element that belongs to everything or that it shares with everything. In resolving the second puzzle, Aristotle says that mind is thinkable in exactly the same way as its objects are: “in the cases of objects that involve no matter, what thinks and what is thought are identical. For speculative knowledge and thought and its object are identical.” Aristotle presents the question of why mind is not always thinking. His answer, is that mind is always thinking. For Aristotle, active mind is an eternal and immortal feature of the universe. If active mind is like the light in a room, the room is always lit. The analogy that Aristotle is trying to draw is that passive mind is to beings as eye is to color. Passive mind, insofar as it is analogous to the eye, is destructible. The idea is that we have a logic of receptivity that is being governed by the simplicity of the object. The subject matter of De Anima 3.4 is to parse apart, given the similarity of structure, perception from thinking. For Aristotle, the only grounds for doing so are that thinking cannot be bodily because it has to have a wider range. Perception is only about things like colors or sounds whereas thinking needs to be about everything. However, this is the only distinction Aristotle draws between the two faculties. The whole point of De Anima 3.4 is to make the claim that mind is independent from the body and therefore it is different from perception.