3*. Plato, Soul and ‘the Unity of Apperception’

Plato introduced the topic called ‘the unity of apperception’ in his Theaetetus.† There Socrates asks Theaetetus whether we see with our eyes, or rather through them, i.e. by means of them; whether we hear with our ears or through them. Theaetetus answers ‘through’, and Socrates commends him for his decision, saying how odd it would be ‘if there were a number of senses sitting inside us, as if we were wooden horses, and there were not some single form (soul or whatever one ought to call it) in which all of them converge, something with which, through the senses as instruments, we perceive all that is perceptible’.

Plato did not treat this as a problem or puzzle, a matter arousing perplexity about the senses. Nor am I sure that Kant did, in giving it the name ‘the unity of apperception’. In this century, however, it is more likely to be seen as a puzzle. You hear a bang and see a flash. You hear and see the bang and the flash simultaneously. That is not yet enough to raise a problem: as Kneale has remarked, John might hear the bang at the same moment as Tom sees the flash and that observation is unproblematic, and it would remain so even if just one—John, say—hears the bang and sees the flash at the same time. A problem arises only for one person’s being conscious of both hearing a bang and seeing a flash at the same time. The perception of the simultaneity can’t be by sight or by hearing. How then can there be such a perception? By what sensory faculty does one perceive this?

Plato doesn’t have this example or indeed show a feel for this problem in the Theaetetus. He is after other game. There must be some one form of thing in which all the senses converge. This thing is a part of the perceiver. Can it be a part of his body, as the special sense organs are? What is perceived by means of one of them can’t be perceived by means of another of them. So if there is a thought about both, this can’t mean that there is a perception of both at once through either one of the special senses or the other. Through what then are you thinking of both? Suppose it were possible for you to try and find out whether sound and colour were both brackish, you’d find this out by the faculty that uses the tongue. Well, then, through what faculty do you get ‘exists’, ‘doesn’t exist’, ‘are alike’, ‘are unalike’, ‘the same’, ‘different’, and unity and numbers and their properties like odd and even? Theaetetus both grasps and helps to elaborate the question, and delights Socrates by saying ‘there isn’t any special organ for all these things—the soul itself is its own instrument for contemplating these common terms which apply to everything.’ Does Socrates, like Berkeley, insist that no sensory power can take in both objects of sight and objects of another sense? Not exactly. He does seem to suggest this when he says ‘suppose it were possible to try and find out whether sound and colour were both brackish’. That is, he refers implicitly to the impossibility. But the point here is not that impossibility: he wants to suppose (per impossibile indeed) that you could try and find this out but his purpose is only to elicit the realisation that it would be by the exercise of a faculty other than sight or hearing—the faculty that uses the tongue. His aim is to elucidate the question he wants to ask. Through what instrument do you tell that the objects of sight and hearing are, say, existent, unlike, different, and numerous? If you could find out they were brackish it would be by means of the tongue. Well, you actually can say those other things about them. What’s the faculty, what’s the instrument? Is it part of the body as the special sense organs are?

We do indeed have Plato making Socrates assert that what is perceived by one of the special senses can’t be perceived by another of them. Object and sense-faculty are correlative: more precisely, they are related by a many-one relation. If O is object of special sense faculty F, it is not an object of any other special sense faculty. So red, for example, is an object of sight and cannot be object of any other special sense. But the relation is not one-one; for the fact that red is an object of sight does not imply that nothing else is—blue is, for example. Thus it is only many-one and not one-one.

The only sensory powers and objects that Plato mentions in this discussion are the special ones, the ones that Aristotle later called ‘proper’ or ‘peculiar’. It’s probably most natural for us to call them ‘particular’ senses. And Plato certainly seems to hold that no such sensory power can take in any such object of another such sensory power. The point is hardly controversial. But Berkeley’s thesis is a much stronger one—there cannot be a sensory power that takes in objects which another sensory power also takes in. What has Plato to offer about this in the Theaetetus discussion? Nothing! He does not mention any properties that strike one as ‘common sensibles’. He does not mention shape and size, for example. Concerning these, Berkeley said that truly visual shape and size are hardly ever mentioned or considered. But he is quite sure they exist and are not the same properties as the size and shape perceived by touch. Thus he denies the existence and indeed the possibility of common sensibles. Plato does not here consider this, except in the way of considering whether there is some faculty using a corporeal sense through which the soul perceives existence, resemblance, same and different, unity and number, odd and even. Of these only unity and number counted among Aristotle’s ‘common sensibles’. But Plato’s interest is evidently not in the topic of common sensibles, let alone a common sense by which they are taken in, but rather in the question whether that list—existence, same, different, etc,—is a list of things apprehended, as the objects of the particular senses are, by a faculty using a part of the body as an organ. And his answer is evidently: no. His interest is in that list and the power being exercised in the formation of judgments using members of it. For example, that sound and colour are not the same. The question is whether ‘same’ and ‘not the same’ can be referred to some special faculty as colour can be referred to sight.

Let us now consider Socrates’ commendation of Theaetetus for his ‘thought’. We can see what Plato means by ‘with’ as opposed to ‘through’. At first sight it sounds as if the senses are supposed to be windows through which the soul sees and hears, sitting within. But the reference to instruments shows that that is not what is intended: the soul uses the sensory powers as instruments in perceiving their objects. Therefore, as this is the explanation of ‘through’ in contrast with ‘with’, he doesn’t intend the rejected proposition ‘He sees with his eyes’ to be understood instrumentally (he is not denying that eyes are instruments of sight); nor, when he accepts talk of the soul as something with which, through the senses, we perceive all that is perceptible, does he intend to suggest that the soul (or mind) is itself an instrument we use, with which we perceive, think and so on.

I take it that we are to understand the Greek dative or our ‘with’ in such a way that, if you do something with something, e.g. you walk with your legs, the first something is actually done by the second something; your legs walk, you walk with your legs. This walking of your legs is, we may note, an exercise by you of the power of walking. If there is ‘a single form, call it the soul, with which through the senses, we perceive’, then it is the soul that perceives, not the sense organs, and our soul’s perceivings are our exercisings of our powers of perceiving. That’s the meaning of ‘one perceives with one’s soul’. It itself is what has the objects as objects of perception or thought. When those objects are objects of the special senses there is also the instrument, the sense organ through or by means of which the soul perceives.

To sum up: if I am right in my understanding of the matter, the difference between the legs and the sense organs is that the legs do walk, and are not instruments by means of which the soul walks; the eyes, on the other hand, do not see, but are instruments by means of which the soul sees. There is nothing with which the soul perceives or thinks as the animal walks with its legs, except indeed itself.

But, we may ask, should we not say that the eye sees, the ear hears, the skin is sensitive, the olfactory apparatus smells, the tongue and palate taste? The answer to this must be found in the comparison with men sitting in the Trojan horse. Each of these men judges things himself. If the eye sees and we see with our eyes in the way I have explained, then the eye itself would be a judging subject. But as the eyes and the sense of sight cannot take in sounds, each of us would be or contain a whole set of distinct judging subjects. But there are judgments which concern the special objects of the particular senses, and whose expressions include terms like ‘same’, ‘exists’, etc., which are not names of objects of sense perception. Therefore there must be some single thing which takes in the special objects of the particular senses and frames judgments containing terms for them as well as those other terms which do not stand for special objects of particular senses.

All this quite by-passes the topic of common sensibles. All we have in Plato are: objects of the particular senses, and here there is always a sense organ which is a particular bodily part; and terms standing for what according to Socrates and Theaetetus are not objects of sense at all, for there is no organ. But what perceives the objects of sense and also has as its objects existence, like and unlike, same and different, one and many, is the soul. ‘Soul’ is introduced only as a possible term for that necessary single thing in which all the senses converge. That they do so converge and so that there must be ‘some one thing’ is proved by the fact that one can think such things as ‘sound and colour are different’.

The argument seems to me to be a good one and for the moment the thing that bothers me is the total bypassing of the topic of common sensibles. I have mentioned that Berkeley rejected these: at least he rejected shape and size as common to sight and touch. I see no reason why Plato should have rejected them. The objects of sight are colours, light and darkness. To say that is not to say that there cannot be any other objects of seeing or that such other objects can’t be also objects of tactile feelings. Objects so apprehended by more than one sense don’t thereby have to have a ‘special’ sensorium, what Aristotle calls a κοινον άισθητηριον, a common sensorium of their own. To call them common sensibles is to say they are common to more than one sense, not to say they are the objects of a new particular sense, oddly called ‘common’. And indeed Aristotle seems a bit ambiguous, on occasion denying the possibility of any such κοινον άισθητηριον, I think for the reason I’ve just given.

On the other hand, there is the following question: Is there not such a thing as a perceptual judgment? Say: ‘This object (whatever it is) is blue’, or ‘This is a chord, two or three notes combined’. We need enter into no dispute here about whether perception is judgment. We need not quarrel with Plato about the soul being what sees and hears. He, just because he thought that, would have no difficulty, I should think, about the idea of a perceptual judgment. Judgment being an act of mind, that there are judgments on the ‘recepta’ of sense whose very reception is itself an act of mind, or soul, would be unproblematic for Plato. As for other people who perhaps don’t go along with Plato, we can simply point to examples of perceptual judgment.

Now ‘Sound is not the same as colour’ is not a perceptual judgment: for I lay it down that a perceptual judgment is particular, always involving something one could point to, a particular occurrence, some object of sense. Here I am Humpty Dumpty and claim to tell the phrase ‘perceptual judgment’ what it is to mean. Under these orders, a perceptual judgment restricts itself to being a judgment about something that is or was being perceived, and any such thing, if the being perceived comes essentially into the judgment, makes the judgment a perceptual one, so long as it is simple. By ‘simple’ I mean neither conditional nor general. Let this suffice as an explanation. Now aren’t ‘This pattern of colours is gayer than that tune’ or our old friend ‘The bang was simultaneous with the flash’ perceptual judgments? If we allow ourselves to call ‘This is blue’ a deliverance of sense, should we not also call those judgments deliverances of sense? How might Plato express this? Just by saying that in these cases the soul perceives and judges something about what it perceives. What is involved is a sensory power, surely; but the simultaneity of the bang and flash, or greater gaiety of the colours than the tune are not objects of either sight or hearing, although sight and hearing are also involved.

Berkeley would not have granted that there were sensory judgments. Here apparently he has a recourse available. He could make use of his thesis that there are no ideas of relations; for a relation involves a comparing mind and nothing involving a comparing mind can be given in sense. I protest against this: many relations between objects of sense are just as perceptible as non-relational sensible properties. ‘This blue’, I say with my eye on a pair of blue ribbons, ‘this blue is darker than that one’. After all, Berkeley thinks that perceiving too is an act of mind, hence that perceiving is not an idea, perceiving is not perceived. That didn’t mean that there were no ideas which were perceived: in fact ideas are the very thing whose being is to be perceived. In giving expression to a perception, then, you aren’t using the concept of perception. No more are you using the concept of a comparison when you compare or of a comparing mind when you judge one colour sample to be lighter than another. So he has no right to that thesis that there are no ideas of relations and hence that ‘The bang and the flash are simultaneous’ isn’t a perceptual judgment.

If then there are perceptual judgments straddling different sense modalities, haven’t we got a problem which is not solved by saying: the unitary item in which the senses converge is the soul? If there is an argument that the senses mustn’t be thought of as like a lot of men sitting in a Trojan Horse, but they must converge in some one thing, call it the soul; won’t there equally be an argument that they must converge in some one sensory power, call it the common sense, whose deliverances are still sensory?

I see no reason to think that Plato would have been disturbed by this. The ‘one thing, call it the soul’ does not have to be something unitary in the sense of having no departments—indeed we know that he believed in a tripartite division of the soul. Must there be a unitary, i.e. uniform, simple, constant character in the soul’s judging? Well, he doesn’t think so, as he distinguishes between what the soul uses instruments (sense organs) for and what it doesn’t. Might he say: where is the organ? With what bodily part is associated the sensory power through which the soul perceives simultaneity and greater or less multiplicity across different sense modalities?

This implies you can’t call something sensory unless there is an organ for that sensory power which it instances. This conception would mean that the fact there isn’t an organ would be a sufficient reason for saying this is a purely mental thing.

That the special senses have organs is true. It is not true that every different type of special sense object has a different organ. Aristotle remarks that taste would be counted part of touch if we tasted all over our bodies. And it is natural to regard hot and cold, rough and smooth, hard and soft, as different types; or again tingling, which hasn’t got a contrary; all are perceived through touch. Touch is, then, divided into many kinds of sensation. The skin isn’t the special organ of a special sense. But for simultaneity there seems to be no organ at all. And as it is a relation between the things called simultaneous you couldn’t handle it as we handled size and shape—saying it can be perceived by more than one sense.

Should I give up the idea that these judgments are perceptual judgments? Or should I say: they are so in as much as the perception of the bang and the perception of the flash are essentially involved in them; but ‘simultaneous’ is not a sensible characteristic—i.e. is never a sensible characteristic. Resemblance is not one either, though it can come into perceptual judgments. We would quarrel with Hume’s attempt to explain abstract ideas as different resemblances. If we form the idea of black and white and a cube and a globe because of the different resemblances to be found in a pair of cubes and a pair of globes, each pair containing one black and one white member, the question must arise how we derive ideas of resemblance since the resemblances are so different. Why are they all resemblances? Is that fact something sensory? It might be better to follow Plato and hold that resemblance like identity and difference are terms of intellect and not of sense. And so perhaps it is with simultaneity.

The thing that is striking about the terms that Plato chooses in order to give examples of thoughts about objects of sense, and ask ‘through what organ do you have these thoughts?’, is indeed that the terms are extremely abstract and general. Like and unlike, existent, same and different, number and unity, odd and even. They are as Frege might say: reason’s ownest own; they are properties (or whatever we choose to call them) grasped by intellect. What is here common to objects of sense is not grasped by the particular senses. So there seem to be two ways in which he reaches the ‘single form, call it the soul’. One is that it won’t do to picture the senses like the warriors sitting in the Trojan Horse, and the other is that the perceiver of objects of sense judges things about them (and thus has these too as his objects of thought) which specially belong to intellect, not to sense.

The bringing together in judgments that no particular sense could make—in case you think of the particular senses as making judgments—applies to a host of terms which appear to be sensory or perceptual in the sense I gave those words. If it is absurd to think of a faculty of ‘common’ sense, then these terms appear to be manufactured by the intelligence in a very complicated relationship to the special senses. It is here of great importance that the special senses are not confined to their own proper objects. One can see the expression of a man’s face, for example. Here we don’t invoke any sense other than sight; but the object of this seeing is not a member of the class: colours, light and darkness.

‘I do sensibly perceive the simultaneity of the bang and the flash.’ If this is a sense perception what is the organ of it?

‘There are two organs, eyes and ears.’

But neither of them is the instrument of this perception.

‘Both are jointly. The soul whose instrument they are, perceives the bang and flash through them and, being equipped with the concept of simultaneity, uses it in the judgment that it forms. The judgment is a perceptual one.’

But how does the soul perceive the simultaneity?

‘By simultaneously perceiving the bang and the flash and considering them under the aspect of the concept of simultaneity.’

But then it wasn’t a perception of simultaneity!

You are entangled in a prejudice about what to call a perception of something. You want to model it on the way the proper objects of the particular senses are perceived. It cannot be so modelled. That is what throws you into perplexity. The soul which is the life of the individual, is his vegetative and sensitive as well as his intellectual life and is able to acquire concepts in a great variety of ways. The sunflower turning to the sun is a bit of vegetative life. If the sunflower were an animal, its vegetative life would be greatly modified by that fact; but so would its animal life be modified by its vegetative processes. And if it were also intellectual and had a language this would affect its vegetative and animal life and be affected by it. So simultaneity of reaction in one form of life may become reaction to simultaneity in another and this become part of thought in the third.

You teach the concept of simultaneity by teaching a reaction to simultaneous events.

Hume may not have been so wrong as appears in explaining the idea of succession in terms of having a succession of impressions. Only he would have to grant that here the idea was not a copy of any impression, and in that way not derived from any impressions.

 

* From an undated, unpublished manuscript. Title supplied.

† See Theaetetus 184c and following for the part of the dialogue discussed in this paper.