Some of the problems of making literalism consistent with the various claims and arguments
that Aristotle makes in theParva Naturaliahave to do with the media of sense. First, if
literalism is true for the organs of sense, what of the media? That is, do the various media too
literally take on the properties of the objects that they are conveying to the organs of sense?
This has been used as the basis forreductioarguments against literalism. Alexander argues
that we do not observe either the organ or the medium taking on colour. Indeed, he argues that
this cannot be the case for if a white man and a black man were to face each other, the
intervening space does not impede in their respective perceptions of the other. Thus, the
medium does not change, at least not qualitatively.33
The second problem is that literalism brings into question the necessity of media. In his
argument for the necessity of media (see below) Aristotle argues that they are needed because
we do not see objects placed directly on the eye. If literalism holds, then when I see an apple I
perceive “red” just because my eye becomes red, and presumably, this is due to the medium
between the apple and my eye also being red. But if the medium becomes red, then why is it
that we cannot perceive the red apple when it is placed directly on the eye? It seems that if
literalism is true, then media are redundant.
The argument for the necessity of media runs as follows:
The following makes the necessity of a medium clear. If what has colour is placed
in immediate contact with the eye, it cannot be seen. Colour sets in movement
what is transparent, e.g. the air, and that, extending continuously from the object
to the organ, sets the latter in movement. Democritus misrepresents the facts
when he expresses the opinion that if the interspace were empty one could
distinctly see an ant on the vault of the sky; that is an impossibility. Seeing is due
33AlexanderDA 62, 1-13. The distinction that commentators work with is between the medium becoming
affected materially or qualitatively. The more controversial claim is the latter, which is denied by most, the exception being Themistius, who argues that the medium for touch must be affected qualitatively. See Themistius
to an affection or change of what has the perceptive faculty, and it cannot be affected by the seen colour itself; it remains that it must be affected by what comes between. Hence it is indispensable that there be something in between—if
there were nothing, so far from seeing with greater distinctness, we should see
nothing at all. (419a12ff)34
In this passage Aristotle argues that colour is needed to set the transparent in motion, which is
needed for sight. What is capable of becoming coloured is the colourless (418b27). Note that
we get a formulation of the Plasticity Principle such that the medium and organ of sight are
transparent in order to take on the colours of things. Whatever is visible is colour, and it is in
colour’s nature to affect the transparent.
The claim is that if an object abuts the eye there is no perception of colour. This follows
from Aristotle’s insistence that colour is situated on the surfaces of things. Inde Sensu3 he
writes:
But since the colour is at the extremity of the body, it must be at the extremity of
the transparent in the body... whether we consider the special class of bodies
called transparent, as water and such others, or determinate bodies, which appear
to possess a fixed colour of their own, it is at the exterior bounding surface that all
alike exhibit their colour. (439b10ff)35
The reasoning, then, is that if an object is placed against the eye then it effectively has no surface, thus no colour, and hence, no ability to change the transparent. Because of this, we
34 σημεῖον δὲ τούτου φανερόν· ἐάν γὰρ τις θῇ τὸ ἔχον χρῶμα ἐπ` αὐτὴν τὴν ὄψιν, οὐκ ὄψεται· ἀλλὰ τὸ μὲν χρῶμα κινεῖ τὸ διαφανές, οἷον τὸν ἀέρα, ὑπὸ τούτου δὲ συνεχοῦς ὄντος κινεῖται τὸ αἰσθητήριον. οὐ γὰρ καλῶς τοῦτο λέγει Δημόκριτος, οἰόμενος, εἰ γένοιτο κενὸν τὸ μεταξύ, ὁρᾶσθαι ἂν ἀκριβῶς καὶ εἰ μύρμηξ ἐν τῷ οὐρανῷ εἴη· τοῦτο γὰρ ἀδύνατόν ἐστιν. πάσχοντος γὰρ τι τοῦ αἰσθητικοῦ γίνεται τὸ ὁρᾶν· ὑπ` αὐτοῦ μὲν οὖν τοῦ ὁπωμένου χρώματος ἀδύνατον· λείπεται δὴ ὑπὸ τοῦ μεταξύ, ὥστ` ἀναγκαῖόν τι εἶναι μεταξύ· κενοῦ δὲ γενομένου οὐχ ὅτι ἀκριβῶς, ἀλλ` ὅλως οὐθὲν ὀφθήσεται.This paragraph is important for more than just this
chapter on sight and its medium, for it is the explicit reasoning behind the necessity of media quite generally in perception.
35
ἐπεὶ δ` ἐν πέρατι ἡ χρόα, τούτου ἂν ἐν πέρατι εἴη. ὥστε χρῶμα ἂν εἴη τὸ τοῦ διαφανοῦς ἐν σώματι ὡρισμένῳ πέρας. καὶ αὐτῶν δὲ τῶν διαφανῶν, οἵον ὕδατος καὶ εἴ τι ἄλλο τοιοῦτον, καὶ ὅσοις φαίνεται χρῶμα ἴδιον ὑπάρχειν, κατὰ τὸ ἔσχατον ὁμοίως πᾶσιν ὑπάρχει.
cannot see things which are so placed against the eye, and thus, media are required to enable
perception.
There are two parts to this argument. The first, as we just saw, establishes why we need
space between the object and organ. But Aristotle then goes on to say that this space must be
of a certain kind. That is, it cannot merely be empty space, for if this were the case then there
is no way to ground a relation of affection between the object and organ. If the interspace between object and perceiver were empty then we cannot explain how the object acts on the
organ to affect the change required for sensation. This is the reason why Aristotle rejects Democritus’ view. The eye cannot be affected by the object itself for as we have seen, even if the object were to touch the eye we have no sight, and the object cannot act at a distance. By
elimination, we are left with the conclusion that the eye must be affected by “what comes in between” (419a19:leipetai dˆe hupo tou metaxu).36 Thus using sight as his paradigm, Aristotle
reaches the conclusion that media are necessary for perception.
Although the argument for the necessity of media is raised in the chapter on sight and its
object, Aristotle intends it to apply the other senses in a like manner. He writes:
The same account holds also of sound and smell; if the object of either of these
senses is in immediate contact with the organ no sensation is produced. In both
cases the object sets in motion only what lies in between, and this in turn sets the
organ in movement: if what sounds or smells is brought into immediate contact
with the organ, no sensation will be produced. The same, in spite of appearances,
applies to touch and taste (419a25ff).37
Thus Aristotle at the very least intends his account to apply to all the senses.
The question then, is whether media are affected by objects and in turn affect the organs of
36Note that this argument is indifferent to the nature of perception. That is, it holds true for the literalist as well
as the spiritualist, for it is non-committal about the further issues of the role of the organs in perception, and what amounts to or is sufficient for perception.
37
ὁ δ` αὐτὸς λόγος καὶ περὶ ψόφου καὶ ὀσμῆς ἐστιν· οὐθὲν γὰρ αὐτῶν ἁπτόμενον τοῦ αἰσθητηρίου ποιεῖ τὴν αἴσθησιν, ἀλλ` ὑπὸ μὲν ὀσμῆς καὶ ψόφου τὸ μεταξὺ κινεῖται, ὑπὸ δὲ τούτου τῶν αἰσθητηρίων ἑκάτερον· ὅταν δ` ἐπ` αὐτό τις ἐπιθῇ τὸ αἰσθητήριον τὸ ψοφοῦν ἢ τὸ ὄζον, οὐδεμίαν αἴσθησιν ποιήσει. περὶ δὲ ἁφῆς καὶ γεύσεως ἔχει μὲν ὁμοίως, οὐ φαίνεται δέ.
sense, and if so, what is the nature of the affection in the media. It seems that Aristotle does think that media are affected. In discussing the necessity of sentience for survival in Book III of thede Anima, he notes that animals must be (and obviously are) able to perceive things
from a distance as well as by immediate contact. To perceive from a distance, he adds, is
possible only through media. To this he adds:
This will be possible if they can perceive through a medium, the medium being
affected and moved by the perceptible object, and the animal by the medium (434b28).38
Although he is explicit here that the medium is indeed affected by the object in order to affect the organ,39it is unclear from this passage whether this affection is of the same kind as that of
the organ—a qualitative affection. The picture, however, can be filled in given the kind of change that the mean enables in the organs of sense, which we do not find in the media.
The medium of sight is affected by the object and in turn affects the eye enabling the eye to become like the object in the relevant sense taking on its colour. The medium, like the eye,
becomes coloured—i.e. it is affected qualitatively—but it does not perceive because it cannot change in the way required for perception simply because it lacks a homeostatic mean. But if
the medium, like the eye, becomes red, then we face Alexander’s worry for we should see the
interspace between the object and the eye too as red. It is in the nature of the transparent to
take on colour. Upon perceiving a red object the transparent medium of sight thus becomes
red too. But Aristotle is not threatened by Alexander’s worry, for as he notes in thede Sensu
passage above, things are only coloured on their “bounding surfaces”. Thus, Alexander’s
worry is misplaced. The medium of sight is not itself seen for the simple reason that it is
transparent save for its surfaces.40 The coloured surfaces are thus those where the medium is
38
τοῦτο δ` ἂν εἴη, εἰ διὰ τοῦ μεταξὺ αἰσθητικὸν εἴη τῷ εἰκεῖνο μὲν ὑπὸ τοῦ αἰσθητοῦ πάσχειν καὶ κινεῖσθαι, αὐτὸ δ` ὑπ` ἐκείνου.
39In the first two chapters of Book V of theGeneration of Animals, Aristotle re-examines the nature of the
activity in the media during perception. He concludes that media do affect objects just because they too are in motion, otherwise they would be un-moved movers.
affected by the object and where the medium affects the organ. The idea, then, is that media are necessary for perception because the senses cannot act at a distance, nor can we perceive
objects in direct contact with the organ, and the media, like the organs, take on the properties
of the objects of sense.
What is both interesting and unique to the literalism implied by this reading of the mean is
that it explicates the nature of the change inherent in any act of perception, to which we will
return below. An accurate understanding of the mean allows us to elude the most threatening
criticisms of literalism.