Aristotle’s Revenge and naïve color realism

The American Catholic Philosophical Association meeting in Minneapolis this November 21-24 will be devoted to the theme of the philosophy of nature.  On the Saturday of the conference there will be an Author Meets Critics session on my book Aristotle’s Revenge.  It will be chaired by Patrick Toner and the speakers will be Robert Koons, Stephen Barr, and myself.

While we’re on the subject, I’d like to call your attention to a couple of very interesting responses to Aristotle’s Revenge, the first from Nigel Cundy at The Quantum Thomist and the second from Bonald at Throne and Altar.  Both writers know the relevant science and both are open-minded and knowledgeable about the relevant philosophical ideas too.  Both seem largely sympathetic to the book but also raise serious criticisms.  They cover a lot of ground (since the book itself does) so there’s no way I can respond to everything they say in one post.  So this will be the first in a series of occasional posts responding to their criticisms.

The general project

Let me start with some general remarks about the project of the book.  Its main thesis is that the fundamental notions of Aristotelian philosophy of nature – the reality of change, the theory of actuality and potentiality, hylemorphism, efficient causality, teleology, the intelligibility of nature – cannot be entirely eliminated from a coherent picture of physical reality.  They are like J. L. Austin’s frog at the bottom of the beer mug, or the whack-a-mole that pops up somewhere else just when you thought you’d knocked it down.  Even if you could banish them forever from this or that particular part of nature, you can never extirpate them from nature as a whole.  Certainly modern science has not done so, and cannot do so.  So I argue.

At the very least, I argue, they cannot be banished from any coherent conception of scientists themselves qua embodied subjects theorizing about the world and testing their theories via observation and experiment.  You cannot make sense of how all that works – of what it is to be a conscious subject with a stream of thoughts and experiences, representing the world theoretically and manipulating scientific equipment, etc. – without implicitly supposing that change is real, that it involves the actualization of potential, that efficient and final causality are real, and so on.  The scientist himself is, in effect, an impregnable fortress from which the Aristotelian cannot be pushed out.  That is the fundamental way, though by no means the only way, that science presupposes Aristotelianism.  And the reason it is not more widely noticed is the same reason why, as Orwell said, one does not notice what is right in front of one’s nose.  The scientist looks out toward the world described by physics, and Aristotle is nowhere to be seen – but only because he is sitting right there next to him.

Furthermore, physics in any case captures abstract structure rather than concrete content, so that the absence of the key Aristotelian notions from its description of basic physical reality by itself tells us precisely nothing about whether the notions really correspond to anything in basic physical reality.  Their absence reflects merely the methodology of physics, not anything about the inner nature of the reality studied by means of that methodology.  This epistemic structural realist account of physics is a second general theme of the book. 

A third general theme is the poorly thought through nature of the purported mechanistic alternative to Aristotelianism.  The mechanical world picture has always been more a rhetorical posture than a worked out alternative philosophy of nature.  Where it claims to offer alternative explanations to those of the Aristotelian, in fact it merely pushes back questions to which an Aristotelian answer will ultimately still have to be given, or simply offers no explanation at all.

So, this is the “big picture” vision of the book.  First, physics – and by extension the other sciences that take its account of the physical world for granted – couldn’t of their nature tell you one way or the other whether an Aristotelian philosophy of nature or a rival mechanistic position is true.  Second, the mechanistic alternative isn’t coherently worked out anyway.  And third, in any event there is no way in principle entirely to chuck out the basic Aristotelian notions.  They will stubbornly remain forever ensconced within the fortress of the scientist himself qua embodied, thinking, conscious subject.  These points, I argue, are unaffected by whatever we end up saying about the nature of time, space, and motion, whatever we say about reductionism in chemistry and biology, whatever we say about evolution, etc.

But the Aristotelian can in fact say much more about these details too, and that is the secondary thesis of the book.  If “the big picture” is about defending the fortress, “the details” concern questions about how much territory can be reconquered by the Aristotelian in the various regions of the philosophy of time and space, the philosophy of matter, the philosophy of biology, and so on.  And so I then go about developing lines of argument to show how territory in these different areas might indeed be reconquered.  For example, I defend an A-theory of time in general and presentism in particular, I argue against reductionism in chemistry and biology, propose an Aristotelian interpretation of evolution, and so forth.

Now, the main thesis or “big picture” of the book does not stand or fall with particular arguments having to do with the secondary theses concerning “the details” – with, say, what I argue concerning the presentist view of time, or my take on the metaphysics of evolution.  One could reject what I say about one of these secondary issues while agreeing with what I say about other secondary issues, or one could even reject everything I say about these secondary issues while agreeing with my “big picture” thesis.

I emphasize all this because some readers are bound fallaciously to suppose that if they can refute what I say about one of these secondary matters, they will thereby have undermined the general Aristotelian philosophy of nature.  Nope.  It’s not that easy.  If the Aristotelian has to fight on many fronts, so too does the anti-Aristotelian.  And if my “big picture” thesis is correct, the anti-Aristotelian could win almost every battle and still lose the war.

Now, back to Cundy and Bonald.  As far as I can tell, at least for the most part they don’t have a problem with what I am calling the “big picture” thesis, and even sympathize with it.  Their objections have to do with what I am calling “the details,” and even then only some of those details.  That is important context for what I will have to say in response.

Naïve color realism

In the remainder of this post I’ll focus on Bonald’s remarks about the physics and philosophy of color.  I’ll turn in later posts to what Cundy and Bonald have to say about other issues, such as presentism.  A standard reading of the revolution made by modern physics holds that it refuted our commonsense understanding of color (alongside other so-called “secondary qualities”).  The idea is that what commonsense regards as redness, for example, exists only as a quale of conscious experience and that there is nothing in mind-independent reality that is really like that.  What there is in mind-independent reality is instead merely a surface reflectance property that is causally correlated with the quale in question.  We can redefine “redness” so that it refers to this property, but the commonsense notion of redness applies only to something subjective, something existing only in consciousness.  And the same can be said for all other colors.  Common sense is committed to the “naïve color realist” view that something like color as we experience it exists in mind-independent reality, even apart from our experience of it.  But physics, it is claimed, has refuted this.

Endorsing arguments developed by contemporary philosophers like Hilary Putnam, Barry Stroud, and Keith Allen, I propose in Aristotle’s Revenge that something like naïve color realism can in fact still be defended.  (See especially pp. 340-51.)  And part of the background of the defense of this claim is the more general theme of the book that physics does not in any case give us an exhaustive description of matter, but captures only those aspects susceptible of mathematical description.  Hence we should not be surprised if its description of matter fails to capture color as common sense understands it.

Now, in response to this, Bonald makes the following remarks:

[T]he claim that physics necessarily leaves out information about the physical world is a radical one.

It does nothing against Feser’s claim to point to the astounding reliability of physics, because physics could be perfectly reliable in its own order while completely ignoring features outside this order. However, if claims of the limitations of physics are to be more than gestures of epistemic humility, we must have some independent source of information.  Feser sometimes thinks he can get this from our manifest image “common sense” experience/conceptualization of the world, but I find this questionable.

For example, in a section on secondary qualities, Feser rightly objects to claims that color is a mere subjective experience. Physics has clearly established that color is the wavelength of visible electromagnetic waves. But Feser dismisses this account of color as not being “color as common sense understands it”, so that the world of physics is still in some esoteric way colorless. I do not understand this at all. Common sense is not an understanding of light rival to that of optics; it’s not an understanding at all, but a bare experience of it. The qualia of colors (the only thing physics clearly does not provide) have no independent structure, which allows us to identify them simply as the experience of light at different wavelengths. The color of physics, meanwhile, explains all our experiences of color: the blueness of the sky, the order of colors in the rainbow, the red glow of a hot stove… What else is there?

End quote.  Now, if I correctly understand Bonald’s criticism here, what he is saying is that it is a kind of category mistake to suppose that the qualia that physics leaves out of its story about color have anything to do with color as an objective feature of physical objects.  Suppose we distinguish between RED (in caps) and red (in italics) as follows:

RED: the qualitative character or qualia of the color sensations had by a normal observer when he looks at fire engines, “Stop” signs, Superman’s cape, etc. (which is different from the qualitative character of the sensations had by e.g. a color blind observer)

red: whatever objective physical property it is in fire engines, “Stop” signs, Superman’s cape, etc. that causes normal observers to have RED sensations

What Bonald seems to be saying is that while physics tells us nothing about RED itself, it does tell us everything there is to know about red, including what it is about red objects that makes them generate RED sensations in us.  To be sure, physics tells us nothing about what it is about the brain that accounts for our sensations being RED, but that’s a different question – one for psychology, neuroscience, and philosophy of mind.  In any event, it is (Bonald seems to think) a mistake to think that RED has anything to do with red.  RED has to do with the mode in which the human mind perceives color, but red has to do with color itself as an objective feature of things.  What we know about RED tells us no more about red than what we know about the structure of the eye or the optic nerve does.  Like the eye or the optic nerve, RED is something in the perceiver, not something in the world the perceiver perceives.  And something similar could be said about other colors.

A comment Bonald makes in response to a reader seems to me to confirm this interpretation of his position.  And what he seems committed to is essentially Locke’s version of the distinction between primary and secondary qualities.  To be sure, Bonald evidently rejects some versions of that distinction.  But Locke’s way of putting it is to acknowledge that both primary and secondary qualities are really in physical objects themselves, but then to hold that whereas primary qualities produce in us sensations that resemble something in the objects, secondary qualities produce in us sensations that do not resemble anything in the objects.  Hence, Locke would agree with common sense that physical objects really are red.  But he would identify red with red and say that common sense is mistaken to hold that there is anything in physical objects that resembles RED.  And that seems to be pretty much Bonald’s view (again, if I understand him correctly).

Now, if that is indeed what Bonald is saying, then what I would say in response is this.  First, we need to distinguish two issues:

(1) Is there good reason to believe that physics does not in fact capture everything there is to red, and that common sense is (contra Locke) after all correct to suppose that there is in red something that resembles RED?

(2) Exactly what is the ontological relationship between this something-that-resembles-RED that is in red, and what physics tells us about red (e.g. surface reflectance properties)?

Now, in Aristotle’s Revenge, what I focus on is question (1).  In particular, with Putnam, Stroud, Allen, et al., I set out some considerations that support an affirmative answer to that question.  But I do not really have much to say there about question (2).  Now, Bonald, as far as I can tell, does not really address what I have to say in support of an affirmative answer to (1).  Rather, I think he is essentially expressing doubt that the naïve color realist could provide a good answer to (2), and is skeptical of naïve color realism for that reason.  He doesn’t try directly to show that the arguments for the affirmative answer to (1) are wrong, but rather merely suggests that it is hard to see how the affirmative answer could be true.

If this diagnosis is correct, then Bonald has not really answered the heart of my case for naïve color realism.  But it is only fair to acknowledge that he nevertheless raises a very important question, and a difficult one.  And question (2) is difficult precisely because our experience of color is indeed to a considerable degree contingent upon the nature and condition of the nervous system and the sense organs, and on the circumstances of observation.  If the arguments I defend in the book are correct, that does not suffice to refute naïve color realism.  But it does make it difficult to disentangle the aspect of RED that is objectively there in red itself and the aspect that is contributed by the mind.

But that brings me to the second point I want to make in response, which is that it is a mistake to suppose in the first place that we need to disentangle such aspects in order for RED to correspond to something in red.  What I have in mind might be made clear by considering some parallel cases.  I present these tentatively, and regard the analogies only as suggestive and not perfect.

First, consider the problem of universals.  According to the Aristotelian realist approach to the problem, humanness exists as a universal only insofar as it is abstracted by the intellect from particular individual human beings.  Outside the intellect, there is the humanness of Socrates, the humanness of Alcibiades, the humanness of Xanthippe, and so on, but not humanness as a universal divorced from these particulars.  There is a sense, then, in which humanness qua universal depends on the mind, but not because it is the free creation of the mind.  It is not.  What the intellect abstracts is something that already really exists in the particular things themselves, but it exists there in an individualized way.  It is only qua universal and thus qua abstracted from the individuals that it depends on the mind.  So, a universal like humanness is both dependent on the intellect and grounded in mind-independent reality, and it is a mistake to think that it has to be the one to the exclusion of the other.

Now, in an analogous way, I would suggest, the something-that-resembles-RED that is in red can both be grounded in mind-independent reality and at the same time depend in part on the mind for its existence.  It might really be there in red objects and be irreducible to what physics has to say about red, even if it is only actualized when a perceiver perceives it.  (That is not to say that this something-that-resembles-RED that is in red is to be thought of as a universal.  I’m not saying that naïve color realism is the same as the Aristotelian realist approach to universals, but merely drawing an analogy between the two.)

Here’s a second analogy.  Thomists take transcendentals like being, truth, and goodness to be convertible with each other, the same thing looked at from different points of view.  Hence truth is being qua intelligible, and goodness is being qua object of appetite.  But that truth and goodness are to be characterized by reference to the intellect and appetite doesn’t make them the creations of intellect or appetite or imply that they don’t exist in a mind-independent way.  Similarly, though the something-that-resembles-RED that is in red is to be characterized by reference to the mind that perceives it, it can still exist in a mind-independent way.  (That is not to say that this something-that-resembles-RED that is in red is to be thought of as a transcendental.  Again, I am simply drawing an analogy.)

Putnam sometimes liked to say that “the mind and the world together make up the mind and the world.”  I certainly would not endorse everything Putnam associated with that slogan.  But it is a colorful (as it were!) way of summing up the point that it is a mistake to think that every aspect of reality must be characterizable either in an entirely mind-dependent way or an entirely mind-independent way.  Characterizing some aspects of reality might require reference both to the mind and to the mind-independent world, without the relevant components being separable into discrete mind-dependent and mind-independent chunks.  Color would seem to be an example.

Here’s a final and different sort of consideration that might help clarify the relationship between what I am calling the something-that-resembles-RED that is in red, on the one hand, and what physics tells us about red on the other.  The version of essentialism associated with contemporary analytic philosophers like Putnam and Saul Kripke tends to identify the essence of a thing with the hidden microstructure uncovered by science.  But Aristotelian-Thomistic essentialists regard this as a mistake.  The essence of a thing is not reducible to its microstructure, even if specifying the essence requires reference to the microstructure.  (See e.g. David Oderberg’s discussion at pp. 12-18 of Real Essentialism.) 

In light of this, we might say that what physics tells us about red is its microstructure, but that red isn’t reducible to that microstructure.  There is in red, in addition to its microstructure, something-that-resembles-RED.