Philosophy of nature and philosophy of [fill in the blank]

A reader of my recent post on the philosophy of nature asks some excellent questions:

I wonder, where does the philosophy of physics and in general the philosophy of science fall in between the scheme of metaphysics and philosophy of nature?...

Also, where does the discussion on the topic of the laws of nature belong?  Is that also philosophy of nature? 

Let’s start with the question of how the philosophy of science is related to the philosophy of nature.  Recall from my recent post that as the middle ground field of the philosophy of nature gradually disappeared off the radar screen of modern philosophy, the disciplines on either side of it -- on the one hand, metaphysics and on the other, empirical science (in the modern rather than Aristotelian sense of “science”) -- came to seem the only possible avenues of investigation of reality.  Recall also that the methodology of metaphysics came to seem a matter of “conceptual analysis,” while any study with empirical content came to be identified as part of natural science.  The very notion that there could be a middle ground field of study with empirical foundations but arriving at necessary truths, thus transcending the contingent world described by physics, chemistry, etc. and pointing the way to metaphysics -- as Aristotelian philosophy of nature claims to do -- was largely forgotten.

(The Aristotelian theory of act and potency is the classic example of such a piece of middle ground knowledge.  It is grounded in the basic empirical datum, the fact of change.  But it is not a description of this or that particular change or this or that particular kind of change but rather of all change as such.  Hence while empirically grounded it is not subject to falsification by theorizing in physics, chemistry, etc., because the phenomena dealt with in all such theorizing, since they all involve change, implicitly presuppose the theory of act and potency.  When the theory is worked out, though, it points beyond itself to the core theses of metaphysics, including natural theology -- indeed, as I have argued elsewhere, the theory of act and potency is the key to a sound natural theology.  It is no accident that contemporary philosophers who think metaphysics rests on “conceptual analysis” and who suppose the arguments of natural theology are just lame “god of the gaps” inferences have typically never even heard of the theory of act and potency.  As our friend James Chastek once aptly wrote, “a thomist could probably teach the whole history of modern thought as an overlooking of the distinction between potency and act.”  But I digress.)

A further background consideration is that while ancient and medieval philosophy tended to regard questions of ontology as fundamental and questions of epistemology as secondary, early modern philosophy essentially reversed this.  That is to say, the tendency of the ancients and medievals was to start with questions about what sorts of things exist and what their natures are, and then address the question of how we human beings come to have knowledge of the existence and natures of things.  (After all, to answer the latter, epistemological question you first have to know what a human being is, which is an ontological question.)  The early moderns tended to start instead with the question of how we can know anything -- where that question is understood, not the way an Aristotelian would understand it (as a request for an account of how distinctively human cognitive faculties work, etc.) but rather in terms of radical Cartesian doubt -- and only then, after addressing this skeptical question, to address questions of what sorts of things exist and what they are like.  (The bizarreries of rationalist, empiricist, and Kantian epistemology and metaphysics were the inevitable results of this perverse procedure.  But again, I digress.)  

Now, just as the Aristotelian-Scholastic understanding of metaphysics as grounded in the philosophy of nature gave way to the rationalist conception of metaphysics as grounded in innate ideas, which in turn gave way to the idea of metaphysics as “conceptual analysis,” so too did the Cartesian epistemology of the early moderns which had displaced the Aristotelian-Scholastic approach in turn give way to the linguistic emphasis of early twentieth-century analytic philosophy.  But whether framed in terms of rationalist or empiricist “ideas,” or Kantian “categories,” or the “formal languages” of the logical positivists, or the “ordinary language” of Wittgenstein and Ryle, or the various technical or commonsense “conceptual frameworks” of other writers, the result was invariably subjectivist -- philosophy as a kind of higher navel gazing, the study not of reality but of how we know, or conceptualize, or describe reality.  

Enter the philosophy of science.  The philosophy of nature is concerned with, well, nature -- with the same objective, material world studied by science, albeit it studies deeper aspects of that world than science does.  The philosophy of science is concerned -- or at least was, for most of its history, primarily concerned -- not with nature, but (no surprise) with science, with the disciplines that study the objective, material, natural world.   That is what it was bound to be concerned with given the developments I’ve described.  For with the virtual disappearance of the philosophy of nature and the reduction of metaphysics to “conceptual analysis” or the like, it came to seem that only empirical science could tell us anything about the natural world itself.  The most philosophy could do was address questions about how we know about or describe that world.  Hence for most of its history the philosophy of science was essentially concerned with questions about the methodology of science, the logical structure of scientific theories, the meaning of scientific assertions, and the like (and also, after Kuhn, Feyerabend, and Lakatos, with the history of science).  In other words, whereas the philosophy of nature (like ancient and medieval philosophy in general) had an ontological focus, the philosophy of science has historically tended (like modern philosophy in general) to have an epistemological (or at least logico-linguistic) focus.  Hence while science looks at the world, the philosophy of science looks at science looking at the world.

Now as I have said, that was true of the discipline for most of its history and for the most part.  But not entirely, and not so much these days.  For science, like ordinary experience, simply and unavoidably raises ontological questions it cannot answer.  What is it to be a law of nature?  What is it to be a cause?  Are the theoretical entities posited by physics real?  Are chemistry and biology reducible to physics?  What is a species?  Is science the only avenue of rational investigation of the world, even of the material world?  Philosophers of science were bound to address such questions, and as they addressed them -- and in particular, as they endorsed or at least entertained realist answers to such questions -- work in the philosophy of science started to reflect a concern with issues in what was traditionally known as natural philosophy or the philosophy of nature.  This is especially so in sub-fields like the philosophy of physics, philosophy of chemistry, and philosophy of biology, which are concerned with ontological questions no less than methodological or epistemological issues.  

So, though historically the philosophy of nature and the philosophy of science have tended to have significantly different concerns, recent work in the philosophy of science has included a consideration of issues that have historically been the concern of philosophy of nature.  And some contemporary mainstream writers on the philosophy of science would even go so far as to advocate at least a partial return to the specifically Aristotelian philosophy of nature that the early moderns rejected.  (For more on the Aristotelian understanding of the relationship between the philosophy of nature and the philosophy of science, see William A. Wallace, The Modeling of Nature: Philosophy of Science and Philosophy of Nature in Synthesis.)

While we’re on the subject, it is worth noting that other “Philosophy of…” sub-disciplines also seem to have their origins in the abandonment of the Aristotelian-Scholastic philosophy of nature.  Consider the philosophy of mind.  You won’t find ancient and medieval writers, or later Scholastic writers (well, with the occasional exception), devoting works to that subject.  You will find works on psychology, but “psychology” as they understood it is not merely the study of the mind.  It is rather the study of the soul, where for Aristotelian-Scholastic writers the soul is the form of a living thing, and where “form” is the principle of actuality correlative to “matter” as the principle of potentiality.  Hence “psychology,” for Aristotelian-Scholastic writers, is just that branch of the philosophy of nature devoted to the study of living things, and brings to bear on that study the main concepts of that more general discipline (act and potency, form and matter, efficient and final causality, etc.).  The study of sensation and imagination is part of the study of animal life specifically; and the study of intellect is part of the study of rational animals (i.e. human beings) even more specifically.  So, the study of “mind” is only a part of psychology, which is itself a branch of the philosophy of nature.

Now when the early moderns chucked out the Aristotelian-Scholastic philosophy of nature, “psychology” was radically transformed.  Gone was the idea that there is an absolute difference in kind -- in particular, a difference in substantial forms and immanent teleological properties -- rather than a difference in degree, between the inorganic and the organic, and between different sorts of inorganic phenomena and different sorts of organic phenomena.  The natural world would come to be reconceived as a vast sea of matter -- “matter” now understood in corpuscularian, atomist, or plenum theoretic terms, and more generally in mathematical terms -- on which tables and chairs, rocks and trees, dogs, cats, and human bodies were, in effect, all just so many waves, the differences between them relatively superficial.  No longer thought of as the substantial form of a living thing, the soul was shrunk down to Descartes’ res cogitans, and the sequel was the modern idea that “psychology” is essentially the study of the mind.  

Now to effect this re-conception of matter, the moderns had to deny that color, odor, sound, taste, heat, cold and sensory qualities in general really existed in the material world in the way common sense supposes they do.  Therein lay the origin of the “qualia problem” -- the problem of explaining exactly how, if these qualities are not really in matter, they are related to the brain, which is one material object among others.  Immanent final causes were also removed from the material world.  And therein lay the origin of the “problem of intentionality” as that is understood in modern philosophy -- the problem of explaining how, if nothing in the material world is inherently “directed toward” anything else as to an end or goal, the directedness of thought relates to the brain.  Features that had once been regarded as inherent to material phenomena in general were suddenly relocated into the mind, which made the mind seem a bizarre exception to what natural science had to say about the rest of nature.  The “philosophy of mind” arose as the discipline concerned with solving this problem.  Cartesian- and property-dualist “solutions” face the interaction problem and the specter of epiphenomenalism; materialist “solutions” tend toward an incoherent eliminativism.  From the Aristotelian-Scholastic point of view, the whole problem -- and by implication the discipline that arose to deal with it -- rests on a mistake.  (See chapter 4 of Aquinas and chapters 5 and 6 of The Last Superstition for more detailed treatment of this subject.)

A friend once asked me why I thought there was in modern philosophy no parallel sub-discipline called the “Philosophy of matter.”  A very good question.  The answer, I think, is that a great many modern philosophers have uncritically swallowed the idea that physical science tells us everything we need to know about matter and that mind alone is problematic, so that a “philosophy of mind” is needed in a way that a “philosophy of matter” is not.  Many, but not all.  Bertrand Russell and contemporary philosophers influenced by him (Michael Lockwood, Grover Maxwell, David Chalmers, Galen Strawson, and others) have emphasized that physics does not in fact give us the intrinsic nature of matter, but only its structure.  Idealists, panpsychists, process philosophers, and neutral monists have offered different accounts of what this intrinsic nature is.  They do not agree with the Aristotelian-Scholastic philosopher about the solution, but at least they recognize the problem.  And there really is no good reason why matter, as the moderns tend to think of it, should be considered any less problematic than mind; indeed, as these various non-materialist modern philosophers tend to realize, it is more problematic.  (It was by reading Russell and Lockwood -- neither of whom is a religious apologist -- that I came to see, while I was in graduate school and still an atheist, just how philosophically problematic the modern conception of matter really is, and how superficial is the thinking of most contemporary materialists.)

It is arguable that even the “Philosophy of religion,” as that discipline is understood today, is an artifact of the moderns’ abandonment of the philosophy of nature.  For the Aristotelian-Scholastic tradition, the theory of act and potency, when worked out, leads us to the existence of a cause of change that is pure actuality, which is the philosophical core of the Aristotelian conception of God.  Other arguments in the philosophy of nature and in metaphysics lead in the same direction.  (See chapter 3 of Aquinas and my ACPQ article “Existential Inertia and the Five Ways” for more on that subject.)  The upshot is a body of knowledge that constitutes a “science” (in the Aristotelian sense) of its own, namely natural theology.

But as I noted in my earlier post, the main arguments of traditional natural theology were radically transformed (and indeed stripped of their force) as a result of the abandonment of the philosophy of nature.  In particular, they were retooled either as arguments of the Leibnizian rationalist metaphysical sort or as quasi-scientific empirical hypotheses of the Paleyan sort, and thereby made subject to stock objections often regarded as fatal, but in fact irrelevant to the older Aristotelian-Thomistic theistic arguments.  With the virtual disappearance of the philosophy of nature and the deflation of metaphysics, natural theology as a body of knowledge in its own right also disappeared.  In its place came the “Philosophy of religion,” a handful of stand-alone philosophical curiosities rather than (as Scholastic natural theology had been) a vast and systematic body of thought.  The dismissal of grotesque caricatures of the Five Ways would become the order of the day as Aristotelian metaphysics and philosophy of nature, apart from which the arguments cannot be understood, were forgotten.  The Platonic-Augustinian background to Anselm’s ontological argument would also be routinely ignored.  In general, the arguments of classical and medieval authors would be crudely assimilated to those of modern writers like Leibniz, Descartes, and Paley, and thereby misinterpreted either as exercises in rationalist metaphysics grounded in “conceptual analysis,” or as “god of the gaps”-style empirical hypothesis formation.  

There’s more to the story than that, of course.  But that story, like the story of modern philosophy in general, simply cannot be understood unless one understands the role that the philosophy of nature played in ancient and medieval thought, and the gap that was left when it was abandoned.