Introduction

As a worldview, naturalism depends on a set of cognitive commitments from which flow certain propositions about reality and human nature.  These propositions in turn might have implications for how we live, for social policy, and for human flourishing.   But the presuppositions, basis, and implications of naturalism are not uncontested, and indeed there’s considerable debate about them among naturalists themselves.

In championing a worldview, we are necessarily forced to defend some version of its presuppositions and implications, and to do this we must engage in argument and analysis.  The question is, how deep are we obligated to go in this defense?  How many objections, replies, counterarguments, and technicalities must we take on before we’re satisfied that we’ve got a tenable worldview?  What are our philosophical responsibilities, and how do we balance them with the practical matter of applying our beliefs to our lives and culture?

There’s no obviously right answer to this question, except that as we encounter telling objections to our comfortable and perhaps comforting beliefs, we should feel an obligation to address them.  But there’s no clear stopping point at which we can declare that the inquiry is over, that our view is secure from doubt.  It’s just at some point we declare to ourselves that at least for the time being we’re provisionally satisfied that our defense is good enough, that there’s nothing obviously better as a worldview lurking in the neighborhood.  This stopping point will be different for different individuals, depending partially on their stomach and talent for philosophical analysis.

Although one version of the cognitive commitments and implications of naturalism is defended to a limited extent at Naturalism.Org, the question of naturalism’s philosophical grounding and direction remains, as suggested above, perennially open. A recent inquiry about such matters provoked a friendly exchange between two philosophers, Richard Carrier and David Macarthur, each with a recent book to their credit. The exchange is presented below, verbatim, as a not necessarily representative but nonetheless instructive slice of the debate about some issues involved in naturalism, including causality, physicalism, reductionism, normativity, and conceptualism. Some will find it overly technical and perhaps beside the point, especially for the purpose of drawing practical conclusions about how we should live in the light of naturalism. But others will think it of considerable importance – about things that should be decided if we’re to make an adequate defense of naturalism, or present it as a coherent philosophy and worldview. Either way, this exchange explores some interesting philosophical territory, and it illustrates a few of the disagreements that surface when basic questions are posed about naturalism, as well as some commonalities.

Note on explanatory transparency

Regarding commonalities, what seems to be common ground between Carrier and Macarthur, and which therefore might be considered fundamental to naturalism, is simply a commitment to explanatory transparency.  This commitment is common to both philosophy and science, which may explain why, as Macarthur puts it, naturalism holds to “the continuity of philosophical and scientific inquiry.”  Explanatory transparency, in light of “the totality of observations” (Carrier), is perhaps the summum bonum of the rational and empirical inquiry that naturalism takes as its epistemology.   This epistemic commitment is prior to any ontological or metaphysical conclusion, whether it be the status of causality, reductionism, physicalism, or normativity, which Carrier and Macarthur disagree about below. 

Oppositely, supernaturalism can perhaps be understood as entailing explanatory opacity: having prior metaphysical or ontological commitments (e.g. to god, the soul, contra-causal freedom) blocks access to transparent, rational, evidence-based explanations.  So, perhaps it’s the inversion of epistemic and ontological priorities that most basically distinguishes naturalism from supernaturalism.

My sincere thanks to Richard Carrier and David Macarthur, and to Gabriel Mihalache of Romania for getting the ball rolling.

TWC, 8/2005

Mihalache poses some interesting questions about naturalism

August 1, 2005 –  Gabriel Mihalache poses some interesting questions about naturalism.

Hello!

My name is Gabriel Mihalache and I'm from Romania. I've been reading your material on the naturalism.org website and, first of all, I wanted to tell you how much I appreciate your contribution to the debate, and secondly to suggest some topics that I'd find helpful if they'd get more coverage (for your Philosophy page, I imagine).

~  Causality: Can it be proved? Can we know it? How would we know when we know it? Is it a priori?

~  Since scientific results are provisional in nature, in a sense, the causality of contemporary scientific theories is also provisional.  Even if we assume that some core causality is true, how would we know we got to that core? (I'm thinking along the lines of Kant's phenomenon/noumenal distinction.)

~  I'd like to see more arguments related to the extraction of an "ought" out of the "is" in the context of your politics claims. Can we still think in terms of "oughts" in naturalism? And if there are no "oughts", how would one build political arguments? What does it mean that "we ought to do this and that" considering that there's no authentic choice? How can one expect to influence world events if one cannot influence himself? (I admit that I use "influence" here in the strongest sense possible, but that's only because we have that concept, false as it might prove, or not.)

~  The problem of conceptualism: considering that the Universe is a soup of varied base particles and energies (whatever they might be), conceptualism holds that out understanding of the world, even of sensory input, is shaped by our conceptual system. The reason why I see a desk and not spots of color (rays of light entering my eyeball) is because I have a concept of desk which "shaped" my vision. (I wanted to get into a bit of detail here because "conceptualism" is used by many people in different ways.)

Anyway... considering that, according to conceptualism, we can only see the world through our conceptual "glasses" we could claim that: 1) causality is just a concept we use to give meaning/interpret some phenomena; 2) we could "see" this soup of matter and energy otherwise; 3) one cannot step outside of one's own conceptual system and "see" differently.

My question is this... can you provide an argument for the absoluteness of causality, even if conceptualism is true of humans? And if not, does that mean that naturalism is a form of ontological realism? ... I'm interested in identifying which ontological points of view are compatible with naturalism.  (The same discussion makes sense for epistemology.)

Sincerely yours,
Gabriel Mihalache

Romania

Clark Replies to Mihalache, recommending books by Richard Carrier and David Macarthur

August 1, 2005 –  Tom Clark responds to Gabriel by recommending books by Richard Carrier and David Macarthur.

Hi Gabriel,

Many thanks for writing and I certainly appreciate all your good suggestions and questions.  The philosophical basis and implications of naturalism are of considerable interest to me, but I'm split between such interest and making naturalism known as a viable worldview in the marketplace of belief, a worldview with many important personal and social implications.  In order to do the latter, one has to work on the assumption that naturalism is more or less valid, based on a commitment to science as one's preferred epistemology.  So fleshing out a detailed philosophical defense of naturalism, although an important project, is somewhat on the back burner for me.  Richard Carrier, in his book Sense and Goodness Without God: A Defense of Metaphysical Naturalism, has done valuable work on this which I recommend to your attention.  There's also a book of philosophical essays just out, Naturalism In Question, that might be of interest to you.  I will keep your questions in mind when developing future materials for the Philosophy page.

best regards,

Tom Clark

David Macarthur responds to Mihalache

August 2, 2005 – David Macarthur responds to Gabriel.

Dear Tom,

Thanks for forwarding Gabriel's email. Gabriel asks several important questions which I cannot hope to respond to fully. But I am happy to say a few things in reply. In Naturalism in Question (HUP, 2004) Mario De Caro and I understood "naturalism" (better: "scientific naturalism"), as used by most Anglo-American philosophers, to indicate a commitment to one or both of two core themes: 1) an ontological theme: a commitment to an exclusively scientific conception of nature; and 2) a methodological (or epistemological) theme: the continuity of philosophical and scientific inquiry. Many philosophers assume that naturalism gives pride of place to some conception of "the causal order of nature". This seems to me misguided. For a start, it mistakenly presupposes that all sciences are in the business of discovering causal laws. But there are biological and social sciences that do not fit this understanding. Moreover, it is a common misconception to think that naturalism is committed physicalism (or materialism).

But what naturalism is really committed to -- at least prima facie -- is ontological pluralism i.e. belief in all the various entities, objects and events that figure in all of the irreducibly different levels of scientific explanation from physics, chemistry and biology to geology, physiology, economics, sociology, oceanography, acoustics, aerodynamics, paleontology and so on and on. And included in this pluralism is a plurality of causal explanations at many different levels of description e.g. there are causal explanations at the atomic level, at the level of neurotransmitters and at the intentional level of beliefs and desires and so on. Naturalists are committed to the worldview of the various sciences but not to there being, even in principle, a reduction of all sciences to physics or a reduction of all causal explanations to physical causes. In so far as the naturalist admits a plurality of sciences with different irreducible levels of scientific explanation (many of which are causal) then there will be a plurality of ontological commitments at each level including a plurality of causal explanations – which is to say that, for the consistent non-reductive naturalist, the physical and the causal laws of physics do not exhaust the things or causes that there are. For more discussion of causal pluralism see the work of Peter Menzies.

Causes are natural phenomena that are discovered empirically. Rational relations are a priori but not causal ones. Of course, a naturalist will be happy with a pragmatist or broadly fallibilist conception of epistemology which is, indeed, provisional.

As for "oughts" or the general phenomena of normativity: here, too, I think there is a large misconception. Many philosophers seem to think that there is some deep tension between naturalism and normativity. But the tension is really between physicalism and normativity. If the physical is all that there is then there is no place in nature for normative phenomena like reasons, meanings and values. But, as I said above, naturalists are committed to ontological and causal pluralism, not to physicalism or merely physical causes. A naturalist accepts the claim that scientific ontology exhausts total ontology, so the crucial question is whether there are sciences that recognize normative phenomena in their best explanations. And surely there are!! Such things as values, meanings and reasons do indeed figure in such sciences as anthropology, intentional psychology and economics. For instance, an anthropologist might be concerned with the meaning or significance of certain rituals, a psychologist with one’s reasons for action under certain circumstances (which itself may involve responsiveness to ethical values), and an economist may be concerned with the notion of living a valuable life, one including such things as self-respect.

Re conceptualism: this is no part of naturalism although it might be consistent with it.

On causation as absolute or perspectival: again naturalism does not involve a commitment either way. But the very fact that the laws of physics are symmetrical and causation is an asymmetrical relation (involving the arrow of time) strongly suggests that causal perspectivism is true, namely, the view that causation is tied to the human perspective and our explanatory interests. For more discussion about this see the work of Huw Price.

best regards,

Dr. David Macarthur
Lecturer & PG Research Co-ordinator
The Department of Philosophy
Main Quad, A14
The University of Sydney
N.S.W.  2006,  Australia

Richard Carrier responds to Mihalache

August 2, 2005 – Richard Carrier responds to Gabriel.

Gabriel,

For rigorous philosophical foundations of naturalism, unbeatable so far is Mario Bunge's eight-volume work Treatise on Basic Philosophy.  Despite the ambiguous title, this is an eight volume defense of metaphysical naturalism in extensively formal detail--in fact, apart from my book, this multivolume set is the only systematically complete defense of naturalism as a worldview yet in existence. Given your particular interest in causality, Bunge also wrote Causality and Modern Science (1979) from a naturalist perspective, although I don't know what position(s) he defends there, and he may have substantially revised them for his discussion of the philosophy of causality in his new 2-volume textbook Philosophy of Science (1998), which addresses countless issues of philosophical foundations, all from a naturalist perspective (hence I recommend it).

My own book, Sense and Goodness Without God: A Defense of Metaphysical Naturalism, does not address the question "What is causation?" in specific detail, though one can infer from what I do say there that I start from a metaphysical (ontological) theory (that causation is what happens when objects with certain geometric shapes collide with each other, according to the deductive findings of Archimedes and others) and then I let scientists test that theory against the evidence. Thus, imo, a materialist theory of causation is a "best explanation" of observed phenomenon, not the only possible explanation, and it is a theory which is confirmed or falsified by observations, not an observation in and of itself. I think this is in fact how scientists view the matter, regardless of what philosophers say. Even if scientists disagree as to what causation consists of, I think they all agree that causation is not an a priori fact but an empirical theory that is at present the best explanation of what we observe (which means  the theory of causation can be and has been revised as more observations are made).

Second, provisional knowledge is not the same thing as provisional fact. That our belief that causation exists and operates a certain way is provisional does not mean that causation itself is provisional. There is a categorical difference between epistemic probability (the probability that what we believe is true) and physical probability (the probability that something will actually happen, e.g. that atom A colliding with atom B will cause B to move in manner C). These two probabilities are not the same thing, so reducing one doesn't necessarily reduce the other. In terms of how we deal with uncertainty, I discuss this in some detail in my book's section on epistemology.  In short: we say "we believe naturalism is probably true" in the sense that we assign a high epistemic probability to naturalism as a theory of existence.

Third, in my book I devote considerable space and detail to proving that there is only one logically coherent way to get an "ought" from an "is," and in fact I claim to demonstrate that there are universally true imperative propositions. So if you want that foundation, you certainly should read my book (Sense and Goodness without God). Mine isn't the only naturalist point of view on the matter, but to my knowledge (imo) mine is the only fully-articulated view that makes any sense of imperative language in any worldview, whether naturalist or supernaturalist.

Fourth, I refute the conceptualist charge (made by Michael Rea) in an article online, and Naturalism.org already links to my list of online work on naturalism, but you can find it here (the Rea piece is on that list). Perhaps if Tom has any sections devoted to the issues any of my online essays address, he may link to them specifically in those sections, but that's up to him and his plan for his site. However, take care not to conflate ontological conceptualism (OC) with epistemic conceptualism (EC). OC holds that, e.g., there is no real causation, that this only exists as a human concept. This is the absurd view that I attack in my critique of Rea.  It is simply not an adequate explanation of what we observe (e.g. not-OC is a better explanation of what we observe, even if OC remains a possible explanation). But EC holds that though there is a real "thing" going on that produces what we call causation, the way we perceive and understand that "thing" is constrained to a certain extent by our concepts and conceptual models. And these can be human constructed and biologically constructed--the former include scientific theories, e.g. models of the atom, and the later include neurophysical systems of perception, e.g. the fact that we see steady barrages of photons of a particular range of frequencies striking our eyes as a continuous patch of the color green. EC is without doubt true, and is a problem scientists have to constantly devise tactics to overcome, and I discuss examples of the EC nature of our existence (though I do not identify these as an EC issue) in my book in various separate sections on aesthetics and the ontology of knowledge.

In other words, it is certainly true (and has to a modest degree been scientifically proven) that "we can only see the world through our conceptual 'glasses'" but this does not entail, and in fact given the totality of observations made it doesn't even strongly imply, that, e.g., "causality is just a concept we use to give meaning/interpret some phenomena." Causality certainly is a concept that we do use to give meaning to or interpret some phenomena, but it is not just a concept, but is a theory that seeks to explain what we observe and so far explains what we observe better than any other theory known.

Likewise, it is not completely the case that "one cannot step outside of one's own conceptual system and 'see' differently." We can in fact put on almost any set of glasses we can think of, and therefore we can indeed see things differently, and human beings do this so often that the phenomenon of "changing perspective" has been studied in psychology, neuroscience, game & puzzle theory, etc. The only limitations regarding "seeing things differently" are neurophysical: e.g. we can't choose to see green-frequency photons in any other way than as a patch of the color green. But though this is all we can ever see, this does not prevent us from understanding that the green patch we see is a mental construct informing us of a more complex physical fact (that there is a constant barrage of photons of a particular frequency impacting the eyes). So the truth of EC does not prevent us from identifying true physical facts, nor do the inherent limitations of all conceptual systems necessarily prevent us from understanding the nature of our underlying reality.

Be well.

Richard C. Carrier, M.Phil.
Columbia University
www.columbia.edu/~rcc20

Carrier responds to Macarthur

August 3, 2005 – Carrier responds to Macarthur.

Just to add my commentary to some pieces of what David wrote:

> It is a common misconception to think that naturalism is committed
> physicalism (or materialism).

This is an important point: I am a physicalist and defend physicalist naturalism, but as I explain in my book, that is not the only variety of naturalism there is. My answers thus should be taken as those of a naturalist who is a physicalist, and not a representative of all naturalists. The same goes for what follows.

> But what naturalism is really committed to -- at least prima facie --
> is ontological pluralism i.e. belief in all the various entities,
> objects and events that figure in all of the irreducibly different
> levels of scientific explanation from physics, chemistry and biology
> to geology, physiology, economics, sociology, oceanography, acoustics,
> aerodynamics, paleontology and so on and on.

I don't believe naturalism is necessarily committed to this view.  If it is theoretically possible to reduce all entities to a single substance or activity, for example, then what we have (given the list above) could be explanatory pluralism, not ontological pluralism. At any rate, though naturalism doesn't entail this, I believe all phenomena can be reduced to matter-energy in space-time, and whether that constitutes a plurality of ontological species is more a matter of semantics to me.

> Naturalists are committed to the worldview of the various sciences but
> not to there being, even in principle, a reduction of all sciences to
> physics or a reduction of all causal explanations to physical causes.

Correct: naturalists are not committed to this view, but those who do believe all sciences reduce to physics, etc., are still naturalists (called physicalists). I discuss the nature and problems of different kinds of reduction in my book.

However, I think we need to be careful with statements like "naturalists are committed to the worldview of the various sciences," since that presumes a priori that science cannot discover the supernatural, and I do not believe that is a valid assumption.   The methods of science make no mention of a natural-supernatural distinction, for example, and I see no reason why science cannot discover supernatural entities the same way it does atoms or forces of any other kind.  If, instead, the word "naturalism" is taken to mean simply "whatever science discovers" then what you are espousing is a methodology (i.e. the rejection of claims not supported by the sciences), not an ontological commitment, since ontologically, science can discover almost anything; hence, with sufficient evidence nearly all worldviews can become scientific worldviews, rendering the word "naturalism" in such a sense all but meaningless.

Furthermore, in actual practice, this is not how the word naturalism is used by actual naturalists today (Quine, for example, is not at all representative anymore), as I demonstrate in my critique of Rea.

> As for "oughts" or the general phenomena of normativity: here, too, I
> think there is a large misconception. Many philosophers seem to think
> that there is some deep tension between naturalism and normativity.
> But the tension is really between physicalism and normativity. If the
> physical is all that there is then there is no place in nature for
> normative phenomena like reasons, meanings and values.

This is not true, and I refute the notion extensively in my book (Sense and Goodness without God). Reasons, meanings and values can exist on physicalism, as can normative principles. As David already hinted at, many of the sciences entail normative propositions.  Medicine discovers scientifically how we ought to treat patients in order to cure them, engineering discovers scientifically how we ought to build bridges in order to survive earthquakes, etc., and for these findings to be true, nothing need be the case except the relevant physical facts.

Morality is simply the proposal that there is an overriding end shared by all people (universalism) or within distinguishable groups (relativism), and just like an end in medicine (curing patients) or engineering (surviving earthquakes), this "moral end" would entail normative propositions (either for everyone, if universalism is true, or for categorized groups, if relativism is true).  Since "moral end" is already defined by all cultures as an end that supercedes all other ends, then it is true by definition that moral ends exist, because everyone will have some end that for them supercedes all others in importance. And if we recognize that a person may think differently who is fully informed of all the relevant true facts and reasoning coherently from those facts, true moral facts would consist of what a person in this state would acknowledge as true, rather than what a person thinks is true at any given time, which establishes moral facts as physical facts in the same way as for medicine and engineering.

Of course, one might raise many objections and questions to what I just said, but my book deals with all of that in detail--I am also submitting a paper for peer review that does the same, with greater precision. For now, it should at least be recognized that physicalism does not necessarily entail the absence of true "ought" statements.

> On causation as absolute or perspectival: again naturalism does not
> involve a commitment either way.

This is again correct and worth repeating: my response on this point reflects the viewpoint of one particular naturalist worldview (i.e. mine) and does not necessarily hold for all naturalists, many of whom disagree with me.

David, thanks for the comments!  We disagree on some things, but I found your email to be very well written and informative.

Be well.

Richard C. Carrier, M.Phil.
Columbia University
http://www.richardcarrier.info

Macarthur replies to Carrier

August 8, 2005 – Macarthur replies to Carrier.

Since there is interest in these matters I thought I might say something (very brief) in reply to Richard whom I want to thank for his thoughtful remarks.

Macarthur original:  But what naturalism is really committed to -- at least prima facie -- is ontological pluralism i.e. belief in all the various entities, objects and events that figure in all of the irreducibly different levels of scientific explanation from physics, chemistry and biology to geology, physiology, economics, sociology, oceanography, acoustics, aerodynamics, paleontology and so on and on.

Carrier reply: I don't believe naturalism is necessarily committed to this view.  If it is theoretically possible to reduce all entities to a single substance or activity, for example, then what we have (given the list above) could be explanatory pluralism, not ontological pluralism. At any rate, though naturalism doesn't entail this, I believe all phenomena can be reduced to matter-energy in space-time, and whether that constitutes a plurality of ontological species is more a matter of semantics to me.

 Macarthur rejoinder:  This is the crucial issue: whether there is a reduction of higher level sciences to the so-called "hard sciences", or perhaps only physics. A great deal of work on this topic has been done and the growing consensus is that reduction is out of the question.  That's why so many now think of physicalism in a much weaker sense than Richard holds, namely, the global supervenience of non-physical properties on physical properties. Weak physicalism is thought of as a non-reductive position because many believe that supervenience does not entail reduction.  Note that weak physicalism is compatible with ontological pluralism!  So, given the failure of large-scale physicalist reductionism, naturalism is committed to both explanatory pluralism and (as a consequence of that) ontological pluralism.  Richard is a hard-headed physicalist of the Armstrong school but belief in such strong physicalism (and its presupposition of ontological monism) is paradoxically supernatural, as Dupré argues in Naturalism in Question.

Macarthur original:  Naturalists are committed to the worldview of the various sciences but not to there being, even in principle, a reduction of all sciences to physics or a reduction of all causal explanations to physical causes.

Carrier reply:  Correct: naturalists are not committed to this view, but those who do believe all sciences reduce to physics, etc., are still naturalists (called physicalists). I discuss the nature and problems of different kinds of reduction in my book.

However, I think we need to be careful with statements like "naturalists are committed to the worldview of the various sciences," since that presumes a priori that science cannot discover the supernatural, and I do not believe that is a valid assumption (the methods of science make no mention of a natural-supernatural distinction, for example, and I see no reason why science cannot discover supernatural entities the same way it does atoms or forces of any other kind). If, instead, the word "naturalism" is taken to mean simply "whatever science discovers" then what you are espousing is a methodology (i.e., the rejection of claims not supported by the sciences), not an ontological commitment, since ontologically, science can discover almost anything; hence with sufficient evidence nearly all worldviews can become scientific worldviews, rendering the word "naturalism" in such a sense all but meaningless.

Furthermore, in actual practice, this is not how the word naturalism is used by actual naturalists today (Quine, for example, is not at all representative anymore).

Macarthur rejoinder:  I agree with much of this but saying that naturalism is committed to the worldview of the various sciences does not prejudge what worldview that is.  For example, the aspect of the world revealed by contemporary physics looks pretty "supernatural" from a  common sense perspective.  Science might indeed reveal that the world operates according to "weird" laws etc.  But as a scientific discovery we distinguish such weirdness from the supernatural which is, by definition, the subject-matter of no science. Naturalism is committed to the methodologies of the sciences and to the objects, etc. that figure ineliminably in its best explanations.  So it’s got both methodological and ontological implications.  Indeed, without a scientific ontology the so-called naturalization projects of contemporary metaphysics -- which explain the function or role of certain discourses given a certain conception of "the natural facts" -- would not make sense.

Also:  Quine is indeed a naturalist, but, like Richard, he is also a physicalist. Quine's influence on contemporary naturalism has been enormous. But I agree with Richard to this extent: there is a great deal that might be said in criticism of Quine's understanding of the two basic themes of naturalism. A more plausible and pluralistic version of scientific naturalism can be found in the pragmatist tradition e.g. Dewey, Sellars.

Macarthur original: As for "oughts" or the general phenomena of normativity: here, too, I think there is a large misconception. Many philosophers seem to think that there is some deep tension between naturalism and normativity. But the tension is really between physicalism and normativity. If the physical is all that there is then there is no place in nature for normative phenomena like reasons, meanings and values.

Carrier reply:  This is not true, and I refute the notion extensively in my book (Sense and Goodness without God). Reasons, meanings and values can exist on physicalism, as can normative principles. As David already hinted at, many of the sciences entail normative propositions.  Medicine discovers scientifically how we ought to treat patients in order to cure them, engineering discovers scientifically how we ought to build bridges in order to survive earthquakes, etc., and for these findings to be true, nothing need be the case except the relevant physical facts.

Morality is simply the proposal that there is an overriding end shared by all people (universalism) or within distinguishable groups (relativism), and just like an end in medicine (curing patients) or engineering (surviving earthquakes), this "moral end" would entail normative propositions (either for everyone, if universalism is true, or for categorized groups, if relativism is true).  Since "moral end" is already defined by all cultures as an end that supercedes all other ends, then it is true by definition that moral ends exist, because everyone will have some end that for them supercedes all others in importance. And if we recognize that a person may think differently who is fully informed of all the relevant true facts and reasoning coherently from those facts, true moral facts would consist of what a person in this state would acknowledge as true, rather than what a person thinks is true at any given time, which establishes moral facts as physical facts in the same way as for medicine and engineering.

Of course, one might raise many objections and questions to what I just said, but my book deals with all of that in detail--I am also submitting a paper for peer review that does the same, with greater precision. For now, it should at least be recognized that physicalism does not necessarily entail the absence of true "ought" statements.

Macarthur rejoinder.  I cannot reply to all of this here. But Richard makes the standard Quinean move of only allowing for hypothetical imperatives given a certain set of (natural) ends. Of course normativity in that weak sense is compatible with strong physicalism. But the normative phenomena I was speaking about -- reasons, meanings and values --  cannot be exhaustively characterized in such terms. Consider reasons. We can reason about the appropriateness of ends, for example, and not just in terms of further taken-for-granted ends.  For any set of ends we can step back in deliberation and wonder about their rational credentials.  Such reasoning simply presupposes that we are responsive to rational "oughts" that cannot be characterized in hypothetical terms.  For more discussion see McDowell "Are Moral Requirements Hypothetical Imperatives?"
 
Dr. David Macarthur
Lecturer & PG Research Co-ordinator
The Department of Philosophy
Main Quad, A14
The University of Sydney
N.S.W.  2006,  Australia