Dianelos Georgoudis replied at length to my earlier posting on metaphysical naturalism and consciousness, and I would like to continue the conversation. I characterize metaphysical naturalists as committed to the causal closure of the natural universe, i.e., to the claim that natural phenomena, to the extent that they are caused (and not, say, random or brute facts), are caused by natural entities, forces, processes, etc. In other words, to parody the slogan about Las Vegas, what causes things in the universe, stays in the universe.
Dianelos comments:

“I have two observations with the idea that according to MN the universe is a causally closed system. I agree that there is overwhelming evidence that all physical phenomena can be explained using only impersonal naturalistic entities, causes, and mechanisms – specifically excluding any supernatural personal entities such as gods, ghosts and souls. My first observation is that physical phenomena are by far not all the data we have, for there is also our subjective experience of life. My second observation is that the fact that the universe appears to be causally closed does not imply that it is.”

I am puzzled by the first observation because it appears simply to beg the question against MN. Subjective experience appears to me to be a natural phenomenon. Thinking, feeling, imagining, willing, and so forth seem to be activities (voluntary or involuntary) of physical beings accomplished via the functionality of their bodily organs, like breathing or exercising. The phenomena of subjective experience therefore seem to me no more mysterious or otherworldly than tap dancing (less so, if you have two left feet like me). People dance with some body parts, digest with others, and do predicate logic proofs with yet others. To be a counterexample to MN, we would need to experience consciousness in a disembodied context. If Marley’s ghost appeared to me tonight to warn me of the consequences of my sins, and I could not explain the apparition away, as Scrooge tried to do, as the effect of a bit of underdone potato, then, yes, I would regard such a visitation as a counterexample to MN. Clearly, though, all such purported counterexamples—encounters with ghosts or gods—are highly controversial and would not be accepted by naturalists.

The second observation is surely correct. The fact that anything appears to be so does not entail that it actually is so (except maybe for famously “incorrigible” phenomena like seeming to have a headache). Still, it seems plain good sense, even in metaphysics, to say that if something manifestly seems to be so, then we should tentatively regard it as so until and unless we have reason to think otherwise. So, my intention expressed in my earlier post to put the burden of proof onto non-naturalists seems to be justified. How heavy should this burden be? Well, nothing succeeds like success, and methodological naturalism seems an excellent candidate for the most successful heuristic assumption of all time. We assume that natural things have natural causes, we doggedly look for those natural causes, and we keep finding them—broader and deeper ones all the time.

Vitalism was the last outpost of supernaturalism in respectable science, and it expired in the early 20th Century. Prior to vitalism’s last gasp, many supernatural accounts had fallen victim to the realization expressed in Laplace’s quip to Napoleon, “I have no need of that hypothesis.” The fecundity of naturalistic theories and the poverty and failure of supernatural ones led scientists, even pious ones, to stipulate, well before Darwin, that science should focus on “secondary” (i.e., natural) causes and leave discussion of the primary cause (i.e., God) to theologians. In short, the naturalistic research program has succeeded spectacularly and the supernaturalistic one has gone extinct, despite the desperate efforts of “intelligent design” theorists to re-animate the corpse. Generalizing upon the spectacular success of the naturalistic heuristic, it appears that natural causes are sufficient for all caused phenomena in the natural world. That this is the plain appearance of things, requiring proof otherwise, was already obvious to Thomas Aquinas in the 13th Century: “Now it seems that everything in the world stems from sources other than God, since the products of nature have their source in nature; deliberate effects can be traced back to human reason or will as their source. There is no need then to assume that God exists (Summa Theologiae, I, q. 2, art. 3).”

As Dianelos notes, I am deeply suspicious of efforts to elucidate the nature of ultimate reality, for many of the reasons that Kant gave. However, since ultimate questions are inevitably so fascinating to us, and since a rigorous agnosticism is very hard to maintain, I think it is OK if we try to come to the most reasonable conclusions we can, always marking that part of our epistemic maps with “here be dragons.”

So, which is the more reasonable postulate, that reality is ultimately natural or supernatural? As Dianelos puts it:

“Does reality ultimately consist of entities that act and are acted upon in accordance with regular, impersonal, and universal laws (as naturalism has it), or does reality ultimately consist of entities that act and are acted upon in accordance with free, personal, and universal will (as theism has it)? Or alternatively: Is knowledge about reality ultimately based on the former premise or on the latter premise? Are the most comprehensive explanations ultimately based on mechanical causality or on agent causality?”

I opt for the former, as I say, mostly by default, i.e. because of the utter lack of any reason to postulate any other kind of thing. I know that natural things exit; indeed, I know that the natural sciences have had enormous success explaining natural things in natural terms. I am unaware of any phenomena that would be better explained in supernatural terms. Natural causes appear sufficient. In fact, the supernaturalistic explanations I am familiar with seem to be woefully devoid of explanatory efficacy, certainly vis-à-vis accepted naturalistic ones. Supernatural accounts are pretty consistent: their modus operandi is to create a mystery where there is no mystery, and then to invoke some putative supernatural entity, like God or souls, that appears tailor-made to provide a pseudo-explanation for the pseudo-mystery. The “explanation” provided then leaves me even more puzzled than I was before. Inevitably, such “explanations” work by postulating untestable hypotheses invoking inscrutable entities which are asserted to wield occult powers to produce effects in some unknowable way. So, if asked to place my bets about what substantial reality consists of, I say the entities that constitute the space/time universe.

Dianelos says:

“By the claim that ‘consciousness is a scientifically unnecessary concept’ (or, similarly, that ‘experience is a scientifically unnecessary concept’) I mean that the best explanation of physical phenomena need not make use of such concepts, the same way that the best explanation of fire need not make use of the phlogiston.”

This is a bit confusing. We don’t explain fire in terms of phlogiston, because we know that the phlogiston theory is false. An eliminative materialist might compare consciousness to phlogiston, meaning that they are both discredited notions, but I know that Dianelos does not intend to do so in that sense. He continues:

“Conversely we believe that atoms exist in as far as the best explanation of phenomena (of Brownian motion say) requires them. Similarly we know that a monkey’s behavior is best explained by the electrochemical processes in its brain. Now one can name a particular pattern of neuron firings in a monkey’s brain ‘disappointed’ (or say that the behavior caused by such neuron

firings evidences that the monkey is disappointed) but such naming conventions add nothing to the explanation; one might as well name the same pattern P342. Indeed, it’s easy enough to anthropomorphize phenomena in contexts where no consciousness is present.”

But there is no one “best” way to explain the monkey’s behavior. It depends on the kind of question we are asking and the kinds of observations we are seeking to explain. The question that Tinklepaugh was asking in the experiment referred to in the earlier post was why the monkey behaved the particular way that it did when it turned over the cup and found lettuce rather than banana. The behavior is readily explicable upon the postulation of mental states—the mental representation of banana under the cup and a consequent experience of disappointment upon finding lettuce instead—and not explicable, or certainly not readily so, in terms of unconscious stimulus-response processes. So we appear to have a clear case of inference to the best explanation, which, in this case, involves the postulation of conscious states. There is no basis for regarding such inference as anthropomorphic unless we assume that only humans are capable of having conscious states.

But is the postulation of consciousness necessary here? Couldn’t we, in principle, explain the monkey’s behavior merely by detailing its physiological antecedents? Sure we could, just as we could explain any piece of human behavior in precisely the same way—hence the philosophical problem of other minds. But if we hold that conscious processes (e.g., thinking, willing, feeling) are fully realized in physical processes (patterns of neuronal firings, etc.), then explanations in terms of consciousness are fully compatible with, and, in fact subsumed by, physiological explanations, which are in turn subsumed by explanations in terms of chemistry and physics. However, the fact that explanations in terms of A’s subsume explanations in terms of B’s does not mean that B’s do not exist or are not useful, indeed, indispensable, at certain levels of explanation.

Why, at the end of the “Gloria” section of Beethoven’s Missa Solemnis did Beethoven make the orchestra suddenly go silent while the chorus shouts out the final “Gloria!” into the empty air? Suppose we ask just why Beethoven composed it that way. A complete description of all the relevant states of Beethoven’s brain, qua brain states, as he was composing the end of the “Gloria” would, of course, leave us dissatisfied. We want to know why it seemed aesthetically right to him to suddenly yank the orchestral accompaniment out from under the chorus. We would like to know what he was feeling, i.e., what his musical intuitions were telling him. Surely he realized that the effect would be breathtaking, as indeed it is. But if Beethoven’s artistic intuitions were fully realized in his brain states, then even the creativity of a Beethoven can, in principle, be subsumed under physiological explanation (without thereby obviating explanations in terms of aesthetic intuitions).

Dianelos continues:

“…my argument is not about why or how a material system becomes conscious, nor about the explanatory gap between scientific and experiential knowledge; these are distinct problems on their own right. I simply observe that from science’s point of view the hypothesis that consciousness (including experiential phenomena, states, and processes) exists serves no purpose. If true my premise falsifies all naturalistic ontologies according to which only concepts which are required by science refer to elements of objective reality.”

There appears to be an equivocation in Dianelos’ use of terms like “required” and “necessary.” He seems to equate these terms with “…serves no purpose.” But to say that a concept is not required or necessary certainly does not mean that it serves no purpose. Could we, in principle, produce explanations of monkey or human behavior that make no reference to consciousness? Again, of course we could. Indeed, we often do, even in everyday contexts. Why did Billy Bob drive his F-250 the wrong way up I-45? Because he had a blood alcohol level of .24. But this does not at all mean that scientific explanations that postulate conscious states are never warranted by the evidence or do not constitute the best explanations of a set of data. If such explanations do serve a purpose, then Dianelos’ assertion that they do not is simply false. Do they serve a purpose? Perhaps the more philosophical question is “Could they serve a purpose?” The answer seems to be, plainly, “yes.” There is no reason whatsoever why postulating conscious states cannot be confirmed in the same manner and to the same degree as the postulation of any other unobservable. Why not? Does Dianelos think that the possession of consciousness can have no testable consequences, or that experimental results could never justify the inference to the postulation of conscious states? Why would he think that?

Dianelos responds to my suggestion that perhaps we will someday just stop asking Chalmers’ hard question just as we long ago stopped asking questions about final causes in chemistry and physics. We didn’t stop asking questions about final causes because we discovered that there weren’t any. Rather, we just decided that such questions were pointless and unproductive and that it was a waste of time to ponder them. Dianelos objects:

“But what about other questions, such as which material systems are conscious? Such questions cannot be dropped because they are morally relevant. Correlates will not help us decide whether, say, cockroaches are conscious beings, or whether intelligent computers are conscious. Correlates will not help us decide whether our experience and personal identity can survive the destruction of our brain. Or whether it is reasonable to believe that our brain produces our consciousness in the first place (that’s the second conceptual problem I have pointed out.) So I don’t think naturalism’s problem with consciousness will ever go away.”

But why couldn’t we devise experiments that would give us the means to answer questions about cockroach or computer consciousness? Again, questions about cockroach or computer consciousness appear no different in principle than questions about any other kind of unobservable, and there is no reason to see why such questions could not be addressed with the general types of scientific inquiry we use to answer other such questions. Of course, a computer could be programmed to appear to have consciousness and so might defeat any test we could devise. Likewise, a Cartesian evil genius could defeat any empirical test we might have about anything, but this is no reason to stop empirical testing or to question its findings.

In summary then, I see no reason why there cannot be scientific explanations that legitimately invoke or postulate conscious states to explain observed phenomena. So, Dianelos’ claim that appeal to consciousness is “unnecessary” in science is either false or irrelevant. It is false if by “unnecessary” he means that appeals to or postulation of conscious states can serve no purpose in scientific investigation. They can. It is irrelevant if he means that it is possible to adduce explanations of human or animal behavior that make no mention of conscious states. This is true but it does not follow that there are no scientific contexts in which the postulation of consciousness is warranted and useful.