Category: Nagel, Thomas

Can Reason Be Understood Naturalistically? More Notes on Nagel

This is the third in a series of posts on Thomas Nagel's Mind and Cosmos (Oxford 2012).  The first is an overview, and the second addresses Nagel's reason for rejecting theism.  This post will comment on some of the content in Chapter 4, "Cognition."

In Chapter 4,  Nagel tackles the topic of reason, both theoretical and practical.  The emphasis is on theoretical reason, with practical reason receiving a closer treatment in the following chapter entitled "Value."

We have already seen that consciousness presents a problem for evolutionary reductionism due to its irreducibly subjective character.  (For some explanation of this irreducibly subjective character, see my Like, What Does It Mean?)

'Consciousness' taken narrowly refers to phenomenal consciousness, pleasures, pains, emotions, and the like, but taken widely it embraces also thought, reasoning and evaluation.  Sensory qualia are  present in nonhuman animals, but only we think, reason, and evaluate.  We evaluate our thoughts as either true or false, our reasonings as either valid or invalid, and our actions as either right or wrong, good or bad.  These higher-level capacities can be possessed only by beings that are also conscious in the narrow sense.  Thus no computer literally thinks or reasons or evaluates the quality of its reasoning imposing norms on itself as to how it ought to reason if it is to arrive at truth; at best computers simulate these activities.  Talk of computers thinking is metaphorical.  This is a contested point, of course.  But if mind is a biological phenomenon as Nagel  maintains, then this is not particularly surprising.

What makes consciousness fascinating is that while it is irreducibly subjective, it is also, in its higher manifestations, transcensive of subjectivity. (This is my formulation, not Nagel's.)  Mind is not trapped within its interiority but transcends it toward impersonal objectivity, the "view from nowhere."  Consciousness develops into "an instrument of transcendence that can grasp objective reality and objective value." (85)  Both sides of mind, the subjective and the objective, pose a problem for reductive naturalism.  "It is not merely the subjectivity of thought but its capacity to transcend subjectivity and to dsiscover what is objectively the case that presents a problem." (72)

Exactly right!  One cannot prise apart the two sides of mind, segregating the qualia problem from the intentionality problem, calling the former 'hard' and imagining the latter to be solved by some functionalist analysis.  It just won't work.  The so-called Hard Problem is actually insoluble on reductive naturalism, and so is the intentionality problem.  (Some who appreciate this go eliminativist — which is a bit like getting rid of a headache by blowing one's brains out.)

The main problem Nagel deals with in this chapter concerns the reliability of reason.  Now it is a given that reason is reliable, though not infallible, and that it is a source of objective knowledge.  The problem is not whether reason is reliable as a source of knowledge, but how it it is possible for reason to be reliable if  evolutionary naturalism is true.  I think it is helpful to divide this question into two:

Q1. How can reason be reliable if materialist evolutionary naturalism is true?

Q2. How can reason be reliable if evolutionary naturalism is true?

Let us not forget that Nagel himself is an evolutionary naturalist.  He is clearly  a naturalist as I explained in my first post, and  he does not deny the central tenets of the theory of evolution.  His objections are to reductive materialism (psychophysical reductionism) and not to either naturalism or evolution. Now Nagel is quite convinced, and I am too, that the answer to (Q1) is that it is not possible for reason to be relied upon in the manner in which we do in fact rely upon it, if materialism is true.  The open question for Nagel is (Q2).  Reason is reliable, and some version of evolutionary naturalism is also true.  The problem is to understand how it is possible for both of them to be true.

Now in this post I am not concerned with Nagel's tentative and admttedly speculative  answer to (Q2).  I hope to take that up in a subsequent post.  My task at present is to understand why Nagel thinks that it is not possible for reason to be reliable if materialism is true.

Suppose we contrast seeing a tree with grasping a truth by reason. 

Vision is for the most part reliable:  I am, for the most part, justified in believing the evidence of my senses.  And this despite the fact that from time to time I fall victim to perceptual illusions.  My justification is in no way undermined if I think of myself and my visual system as a product of Darwinian natural selection.  "I am nevertheless justified in believing the evidence of my senses for the most part, because this is consistent with the hypothesis that an accurate representation of the world around me results from senses shaped by evolution to serve that function." (80)

Now suppose I grasp a truth by reason. (E.g., that I must be driving North because the rising sun is on my right.)  Can the correctness of this logical inference be confirmed by  the reflection that the reliability of logical thinking is consistent with the hypothesis that evolution has selected instances of such thinking for accuracy?

No, says Nagel and for a very powerful reason.  When I reason I engage in such operations as the following: I make judgments about consistency and inconsistency; draw conclusions from premises; subsume particulars under universals, etc.  So if I judge that the reliability of reason is consistent with an evolutionary explanation of its origin, I presuppose the reliability of reason in making this very judgement.  Nagel writes:

It is not possible to think, "reliance on my reason, including my reliance on this very judgment, is reasonable because it is consistent with its having an evolutionary explanation." Therefore any evolutionary account  of the place of reason presupposes reason's validity and cannot confirm it without circularity. (80-81)

Nagel's point is that the validity of reason can neither be confirmed nor undermined by any evolutionary account of its origins.  Moreover, if reason has a merely materialist origin it would not be reliable, for then its appearance would be a fluke or accident.  And yet reason is tied to organisms just as consciousness is.  Nagel faces the problem of explaining how reason can be what it is, an "instrument of transcendence" (85) and a "final court of appeal" (83), while also being wholly natural and a product of evolution.  I'll address this topic in a later post. 

Why can't reason be a cosmic accident, a fluke?  This is discussed in my second post linked to above, though I suspect I will be coming back to it.

Nagel’s Reason for Rejecting Theism

This is the second in a series.  My overview of Thomas Nagel's new book, Mind and Cosmos, is here.

I agree with Nagel that mind is not a cosmic accident.  Mind in all of its ramifications (sentience, intentionality, self-awareness, cognition, rationality, normativity in general) could not have arisen from mindless matter.  To put it very roughly, and in my own way, mind had to be there already and all along in one way or another.  Not an "add-on" as Nagel writes, but "a basic aspect of nature." (16) 

Two ways mind could have been there already and all along are Nagel's panpsychistic way and the theistic way.  My task in this entry is to understand and then evaluate Nagel's reasons for rejecting theism.  

But first let's back up a step and consider the connection between mind and intelligibility.  That the world is intelligible is a presupposition of all inquiry.  The quest for understanding rests on the assumption that the world is understandable, and indeed by us.  The most successful form of this quest is natural science.  The success of the scientific quest is evidence that the presupposition holds and is not merely a presupposition we make.  The scientific enterprise reveals to us an underlying intelligible order of things not open to perception alone, although of course the confirmation of scientific theories requires perception and the various instruments that extend it.

Now what explains this underlying rational order? Two possibilities.  One is that nothing does: it's a brute fact.  It just happens to be the case that the world is understandable by us, but it might not have been.  The rational order of things underpins every explanation but  itself has no explanation.  The other possibility is that the rational order has an explanation, in which case it has an explanation by something distinct from it, or else is self-explanatory.  On theism, the world's  rational order is grounded in the divine intellect and is therefore explained by God.  On what I take to be Nagel's view, the rational order is self-explanatory, a necessary feature of anything that could count as a cosmos.

Nagel views the intelligibility of the world as "itself part of the deepest explanation why things are as they are." (17).  Now part of the way things are is that they are understandable by us.  Given that the way things are is intelligible, it follows that the intelligibility of the world is self-explanatory or self-grounding.

"The intelligibility of the world is no accident." (17)  The same is true of mind.  The two go together: an intelligible world is one that is intelligible to mind, and mind is mind only if it can 'glom onto' an antecedent order of things.  (This is my way of putting it, not Nagel's!)  Intelligibility is necessarily mind-involving, and mind (apart from mere qualia) is necessarily an understanding of something.  One could say that there is an antecedent community of nature between mind and world which allows mind to have an object to understand and the world to be understandable by mind.  What I am calling the antecedent community of nature between mind and world Nagel expresses by saying that "nature is such as to give rise to conscious beings with minds; and it is such as to be comprehensible to such beings." (17)

That neither mind nor intelligibility are cosmic accidents, and that they 'go together' as just explained  could be accepted by both Nagelian panpsychists and theists.  So why does Nagel reject theism?

His main reason seems to be couched in the following quotations:

. . . the disadvantage of theism as an answer to the desire for comprehensive understanding is not that it offers no explanations but that it does not do so in the form of a comprehensive account of the natural order. [. . .] But it would not be the kind of understanding that explains how beings like us fit into the world.  The kind of intelligibility that would still be missing is intelligibility of the natural order itself — intelligibility from within. (25-26)

Nagel does not do a very good job of presenting his argument clearly, but the following is what I take him to be driving at.

Materialism cannot explain the origin of life from inanimate matter, the origin of consciousness from pre-conscious life, or the origin of reason in conscious beings.  Nondeistic theism can explain these crucial transitions by means of divine interventions into the workings of nature.  (Deism would leave the crucial transitions as brute facts and is  rejectable for this reason.)  To subscribe to such interventionist hypotheses, however, is to deny that there is a comprehensive natural order.  Nature would not be intelligible from within itself, in its own terms.  So maybe Nagel's argument could be put like this:

1. Nature is immanently intelligible: it has the source of its intelligibility entirely within itself and not from a source outside itself.

2. On theism, nature is not immanently intelligible: God is the source of nature's intelligibility. (This is because divine intervention is needed to explain the crucial transitions to life, to consciousness, and to reason, transitions which otherwise would be unintelligible.)

Therefore

3. Theism suffers from a serious defect that make it reasonable to pursue a third course, panpsychism, as a way to avoid both materialism and theism.

Now I've put the matter more clearly than Nagel does, but I'd be surprised if this is not what he is arguing, at least on pp 25-26.

As for evaluation, the argument as presented is reasonable but surely not compelling. A theist needn't be worried by it.  He could argue that it begs the question at the first premise. How divine interventions into the course of nature are so much as possible is of course a problem for theists, but Plantinga has an answer for that.  The theist can also go on the attack and mount a critique of panpsychism, a fit topic for future posts. 

There is also the question of why the cosmos exists at all.  It is plausible to maintain that the cosmos is necessarily intelligible, that it wouldn't be a cosmos if it weren't.  But necessary intelligibility is consistent with contingent existence.  Will Nagel say that the cosmos necessarily exists?  How would he ground that?  Panpsychism, if tenable, will relieve us of the dualisms of matter-life, life-consciousness, mind-body.  But it doesn't have the resources to explain the very existence of the cosmos.

Thomas Nagel, Mind and Cosmos: Overview

I think I shall have to write a number of posts on this exciting and idea-rich book by one of our best philosophers.  Here is the first.

Short (128 pp.) and programmatic, Thomas Nagel's new book explores the prospects of an approach in the philosophy of mind that is naturalistic yet not materialistic.  His approach is naturalistic in that he locates the source of the world's intelligibility in it, and not in a transcendent being such as God outside it.  As Nagel rightly observes, "Theism pushes the quest for intelligibility outside the world." (p. 45)

Nagel's  approach is also naturalistic in that he views mind as a biological phenomenon as it could not be if substance dualism were true.  But while naturalistic, Nagel also rejects "psychophysical reductionism" or "reductive materialism."  Thus he rejects naturalism as currently articulated without embracing any form of anti-naturalism such as theism.  Nagel, we might say, seeks a middle path between theistic anti-naturalism and materialistic naturalism. The latter is just materialism which Nagel defines as follows:

Materialism is the view that only the physical world is irreducibly real, and that a place must be found in it for mind, if there is such a thing.  This would continue the onward march of physical science, through molecular biology, to full closure by swallowing up the mind in the objective physical reality from which it was initially excluded. (37)

This is a useful definition.  Materialism is either eliminativist or reductivist.  Now obviously there is such a thing as mind, so eliminativism is not an option. (41)  My arguments against it here.  So the materialist must try to show that mind  belongs to objective physical reality and that everything about it is understandable in the way everything else in objective physical reality is understandable.  In this way materialism closes upon itself, explaining not only the world the mind engages, but the engaging mind itself.  I agree with Nagel that reductive materialism is untenable.

Treading his via media between theism and materialism,  Nagel reopens the case for neutral monism and panpsychism. How does he get to these positions?  This is what I will try to figure out in this post.

Mind is a biological phenomenon.  We are organisms in nature, not Cartesian egos contingently attached to physical bodies.    But we are conscious organisms.   We are subjects of such qualitative states as pleasure and pain, and we are  individuals with a subjective point of view.  If psychophysical reductionism fails, as both Nagel and I maintain, then physical science, even if it can explain our existence as organisms adapted to an environment,  cannot explain our existence as conscious organisms.  We are not just objects in the world, we are subjects for whom there is a world.  Even if the first fact can be adequately explained by physical science, the second, our subjectivity,  cannot be.

Given the failure of psychophysical reductionism, and given that mind is a biological phenomenon encountered only in conscious organisms that have evolved from pre-conscious organisms, evolutionary theory cannot be a purely physical theory. (44)  The 'makings' of conscious organsims must already be present in pre-conscious life forms.  In this way the mind-body problem spreads to the entire cosmos and its history.  Thus "the mind-body problem is not just a local problem" that concerns such minded organisms as ourselves. (3) 

Inanimate matter evolved into pre-conscious life forms, and these evolved into conscious life forms.  Since conscious organisms qua conscious cannot be understood materalistically, the same is true of pre-conscious life forms: the reduction of biology to physics and chemistry will also fail.   This is because life must contain within it the 'makings' of consciousness.  That is my way of putting it, not Nagel's. 

Turning it around the other way, if we are to have an adequate naturalistic explanation of conscious organisms, then this cannot be "a purely physical explanation." (44)  And so Nagel floats the suggestion of a global (as opposed to local) neutral monism "according to which the constituents of the universe have properties that explain not only its [mental life's] physical but its mental character." (56)  Conscious organisms are composed of the same ultimate stuff as everything else is.  For this reason, neutral monism cannot be kept local but goes global or "universal." (57)  The idea, I take it, is that even the merely physical is proto-mental, the merely living being even more so.  When conscious organisms arrive on the scene, the proto-mental constituents achieve an arrangement and composition that amounts to mental life as we know it.

Now how do we get from this universal neutral monism to panpsychism?  Well, a universal neutral monism just is panpsychism: the ultimate constituents of nature are all of them proto-mental.  Mind is everywhere since everything is composed of the same proto-mental constituents.  But it is equally true that matter is everywhere since there is nothing mental or proto-mental that is not also physical.

Thus we arrive at a position that is neither theistic nor reductively materialistic.

Let me now try to list the key premises/assumptions in Nagel's argument for his panpsychistic naturalism.

1. Consciousness is real.  Eliminativist materialism is a complete non-starter.

2. Naturalism:  Consciousness occurs only in conscious organisms, hence cannot occur without physical realization.  Mind is a biological phenomenon.  No God, no Cartesian minds.  No substance dualism, no theism.

3. Reductive Materialism  (psychophysical reductionism) is untenable.

4. Consciousness cannot be a brute fact.  Mind is not an accident but "a basic aspect of nature." (16) It cannot be that consciousness just inexplicably occurred at a certain point in evolutionary history when organisms of a certain physical complexity appeared.  The arrival of conscious organisms needs an explanation, and this explanation cannot be an explanation merely of their physical character.  It must also explain their mental character.  But this materialism cannot do.  Hence "materialism is incomplete even as a theory of the physical world, since the physical world includes conscious organisms as its most striking occupants." (45)

5.  Nature is intelligible.  Its intelligibility is inherent in it and thus not imposed on it by us or by God.  The intelligibility of nature is not a brute fact: nature doesn't just happen, inexplicably, to possess a rational order that is understandable by us. I take Nagel's position to be that intelligibility is a necessary feature of anything that could count as a cosmos.  Thus it needs no explanation and surely cannot have a materialist one: it cannot possibly be the case that the intelligibility of nature arose at some time in the past via the operation of material causes.   The universe is so constituted as to be understandable, and we, as parts of it, are so constituted as to be able to understand it.  (16-17)

I accept all of these propositions except (2).  So in a subsequent post I must examine whether Nagel's case against theism is stronger than his case for his panpsychism.