24
chairs and universities and legal codes are real— in the sense that they play
25
an essential role in a successful description of a certain part of the natural
26
world, within a certain domain of applicability.
27
It might seem strange that the logical possibility of a concept depends
28
on whether this or that ontology turns out to be true, but we can’t decide
29
whether “humanlike beings without consciousness” is a sensible concept
30
until we know what consciousness is.
31
In 1774, British clergyman Joseph Priestley isolated the element of oxy-
32
gen. If you asked him whether he could imagine water without any oxygen,
33
he presumably would have had no problem, since he didn’t know that water
34
is made of molecules with one oxygen atom and two hydrogens. (Water was
35S
first decomposed into hydrogen and oxygen in 1800.) But now we know
36N
better, and realize that “water without oxygen” is not conceivable. In some
358
Big Picture - UK final proofs.indd 358
20/07/2016 10:02:54
z O M b I E S A n d S t O R I E S
possible world with somewhat different laws of physics, there may be an-
01
other substance that is not H O, yet has all the phenomenological proper-
02
2
ties of water— liquid at room temperature, transparent to visible light, and
03
so on. But it wouldn’t be the water that we know and love. Likewise, if you
04
think that conscious experience is something truly distinct from the phys-
05
ical behavior of matter, you should have no trouble imagining zombies; but
06
if consciousness is just a concept we use to describe certain physical behav-
07
iors, zombies become inconceivable.
08
09
•
10
The idea that our mental experiences or qualia are not actually separate
11
things, but instead are useful parts of certain stories we tell about ordinary 12
physical things, is one that many people find hard to swallow.
13
Even with the best of intentions on both sides, a dialogue between a
14
property dualist who believes in the separate reality of mental properties
15
(call him M) and a poetic naturalist who believes they are just ways of talk-
16
ing about physical states (call her P) can be frustrating. It might go some-
17
thing like this:
18
19
M: I grant you that, when I am feeling some particular sensation,
20
it is inevitably accompanied by some particular thing happen-
21
ing in my brain— a “neural correlate of consciousness.” What
22
I deny is that one of my subjective experiences simply is such
23
an occurrence in my brain. There’s more to it than that. I also
24
have a feeling of what it is like to have that experience.
25
26
P: What I’m suggesting is that the statement “I have a feeling . . .”
27
is part of an emergent way of talking about those signals ap-
28
pearing in your brain. There is one way of talking that speaks
29
in a vocabulary of neurons and synapses and so forth, and an-
30
other way that speaks of people and their experiences. And
31
there is a map between these ways: when the neurons do a cer-
32
tain thing, the person feels a certain way. And that’s all there is.
33
34
M: Except that it’s manifestly not all there is! Because if it were, I
S35
wouldn’t have any conscious experiences at all. Atoms don’t
N36
359
Big Picture - UK final proofs.indd 359
20/07/2016 10:02:54
T H E B IG PIC T U R E
01
have experiences. You can give a functional explanation of
02
what’s going on, which will correctly account for how I actu-
03
ally behave, but such an explanation will always leave out the
04
subjective aspect.
05
06
P: Why? I’m not “leaving out” the subjective aspect, I’m suggest-
07
ing that all of this talk of our inner experiences is a useful way
08
of bundling up the collective behavior of a complex collection
09
of atoms. Individual atoms don’t have experiences, but macro-
10
scopic agglomerations of them might very well, without invok-
11
ing any additional ingredients.
12
13
M: No, they won’t. No matter how many non- feeling atoms you
14
pile together, they will never start having experiences.
15
16
P: Yes, they will.
17
18
M: No, they won’t.
19
20
P: Yes, they will.
21
22
And you can imagine how it continues from there.
23
Nevertheless, let’s make one more good- faith effort to explain to an
24
open- minded property dualist how a poetic naturalist thinks about qualia.
25
What do we mean when we say “I am experiencing the redness of red”? We
26
mean something like this:
27
28
There is a part of the universe I choose to call “me,” a collec-
29
tion of atoms interacting and evolving in certain ways. I attri-
30
bute to “myself” a number of properties, some straightforwardly
31
physical, and others inward and mental. There are certain pro-
32
cesses that can transpire within the neurons and synapses of my
33
brain, such that when they occur I say, “I am experiencing red-
34
ness.” This is a useful thing to say, since it correlates in predict-
35S
able ways with other features of the universe. For example, a
36N
person who knows I am having that experience might reliably
360
Big Picture - UK final proofs.indd 360
20/07/2016 10:02:54
z O M b I E S A n d S t O R I E S
infer the existence of red- wavelength photons entering my eyes,
01
and perhaps some object emitting or reflecting them. They
02
could also ask me further questions such as “What shade of red
03
are you seeing?” and expect a certain spectrum of sensible an-
04
swers. There may also be correlations with other inner mental
05
states, such as “seeing red always makes me feel melancholy.”
06
Because of the coherence and reliability of these correlations, I
07
judge the concept of “seeing red” to be one that plays a useful
08
role in my way of talking about the universe as described on hu-
09
man scales. Therefore the “experience of redness” is a real thing.
10
11
It’s a mouthful, and nobody would ever mistake it for a Shakespearean
12
sonnet. But there’s a kind of poetry there, if you look closely enough.
13
14
•
15
There are two points of view relevant to consciousness that are close cousins
16
of poetic naturalism, but different in important ways.
17
One view is to argue that all of these so-called qualia or inner experi-
18
ences simply don’t exist— they are illusions. Maybe you thought you had
19
inner experiences, but that is an antiquated part of our intuitive view of the
20
world, a relic of a prescientific age. Now we know better, and should use a
21
more updated and appropriate set of concepts.
22
The other perspective is a strong form of reductionism that insists that
23
subjective experiences simply are physical processes happening in the brain.
24
They exist, but they can be identified with specific neural correlates. A fa-
25
mous example along these lines comes from philosopher Hilary Putnam,
26
who contemplated— to refute the idea, not to defend it— the position that
27
“pain” is to be literally identified with “the firing of C-fibers.” (C-fibers are
28
a part of the nervous system that carries pain signals.)
29
A poetic naturalist has no trouble saying that conscious experiences ex-
30
ist. They are not part of the fundamental architecture of reality, but they
31
serve as essential pieces of an emergent effective theory. The best way we
32
have of talking about people and their behaviors makes important reference
33
to their inner mental states; therefore, by the standards of poetic natural-
34
ism, those states are real, existing things.
S35
There is a relationship between the different ways we have of talking
N36
361
Big Picture - UK final proofs.indd 361
20/07/2016 10:02:54
T H E B IG PIC T U R E
01
about the world, including the human- level vocabulary that includes our
02
subjective experiences, and the cell- biological level that includes firing nerve
03
fibers, and the particle- physics level that includes fermions and bosons. The
04
relationship is that certain states in the more comprehensive theories (par-
05
ticles, cells) correspond to unique states in the coarse- grained theories
06
(people, experiences). The reverse relationship is typically not unique; there
07
may be a large number of arrangements of atoms that correspond to “me
08
being in pain.”
09
A subtle but important distinction lurks between “there is a map be-
10
tween the concepts of different theories” and “the concepts of the coarse-
11
grained theories are to be identified with certain states in the more
12
comprehensive theories,” such as “pain is to be identified with the firing of
13
C-fibers.” The difference is important because granting the latter, stronger
14
formulation gets us in trouble. Putnam, for example, would then want to
15
ask, “Do you mean to say there can be no such thing as pain without the
16
existence of C-fibers? That artificial beings, or aliens, or even very different
17
animals here on Earth, are by definition incapable of feeling pain?”
18
We don’t want to say that, and we don’t have to. There are certain con-
19
figurations of atoms that correspond to “a human being feeling pain,” but
20
there could be other configurations of atoms that correspond to “a Wookiee
21
feeling pain,” or any related instantiation of the concept. (There is nothing
22
in principle that prevents a computer from feeling pain.) Poetic naturalism
23
is “poetic” because there are different stories we can tell about the world,
24
many of them capturing some aspects of reality, and all useful in their ap-
25
propriate context.
26
There’s no reason for us to pretend that subjective experiences don’t ex-
27
ist, or on the other hand that they “are” something happening in the brain.
28
They are essential concepts within a way of talking about things happening
29
in our brains, and that makes all the difference.
30
31
32
33
34
35S
36N
362
Big Picture - UK final proofs.indd 362
20/07/2016 10:02:54
01
02
42
03
04
Are Photons Conscious?
05
06
07
08
09
10
11
12
I
13
f consciousness were something over and above the physical properties
14
of matter, there would be a puzzle: what was it doing for all those bil-
15
lions of years before life came along?
16
Poetic naturalists have no problem with this question. The appearance
17
of consciousness is a phase transition, like water boiling. The fact that suf-
18
ficiently hot water is in the form of a gas doesn’t mean that there was always
19
something gaslike about the water, even when it was in the form of liquid;
20
the system simply acquired new properties as its situation changed.
21
But if you believe that mental properties are an additional ingredient,
22
over and above the underlying physical substrate, then the question of what
23
they were doing for most of the history of the universe is a pointed one. The
24
most straightforward answer is that those mental properties were always
25
there, even before there were brains or even organisms. Even the individual
26
atoms and particles that were bumping into one another in the early uni-
27
verse, or are currently doing so at the center of the sun or in the desolate
28
cold of intergalactic space, are equipped with mental properties of their
29
own. They would be, in this sense, a little bit conscious.
30
The suggestion that consciousness pervades the universe, and is a part of
31
every piece of matter, goes by the name of panpsychism. It’s an old idea, go-
32
ing back arguably as far as Thales and Plato in ancient Greece, as well as in
33
certain Buddhist traditions. In its modern guise it has been contemplated
34
seriously by philosophers like David Chalmers and neuroscientists such as
S35
N36
363
Big Picture - UK final proofs.indd 363
20/07/2016 10:02:54
T H E B IG PIC T U R E
01
Giulio Tononi and Christof Koch. Here is Chalmers, admirably biting the
02
bullet and accepting the consequences of what such a view would imply:
03
04
Even a photon has some degree of consciousness. The idea is
05
not that photons are intelligent or thinking. It’s not that a pho-
06
ton is wracked with angst because it’s thinking, “Aww, I’m al-
07
ways buzzing around near the speed of light. I never get to slow
08
down and smell the roses.” No, not like that. But the thought is
09
maybe photons might have some element of raw, subjective feel-
10
ing, some primitive precursor to consciousness.
11
12
Consciousness, or at least protoconsciousness, could be analogous to
13
“spin” or “electric charge”— one of the basic properties characterizing each
14
bit of matter in the universe.
15
•
16
17
It’s worth taking the implications of this idea seriously, and seeing how well
18
it fits in with what we know about the physics of photons.
19
Unlike brains, which are complicated and hard to explain, elementary
20
particles such as photons are extraordinarily simple, and therefore relatively
21
easy to study and understand. Physicists talk about different kinds of par-
22
ticles having different “degrees of freedom”— essentially, the number of dif-
23
ferent kinds of such particles that there are. An electron, for example, has
24
two degrees of freedom. It has both electric charge and spin, but the electric
25
charge can take on only one value (–1), while the spin comes in two possi-
26
bilities: clockwise or counterclockwise. One times two is two, for two total
27
degrees of freedom. An up quark, by contrast, has six degrees of freedom;
28
like an electron, it has a fixed charge and two possible ways of spinning, but
29
The Big Picture Page 61