Consciousness is (Probably) a Biological Phenomenon
Richard Brown
Much energy in the philosophy of mind has been devoted to the question of whether
consciousness is, or even could be, physical. However there is an equally important,
yet orthogonal, question that has not been as widely discussed. This is the question
of whether consciousness is fundamentally a biological phenomenon or whether it
is an ‘organizational invariant,’ (Chalmers 1995; Chalmers 1996), or is ‘substrate
independent’ (Bostrom 2003). On one side of the debate are those who affirm that
this is so and thus hold that a properly organized computer program could in fact be
conscious in just the way that you or I ordinarily are. Because of this I will call this
view computationalism about consciousness. On the other side of the debate are
those that hold that consciousness is a distinctively biological phenomenon and that
a maximally specific computer simulation of those biological processes would not
result in consciousness. I will call this kind of view biologism about consciousness.
The debate over computationalism is independent of the between the physicalist
and non-physicalist. A non-physicalist may hold that a suitably programmed
computer would come to instantiate non-physical qualia (as David Chalmers (1996)
has suggested). All that would be required is that there be fundamental laws of
nature that relate the computational states to non-physical qualia. While a
physicalist may hold that the implemented program itself is conscious. Physicalists
who endorse computationalism usually do so by endorsing some kind of
(computational) functionalism whereas physicalists who endorse biologism usually
do so by endorsing some kind of type identity theory.
Though there are those that defend the biological view (Searle 2004, Block 2009)
the dominant view is computationalism. This is perhaps in part due to the
popularity of functionalist views. However it is very rarely argued for. It is much
more common to hear remarks to the effect that ‘neurons aren’t magic’. That is not
an argument. It is also not enough to cite arguments for functionalism either. For
instance the argument from multiple realizability at most suggests that there may be
other biological configurations that may be conscious. It is quite another thing to
suggest that non-biological systems could be conscious.
Of course one might invoke the conceivability of non-biological creatures that are
conscious. But doing so begs the question. It may be the case that when we imagine
that there is a silicon system that is conscious, a commander Data type robot, we
imagine something that is the equivalent of xyz. Given that we know that water is
essentially H2O we know that the xyz is not a candidate to be our world. Our world
could not have been the xyz world. If biologism is true then the same is true for the
commander Data world. It is conceivable but it is not a way our world could have
been. Given this what we need is an independent argument for computationalism.
Perhaps the best (only?) argument for computationalism is David Chalmers’
Dancing Qualia and Fading Qualia arguments. Recently Chalmers (2010) has come
to change his mind on the strength of the dancing qualia argument. His change of
heart was motivated by empirical findings from cognitive neuroscience, and in
particular change blindness. In this paper I will argue that we have further empirical
findings that motivate a questioning of the strength of the fading qualia argument.
What this shows is that one can reasonably think that biologism is true. And absent
any reasons to think that it isn’t true it should probably be the default view. Before
introducing the empirical results I first turn to looking at the original arguments and
the reasons that Chalmers has given for his change of heart on their relative
strength. In section three I introduce the empirical results from the partial report
experiments. The upshot is that the original dancing and fading qualia arguments
look less plausible and so biologism about consciousness is more than likely true
after all.
II. Flip-Flopping on Dancing and Fading Qualia
These arguments both have roughly the same form. We start with a fully biological
creature that is fully conscious. For vividness we can imagine that they are having
an intense headache, a migraine say, while watching a movie and eating a box of
sour patch kids. We then replace one of their neurons with a functionally identical
computer chip. We can even imagine that we are able to do so in such a way that the
subject is unaware that it is happening (the wonders of nanotechnology being what
there are and all). We then imagine a series of replacements like this, with the
second in the line having two neurons replaced, the third 3 neurons, etc. until we
reach the other end where we have completely replaced the brain with computer
chips. At each stage in the series the subject we end up with is functionally identical
to me, or you. Given this there will be no way that the subject’s behavior can change
in any way. As the neurons are being replaced the subject continues to complain of
the headache, asking for the volume to be tuned down and remarking that the taste
of the sour patch kids helps to distract from the migraine, etc. If we assume that
computationalism is false then in the fading qualia case we would have to imagine
that as we replace the neurons with silicon our conscious experience fades as a light
on a dimmer switch would even though our behavior continues to be the same
through out. In the dancing qualia case we imagine that we have a switch that
activates and deactivates the group of silicon chips that has replaced the neural
circuitry that is responsible for a certain conscious experience. As we flip the switch
our conscious experience is blinking in and out of existence yet, again, your behavior
continues to be the same through out.
So, if we assume that computationalism is false, then in each case we end up with
subjects that are radically out of touch with their own conscious experiences. They
say that they have an intense headache but that isn’t true. In one case the headache
is dim and in the other it is blinking in and out of existence. In our world we
typically do not find ourselves in this kind of position. It seems plausible that we are
not radically out of touch with our own conscious experience. So it is much more
plausible to think that, while these scenarios are possible in some sense, they do not
describe the actual world with its actual laws. In other words, it is safe to assume
that in our actual world the complete silicon brain would be conscious in just the
way that the biological creature originally was.
These arguments are not presented as strict reductios but are rather offered to
show how strange biologism is and the consequences of the view. If biologism is
true then we can have systems that are radically out of touch with their own
conscious experience and, for all we know, it could be happening right now! Since
this seems prima facie implausible we have a prima facie case against biologism and
for computationalism.
Originally Chalmers argued that the dancing qualia argument was stronger than the
fading qualia argument. But in what sense is the one argument supposed to be
stronger than the other? In his original paper on this (Chalmers 1995) he seems to
suggest that the absent qualia argument is stronger because it has a stronger
conclusion. The fading qualia argument, if successful, establishes only that the
property of being conscious is an organizational invariant. So if it works it shows
that there will be something that it is like for my silicon isomorph, but it does not
show that our conscious experiences will be the same. For all the fading qualia
argument shows when I and my silicon isomorph are in the same computational
state I may be consciously experiencing red while the isomorph experiences blue, or
even some color that is completely alien to me. The dancing qualia argument, on the
other hand, is supposed to suggest the stronger conclusion that the silicon isomorph
is not only conscious but that their experience is exactly the same as my conscious
experience (given that we are in computationally identical states).
In his 1996 book The Conscious Mind he indicates another sense of strength. In this
second sense the dancing qualia argument is thought to lead to an intuitively more
bizarre outcome and so is much harder to accept. The subject is having a very vivid
conscious experience blink in and out of existence; how could they fail to notice
that? He suggests that one might be able to bite the bullet on fading qualia but
dancing qualia are just too strange to be real (Chalmers 1996 p 270).
Chalmers has since come to reverse this decision based on considerations of change
blindness. Here is what he says in a footnote in his recent book The Character of
Consciousness (Chalmers 2010), which I reproduce in its entirety,
I still find this [dancing qualia] hypothesis very odd, but I am now inclined to
think it is something less than a reductio. Work on change blindness has
gotten us used to the idea that large changes in consciousness can go
unnoticed. Admittedly, those changes are made outside of attention, and
unnoticed changes in the contents of attention would be much stranger, but
it is perhaps not so strange as to be ruled out in all circumstances. Russellian
monism…also provides a natural model in which such changes could occur.
In The Conscious Mind I suggested that this “dancing qualia” argument was
somewhat stronger than the “fading qualia” argument given there; I would
now reverse that judgment (page 24 note 7)
In what sense, then, are we to take the reversal of strength that Chalmers indicates
in the above footnote? It seems implausible that it should be the first notion. It can’t
be the case that now the fading qualia argument establishes that computational
isomorphs have the same kind of conscious experience as I do. So it must be the case
that Chalmers now finds the fading qualia scenario to be more intuitively bizarre
than the dancing qualia scenario.
This, in turn, suggests that it is not such a high cost for those attracted to biologism
to bite this bullet. If this is right then Chalmers will have to back off of the claim that
the computational isomorph’s experience is just like mine but he can fall back on the
fading qualia argument and insist that the cost is too high to bite the bullet on that
argument. If so then consciousness itself –that is, the property of their being
something that it is like for the system— may still be an organizational invariant
and so a more modest form of computationalism may still be true.
It is striking that empirical results have such a dramatic effect on our intuitions
about strangeness. What can seem intuitively bizarre from the armchair can turn
out to empirically be verified. One might think that the mere fact that change
blindness shows us how wrong we can be in our intuitive assessment of these kinds
of thought experiments would give us pause in endorsing the strength of the fading
qualia case. I think that this all by itself is a prima facie reason to doubt the fading
qualia argument but even if one resists this somewhat empirically jaded suspicion
there are further empirical results that should cause us to re-assess the fading
qualia argument as well.
III. Partial Report and Fading Qualia
In this section I will present a brief sketch of the partial report paradigm and the
inattentional inflation results. The interpretation of the results is something that is
currently hotly debated in the literature (Kourider 2010, Block 2012, Lau &
Rosenthal 2012, Brown 2012, Lau & Brown forthcoming). The argument I will
present does not rely on any one specific interpretation turning out to be correct. As
I will show, the argument relies on only the most general interpretation of the
experimental results. In fact the interpretation is so general that all of the relevant
parties agree on this.
In these experiments subjects are presented with an array of letters or objects that
arranged in some particular fashion (e.g. in a city-block grid, or in clock face circular
arrangement). After a brief presentation subjects are asked to freely report as to the
identity of the objects they saw. Subjects, overall, cannot report the identities of all
of the objects or letters. However, if a subject is cued, by a tone say, to recall a
specific row or item they do very well. The debate has centered on whether subjects
consciously experience all of the letters or objects or if they instead represent them
in some sparse or generic way. Once side of the debate holds that consciousness is
rich and that there is more in our conscious experience than we able to report, while
the other side holds that consciousness is sparse and that we experience less than
we think we do (at least consciously). This debate, while interesting, does not
concern us here.
All parties to this debate agree that there are these generic representations
involved. Experimental results have shown that subjects can correctly report only 34 out of 12 objects. Further calculations suggest that at least 10.4 of the letters must
be represented in sufficient detail so as to allow identification. This suggests that
subjects may have some partial or degraded conscious representations, as that
would explain why they are not able to name those letters. Of course it may also be
the case that they do consciously experience them but just forget their identities. To
test this experimenters have replaced some of the letters in the display with things
that are not letters (an upside down ‘r’ or an ‘@’ sign) and subjects failed to report
anything abnormal, and when asked, said that there were only letters present.
So while all parties agree that some of the objects are represented in a partial or
indeterminate way, the question has been whether only the 3-4 the subjects get
right are represented in full detail (consciously but not accessed) with all of the
others being partial or degraded representations or whether instead it is only a few
of the representations that are degraded with the majority being represented in full
detail. Even those who believe that phenomenal consciousness overflows access are
committed to there being at least some degraded or partial representations in these
situations. But these subjects believe that they see all of the letters or objects.
Thus we seem to have ended up showing that normal subjects can in fact have
partially degraded experiences and yet be unaware of it. This provides us with
motivation to question the fading qualia argument. Now, it is true that in that kind of
case we are considering something which is much, much more radical than what is
happening in the partial report cases. In that case the subject has some partially
degraded experience and thinks it is non-degraded. In the fading qualia case the
subject thinks it is having an intense headache even though the actual intensity of
the headache consists in just a few bits. But what these kinds of considerations
suggest is that it is not such a drastic scenario after al.
Chalmers does consider one kind of empirical evidence in his original article. He
considers the case of someone who denies that they are blind. In that kind of case,
he argues, it is plausible that the subject is rationally defective. The have no visual
information and yet they believe that they do. Because of this non-standard way that
their experience and their beliefs are connected this doesn’t give us any reason to
change our minds. However in the case that we have been considering here we do
not have this problem. Subjects are not suffering from any kind of irrationality in
these paradigms. They are simply asked to look at a bunch of objects that are briefly
presented on the screen and then to report on what they had seen. It is true that the
objects in question are presented relatively briefly and subjects do not get to look at
the stimuli for an extended time, as we would in ordinary life.
To be sure, this is not as radical as the kind of case imagined in the fading qualia
scenario, where one’s conscious experience is severely degraded, but it does suggest
that it is not as strange as one might have thought. It is basically a very severe case
of what is going on in our everyday conscious lives, exactly parallel to the change
blindness case for dancing qualia. The partial report paradigm is just one of several
new empirical findings that seem to vindicate fading qualia. For reasons of space I
cannot go into other finding from so-called ‘inattentional inflation’ where subjects
overestimate the visibility of stimuli outside of where they are attending.
IV. Conclusion
The fading and dancing qualia thought experiments were never offered as strict
reductios of biologism but were instead aimed at showing that biologism was
unlikely to be true because it entailed some unlikely or implausible consequences
about the relationship between our conscious experience and our knowledge of that
conscious experience. However, as we have seen, we have good empirical reason to
think that these results are a good deal less implausible than they appear to be from
the armchair. Of course this doesn’t show that biologism is true. Rather, it shows
that there is not much cost in biting the bullet in both cases and so one can
reasonably hold that biologism is true and admit that there might be cases of
dancing and fading qualia. Science has shown us that the world is far stranger than
any of us could have ever imagined.