1. Defining the problem: The inverted spectrum
Philosophy
has been called a preoccupation with the questions entertained by adolescents,
and one adolescent favorite concerns our knowledge of other persons’ “private
experience” (raw experience or qualia). A philosophers’ version is the
“inverted spectrum”: how do I know you see “red” rather than “blue” when you see this
red print? How could we tell when we each link the same terms to the
same outward descriptions? We each will say “red” when we see the print, even
if you really see “blue.”
The
intuition that allows us to be different this way is the intuition of raw experience (or of qualia). Philosophers of mind have
devoted considerable attention to reconciling the intuition that raw experience
exists with the intuition that inverted-spectrum indeterminacy has unacceptable
dualist implications making the mental realm publicly unobservable, but it’s time for nihilism
about qualia, whose claim to exist rests solely on the
strength of a prejudice.
A. Attempted solutions to the inverted spectrum.
One account
would have us examine which parts of the brain are activated by each
perception, but then we rely on an unverifiable correlation between brain
structures and “private experience.” With only a single example of private
experience—our own—we have no basis for knowing what makes private experience
the same or different between persons.
A subtler
response to the inverted spectrum is that red and blue as experiences are
distinct because red looks “red” due to its being constituted by certain
responses, such as affect. Red makes you alert and tense; blue, tranquil or
maybe sad. What we call the experience of red, on this account, just is the
sense of alertness, and other manifestations. The hope is that identical observable
responses to appropriate wavelengths might explain qualitative redness. Then, we
could discover we experience blue when others experience red by finding that we
idiosyncratically become tranquil instead of alert when exposed to the long
wavelengths constituting physical red. This complication doesn’t remove the radical
uncertainty about experiential descriptions. Emotion only seems more capable than cognition of explaining raw experience because emotional events are memorable. The affect theory doesn't answer how an
emotional reaction can constitute a raw
subjective experience.
B. The “substitution bias” of solving the “easy problem of consciousness” instead of the “hard problem.”
As in those
examples, attempts at analyzing raw experience commonly appeal to the substitution process that psychologist Daniel Kahneman discovered in many cognitive fallacies. Substitution is the unthoughtful replacement of an easy for a related
hard question. In the philosophy of mind, the distinct questions are actually termed
the “easy problem of consciousness” and the “hard problem of consciousness,”
and errors regarding consciousness typically are due to substituting the “easy
problem” for the “hard,” where the easy problem is to explain some function
that typically accompanies
“awareness.” The philosopher might substitute knowledge of one’s own brain
processes for raw experience; or, as in the previous example, experience’s
neural accompaniments or its affective accompaniments. Avoiding the “substitution bias” is particularly
hard when dealing with raw awareness, an unarticulated
intuition; articulating it is a present purpose.
2. The false intuition of direct awareness
A. Our sense that the existence of raw experience is self-evident doesn’t show that it is true.
The theory that
direct awareness reveals raw experience has long been almost sacrosanct in
philosophy. According to the British Empiricists, direct experience consists of
sense data and forms the indubitable basis of all synthetic knowledge. For
Continental Rationalist Descartes, too, my direct experience—“I think”—indubitably
proves my existence.
We do have
a strong intuition that we have raw experience, the substance of direct
awareness, but we have other strong intuitions, some turn out true and others
false. We have an intuition that space is necessarily flat, an intuition proven
false only with non-Euclidean geometries in the 19th century. We
have an intuition that every event has a cause, which determinists believe but
indeterminists deny. Sequestered intuitions aren’t knowledge.
B. Experience can’t reveal the error in the intuition that raw experience exists.
To correct wayward
intuitions, we ordinarily test them against each other. A simple perceptual
illusion illustrates: the popular Muller-Lyer
illusion, where arrowheads on a line make it appear shorter than an
identical line with the arrowheads reversed. Invoking the more credible
intuition that measuring the lines finds their real length convinces us of the intuitive
error that the lines are unequal. In contrast, we have no means to check the truth of the
belief in raw experience; it simply seems self-evident, but it might seem
equally self-evident if it were false.
C. We can’t capture the ineffable core of raw experience with language because nothing's really there.
One task in
philosophy is articulating the intuitions implicit in our thinking, and sometimes
rejecting the intuition should result from concluding it employs concepts
illogically. What shows the intuition of raw experience is incoherent
(self-contradictory or vacuous) is that the terms we use to describe raw
experience are limited to the terms for its referents; we have no terms to
describe the experience as such, but rather, we describe qualia by applying terms denoting
the ordinary cause of the supposed
raw experience. The simplest explanation for the absence of a
vocabulary to describe the qualitative properties of raw experience is that
they don’t exist: a process without properties is conceptually vacuous.
D. We believe raw experience exists without detecting it.
One error
in thinking about the existence of raw experience comes from confusing
perception with belief, which is conceptually distinct. When people universally
report that qualia “seem” to exist, they are only reporting their beliefs—despite
their sense of certainty. Where “perception” is defined as a nervous system’s
extraction of a sensory-array’s features, people can’t report their perceptions
except through beliefs the
perceptions sometimes engender: I can’t tell you my perceptions except by
relating my beliefs about them. This conceptual truth is illustrated by the
phenomenon of blindsight, a condition in which patients report complete blindness yet, by discriminating external
objects, demonstrate that they can perceive them. Blindsighted patients can report only according to their beliefs, and they perceive more than they believe and report that they perceive. Qualia nihilism analyzes the intuition
of raw experience as perceiving less
than you believe and report perceiving, the reverse of blindsight.
3. The conceptual economy of qualia nihilism pays off in philosophical progress.
Eliminating
raw experience from ontology produces conceptual economy. A summary of its
conceptual advantages:
A. Qualia nihilism resolves an
intractable problem for materialism: physical concepts are dispositional, whereas raw
experiences concern properties that seem, instead, to pertain to noncausal
essences. If raw experience was coherent, we could hope for a scientific
insight, although no one has been able to define the general character of such
an explanation. Removing a fundamental scientific mystery is a conceptual gain.
B. Qualia nihilism resolves the
private-language problem. There
seems to be no possible language that uses nonpublic concepts. Eliminating raw
experience allows explaining the absence of a private language by the
nonexistence of any private referents.
C. Qualia nihilism offers a compelling
diagnosis of where important skeptical arguments regarding the possibility of
knowledge go wrong.
The arguments—George Berkeley’s are their prototype—reason that sense data,
being indubitable intuitions of direct experience, are the source of our
knowledge, which must, in consequence, be about
raw experience rather than the “external world.” If you accept the existence of
raw experience, the argument is notoriously difficult to undermine logically
because concepts of “raw experience” truly can’t be analogized to any concepts
applying to the external world. Eliminating raw experience provides an elegant demolition; rather than the other way around, our belief in raw
experience depends on our knowledge of the external world, which is the source
of the concepts we apply to fabricate qualia.
4. Relying on brute-force intuition is rationally specious.
Against
these considerations, the only argument for retaining raw experience in our
ontology is the sheer strength of everyone’s belief in its existence. How much
weight should we attach to a strong belief whose validity we can't check? None.
Beliefs
ordinarily earn a presumption of truth from the absence of empirical challenge,
but when empirical challenge is impossible in principle, the belief deserves no
confidence.
[Overlaps 16.0 The supposedly hard problem of consciousness and the nonexistence of sense data: Is your dog a conscious being? The present essay is comparatively more sequential, as opposed to global.]
[Overlaps 16.0 The supposedly hard problem of consciousness and the nonexistence of sense data: Is your dog a conscious being? The present essay is comparatively more sequential, as opposed to global.]