Think: A Compelling Introduction to Philosophy by Simon Blackburn Page A

rationalism. Still, when we try to think hard
about the relationship between brain and body on the one hand
and mind on the other, it usually seems to he our thinking rather
than mere scientific ignorance that is letting us down. Recently many scientists have turned their attention to consciousness, and a
variety of brain states have been identified as implicated in normal
conscious functioning. For example, electromagnetic waves in the
brain of a particular low frequency have been thought to be vital.
But it is not clear that this kind of truth is adapted to solving the
problem-to enabling us to side with Leibniz against Locke. From
the Lockean point of view, all the scientist may have discovered is
that when the brain is in some specific state, we get symptoms of
consciousness. But that might just tell us what consciousness is annexed to, by happenstance. It does not make the combination intelligible. And it also presupposes a right to shove the Zombie and
Mutant possibilities out of sight, for otherwise the scientist could
never establish the correlation, except at best in his or her own case.
But according to new mysterians, neither science nor philosophy
will ever get us to a point where things are better. We will never be
able to side wholeheartedly with Leibniz against Locke.

    INVERTED SPECTRA: PRIVATE
LANGUAGES
    The case of colour often seems especially to open wide the possibility at least of Mutants-people physically identical who nevertheless perceive colours quite differently. There might even be
Mutants whose colour spectra are completely inverted with respect to each other, so that the experience one gets from light at the
red end of the spectrum is the very experience that the other gets from light at the blue end. And there would be nothing to tell them
that this is so.

    Cartesian dualism opens the possibility of Zombies and Mutants. But perhaps it also opens an even more frightening possibility. If we think in the dualist way, we are apt to feel secure that at
least we know what our own experience is like. The minds of others may he a hit conjectural, but our own minds are well known to
us. But is even this true? Consider now not the minds of others, but
your own past experience. Are you sure that the world looks to you
today the same colour as it looked yesterday? Are you in fact sure
that it looked any colour yesterday-in other words, that you actually received the conscious experience that you remember yourself
as having had?
    By asking these questions you are applying the Zombie and Mutant possibilities to your own past. Now of course, at first sight the
possibilities are even more outlandish and absurd than applied to
other minds. And we are inclined to retort that of course we know
perfectly well that colours looked much the same yesterday as they
do today. We would surely notice it if we woke up and the sky now
looked like grass did yesterday, and vice versa.
    I agree of course that we would notice the change. But is this security guaranteed, given Cartesian dualism? It depends on what we
think about memory and mental events. Why should we be sure
that mental events-thought of as entirely distinct, remember,
from anything physical-leave reliable traces in memory? I can
check that my memory of the physical world is reliable enough. I
remember putting the car in the garage, and lo and behold, when I
go down, there it is. I remember the way to the kitchen, and lo and behold, get there without any effort or any mistake. But what
would check that my memory of the mental world is accurate? In
Locke's terms, why should it not be `God's good pleasure' to annex
certain mental modifications to me today, together with the delusive memory that similar ones were annexed to me yesterday?
Wittgenstein said:

    Always get rid of the idea of the private object in this way: assume that it constantly changes, but that you do not notice the
change because your memory constantly