An Evening at the Cartesian Theatre
25
as something totally different, and vision as something different again. Vision
acts on us in a special way that was discussed earlier, under the heading “A
Necessary Deception”. We project the scene our brain has constructed back
onto the world, and therefore witness it there, where we believe it should be.
For that reason, we are unshakably convinced that we aren’t merely seeing an
image of the world, but are right in it and perceive it directly, as it is.
This self-deception is a biological imperative. It tricks us into the belief that
we get more from our eyes than merely a representation of reality: We believe
that what we get is the real thing—reality itself! This belief is the basis of a
philosophical ideology called Direct Realism. Part of its staying power is that
even if you have philosophical doubts about direct realism, you are obliged to
go about your daily activity as if you believed in it.
In direct realism, the observer is an innocent spectator, and plays no role in
shaping reality. Even though this belief is overwhelmingly supported by common sense, it turns out to be false. All of modern science, from fundamental
quantum physics up to cognitive psychology, points to a fundamental, constitutive link between the observer and reality. To understand why this is so,
it is instructive to try to imagine what the universe is like independently of all
observation.
Let’s carry out a thought-experiment: Imagine that all life has vanished from
the universe, but everything else is undisturbed. Matter is scattered about in
space in the same way as it is now, there is sunlight, there are stars, planets and
galaxies—but all of it is unseen. There is no human or animal eye to cast a
glance at objects, hence nothing is discerned, recognized or even noticed.
Objects in the unobserved universe have no shape, color or individual
appearance, because appearances are created by minds. They do not have features, because almost every feature you can think of corresponds to a category
of animal sensation. It has been claimed, for example, that the very notion of
solid matter rests on the sensation of hardness. We assign qualities to objects
according to the way they affect our senses. In other words, it is our sense
organs, and their extensions in the brain, that create features and qualities.
Thus, in a universe without sentient beings, all features and appearances are
absent.
Philosophers refer to a universe of this kind as the mind-independent universe, or as I’ll call it here, the primal universe. It is not a universe of science
fiction, because there was a time in prehistory when life had not yet evolved,
and the universe was as we have just imagined it. By definition, then, the
primal universe is the residue after all sensable qualities have been taken away.
(Sensable qualities are those which can be sensed by living creatures.) It is this
universe that the physical sciences strive to understand.
25
as something totally different, and vision as something different again. Vision
acts on us in a special way that was discussed earlier, under the heading “A
Necessary Deception”. We project the scene our brain has constructed back
onto the world, and therefore witness it there, where we believe it should be.
For that reason, we are unshakably convinced that we aren’t merely seeing an
image of the world, but are right in it and perceive it directly, as it is.
This self-deception is a biological imperative. It tricks us into the belief that
we get more from our eyes than merely a representation of reality: We believe
that what we get is the real thing—reality itself! This belief is the basis of a
philosophical ideology called Direct Realism. Part of its staying power is that
even if you have philosophical doubts about direct realism, you are obliged to
go about your daily activity as if you believed in it.
In direct realism, the observer is an innocent spectator, and plays no role in
shaping reality. Even though this belief is overwhelmingly supported by common sense, it turns out to be false. All of modern science, from fundamental
quantum physics up to cognitive psychology, points to a fundamental, constitutive link between the observer and reality. To understand why this is so,
it is instructive to try to imagine what the universe is like independently of all
observation.
Let’s carry out a thought-experiment: Imagine that all life has vanished from
the universe, but everything else is undisturbed. Matter is scattered about in
space in the same way as it is now, there is sunlight, there are stars, planets and
galaxies—but all of it is unseen. There is no human or animal eye to cast a
glance at objects, hence nothing is discerned, recognized or even noticed.
Objects in the unobserved universe have no shape, color or individual
appearance, because appearances are created by minds. They do not have features, because almost every feature you can think of corresponds to a category
of animal sensation. It has been claimed, for example, that the very notion of
solid matter rests on the sensation of hardness. We assign qualities to objects
according to the way they affect our senses. In other words, it is our sense
organs, and their extensions in the brain, that create features and qualities.
Thus, in a universe without sentient beings, all features and appearances are
absent.
Philosophers refer to a universe of this kind as the mind-independent universe, or as I’ll call it here, the primal universe. It is not a universe of science
fiction, because there was a time in prehistory when life had not yet evolved,
and the universe was as we have just imagined it. By definition, then, the
primal universe is the residue after all sensable qualities have been taken away.
(Sensable qualities are those which can be sensed by living creatures.) It is this
universe that the physical sciences strive to understand.