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Sophie Rand

Student Engineering, The Cooper Union For The Advancement of Science and Art


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Can we ever know how another person "senses" the world?

In my Bioelectricity class this week, we learned about the cells
in our body that help us sense our environment: chemosensors in our
tongue that help us sense taste, for example, the photoreceptors in
our eye that sense light, and the hair cells in our ears that sense
the mechanical vibrations of sound, to name a few.

As a result, I recently revisited my answer to the age-old question of
“how do I know that the blue I see is the same blue you see?” that was
so startling and exciting to most 3rd graders playing baby Kierkegaard
a little bit differently. An answer could be that we just have to
trust that perception is guided by biology and that humans are
biologically identical to within 80% of our biological systems.

This answer, of course, raises new questions: even if you and I may
perceive the same blue, is that blue "real?" Where does sensation
leave off and perception begin, and how may we trust ourselves as we
try to compare them? Can we ever know how another person "senses" the
world? Would love to hear your thoughts!


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  • Feb 22 2012: My comment below suggested that we naturally relate our perception to events in the real world - real events such as being in a dark room or having our optic nerve cut affect our vision. It is now generally assumed that ALL details of our perception can be related to mechanisms/events in the real.
    We confront the mind-body problem in this understanding if we try to superimpose the experience of seeing something with the mechanism by which we suppose this seeing to occur. The problem is solved easily - quite simply, both are expressed in terms of our own perception: - we invariably get a mind body problem if we try to insert our experience as an entity into the real world (which is itself expressed in terms of our own perception). The mind body problem amounts to trying to put experience into itself.

    If perception is about mechanism then we naturally suppose that if we replace the mechanism a tiny piece at a time we could theoretically replace the entire mechanism without altering perception. But we understand that the body itself actually does this at least to some extent. Whether parts can be replaced by different materials is moot - it is doubtful that a silicon based perceiver could be equivalent to a carbon based one.

    Can we integrate mechanisms to experience as others experience? One would expect that it depends on how modular the perception is. I would guess that seeing something as I do and then seeing it as you do is NOT like looking from one painting to another. Our visual perception is vastly more complex than the immediate electromagnetic input. I would guess that a mechanism that is capable of remembering and comparing two sets of visual experience is vastly more complex than what we ourselves possess. I would guess that this problem of comparison applies even to ourselves from a time significantly in the past i.e. our identity is recognizable (to ourselves and others) only because it does not change very quickly (an issue related also to mechanism).

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