Descartes here is making a case for an immortal soul
exclusive to humans. His argument is that nonhuman animals are unthinking
machine-like things (so much so that they could be replaced with machines and everyone
would be none the wiser) whereas we humans are unique due to our reason and
souls. He says that other animals are only moved by passions or impulses, and
that even when they are very good at imitating us or doing tricks for us, it is
only out of fear or the desire for a treat, not thinking. He does not deny the
existence of life or sensations in these lesser automatons, and even admits to
their being better than us at some things, such as in physical strength or
ability, but says that these do not support the existence of an immortal soul,
and perhaps even strengthen his own argument. For Descartes, to be human is to
use real speech, which he defines as “indicating by word or sign something relating
to thought alone and not to natural impulse.”
Descartes lived and wrote in a time before robots, artificial
intelligence, neuroscience and extensive animal behavior studies, and in
working with what he had came up with good and sound ideas. He even seems to foreshadow
the phenomenon of the “uncanny valley,” that feeling of unease at something very
close to being human (as in, robot puppies are cute, but the robots in “I,
Robot” kind of freak people out). However, without turning this into some
research paper here, I’m not sure that what he says holds quite so true today.
Some animals seem to show some inklings of intelligence or consciousness, even
if quite removed from our own in terms of any sort of ranking system as
Descartes points out. Sure, I guess that dolphins playing or having sex for fun
can be attributed to nothing more than their urges, but then when you start to
look into some experiments with great apes and even parrots, the idea that all
nonhuman behavior is some conditioned response grows less convincing. Koko the gorilla
learned to sign hundreds of words to express thoughts, even creating her own
signs and communicating seemingly without hope of some immediate reward such as
food. Alex the African Grey parrot is said to have shown the intelligence of a
five year old human in terms of recognizing objects by identity, shape, color,
and so forth; was beginning to learn phenomes; and created his own word
combinations similarly to Koko. Whether these behaviors by these animals would
warrant Descartes to say they indicate the presence of souls is debatable, and
to what extent they express some consciousness is a point of a good bit of contention
among scientists today. Consciousness is definitely weird, and you can’t blame someone,
especially from a time such as Descartes’ (pre-Darwin and all), in thinking
that it makes our species special. We are unique, but whether we are better is
more than debatable.