Churchland, science, prediction, etc.

John McCreery (JLM@TWICS.COM)
Sat, 16 Sep 1995 11:45:42 +0900

The following is No. 2 in a series of postings motivated
by reading Patricia Churchland's _Neurophilosophy:
Toward a unified science of the mind/brain_. As I
noted previously, Churchland is concerned to
overcome what she sees as an unwarranted split
between neurobiology and cognitive

To many of our colleagues, the word "science" is, like
the Matador's cape to the bull, an invitation to charge.
Some are appalled by the search for mechanical
explanations that, to them, to violate deep human
concerns. Others charge in defense of "science," with
banners labeled "facts" and "objectivity" tied to their
horns. Both, it seems to me, are blinded by a dated
positivist/logical empiricist view of science and a
failure to attend to what it is that scientists actually
do. One of Churchland's greatest strengths is the clarity
with which she interprets the history of science and
the skill with which she draws implications from how
science is practiced.

Consider the curious notions conveyed by the word
"fact." A commonsense view of its meaning suggests
that human beings have, at least some of the time, (we
leave aside obvious cases of fraud, deception, illusion,
ideology) an instantaneous and unmediated access to
reality. I point, you see, we then agree on an
"undeniable" "fact." Neurological evidence shows
clearly that the idea of "instantaneous and unmediated
access to reality" is, in itself, a chimera.

I now quote from Churchland,

"Helmholtz [Heinrich von Helmholtz, 1821-1894] then
tested Muller's claim that nerve impulses traveled at
immedasurable speeds. His methods were elegantly
simple and quantitative. He measured the velocity of
nerve conduction by stimulated the nerve at different
points and noting how long it took for the muscle to
contract. He found, to great amazement, that is was
slower even than the speed of sound." In his
preparation he calculated conduction velocity at a
mere thirty meters per second."

Helmholtz's father found these results rather shocking.
In a letter to his son he wrote,

"....the results at first appeared to me surprising, since
I regard the idea and its bodily expression not as
successive but as instantaneous, a single living act that
onllybecomes bodily and mental on reflection, and I
could as little reconcile myself to your view as I could
admit a star that had disappeared in Abraham's time
should still be visible."

We now know, of course, that since light, too, travels at
a finite speed, that star is altogether possible.

Helmholtz' research added a new temporal dimension
to research that had already shown that the brain
constructs its image of the world and does not directly
perceive it.

"Charles Bell (1774-1842) pioneered experimental
research into the cause of differences in sensory
qualities. By poking himself smartly on the tongue
with a sharp needle, he noticed that for some areas he
could elicit a sensation of pain, but for others he could
elicit no pain whatever, but only a slightly metallic
taste. Despite the identity of the stimulus, the effect
was markedly different, and this moved Bell to believe
that the difference was due to the nerves or to the
brain and not to the nature of the stimulus."

The Muller whose work Helmholtz challenged had
already concluded that,

"...sensation is not the conduction of a quality or state
of external bodies to consciousness, but a conduction of
a quality or a state of our nerves to consciousness,
excited by an external cause."

Facts, it appears, are made not found. Which is why, I
suppose, scientists are obsessive about their methods
and casual observation does not count as science.

John McCreery
Saturday, September 16, 1995