David asked: ‘Why do you
say that consciousness has to be non-corporeal?’
In my third answer I shall
once again begin with Aristotle, this time contrasting the physical time of the
Physics with the one-ness of time in the
De Anima (On the Soul). In the Physics
Aristotle defines time as the ‘before and after’ of movement in space, which
can be measured and numbered.
In principle, this is how
neurophysiology studies and depicts neural processes, relating them to time
measured in milliseconds. Let me quote from Carpenter and Reddi’s Neurophysiology: ‘If we know the
time-course of the permeabilities [of the nerve cell membrane] we should be
able to calculate … the time-course of the action potential itself (p. 30-31) …
If we try to stimulate a nerve with a pair of shocks, gradually reducing the
interval of time between them … This period, during which it is impossible to
stimulate the nerve for a second time, is known as the absolute refractory
period (p. 33) … rapid depolarizations [of the nerve cell membrane] are more
effective than slow ones, because they get at sodium as it were before
potassium has time to rise … Sodium is quick on the draw, but quickly gives up
and in fact keels over altogether because it gets inactivated … potassium rises
slowly but inexorably to its final value (p. 34) … In nerves, information is
mostly coded by the frequency of firing … temporal codes … when action
potentials finally reach the end of the axon they open voltage-gated channels,
which let calcium in. This then makes the terminal release the transmitter it
contains from the vesicles in which it is normally stored. Since each spike is
identical, it releases the same quantity of transmitter; consequently altering
the frequency causes the rate of transmitter release to change, so that the
original information is passed on to the target cell (p. 38-39) …
***
In the De Anima Aristotle notes that we
discriminate between sensory perceptions of different sensory organs – when we
consider a sugar cube, we are aware that its being sweet is different from its
being white – and that this discrimination must be perceived by an agency that
is one and undivided, in undivided time (hȏste achȏriston kai en achȏristȏi chronȏi,
426b22-29). Aristotle used the sweet and the white as examples, but he could
have used the ‘before and after’, which he views as constitutive of our
perception of time in the Physics,
for from the point of view of the De Anima the past is perceived as different from
the future in the undivided present.
The
most remarkable aspect of Aristotle’s reflections on time in the Physics is the absence of the present:
time is composed (sunkeitai) of the
part that has been (to men oun autou
gegone) and is not (kai ouk estin),
and of the part that is going to be (to
de mellei) and is not yet (kai oupȏ
estin, 217b33-218a2). The ‘now’ (to
nun) plays an important role in his deliberations about time, ‘but it is
not a part of time’ (to de nun ou meros,
218a6); it demarcates time as the body that moves demarcates movement: “The
‘now’ follows the body carried along (tȏi
de pheromenȏi akolouthei to nun), as time follows motion (hȏsper ho chronos têi kinêsei), for we
gain knowledge of the ‘before and after’ in motion by means of the body carried
along (tȏi gar pheromenȏi gnȏrizomen to
proteron kai husteron en kinêsei), and the ‘now’ is (to nun estin) in so far as the ‘before and after’ is countable (hêi arithmêton to proteron kai husteron,
219b22-25).
Biochemical
and bioelectrical processes studied by neurophysiology proceed in a space-time
continuum outlined by Aristotle in his Physics.
In the De Anima Aristotle views the ‘now’ very differently: ‘For just as
the one and the same says that the good and the bad is different (hoti heteron to agathon kai to kakon),
so also when (hote) it says that the one is different and the other is different
[must be one and undivided], the when
is not accidental (ou kata sumbebêkos to
hote)… the undivided one says thus (all’
houtȏ legei) both now and that now (kai nun kai hoti nun), together therefore (hama ara, 426b24-28).
The present comes into its own in Aristotle’s Rhetoric: ‘All that is pleasurable (panta ta hêdea) must be (anankê) either present in being actually
perceived (ê en tȏi aisthanesthai einai
paronta) or in being remembered as past (ê en tȏi memnêsthai gegenêmena) or in being hoped for as coming in
future (ê en tȏi elpizein mellonta).
For people perceive the present pleasures (aisthanontai
men gar ta paronta), remember the past ones (memnêntai de ta gegenêmena), and hope for the pleasures to come (elpizousi de ta mellonta, 1370a32-35).’
The present is here reflected by Aristotle as the primary field of experience,
the past and the future come into view in
the present as memories or expectations.
***
The
psycho-somatic effects of the interplay between the past, present and future can
be studied on animals. Let me quote Carpenter and Reddi’s Neurophysiology: ‘Consider a classic example: Pavlov’s famous
experiments with dogs … A dog is trained by frequent association of sound and
food to salivate when a bell is rung. Since he didn’t do it before, there must
have been a change in his neural connections … What we observe is that after
sufficient pairings of food with bell, the bell alone eventually produces
salivation … What it amounts to is fire
together, wire together: neurons representing things that tend to happen
together get physically linked together, so that brain eventually embodies a
model of the outside world.’ (p.258)
In
the ‘Self-knowledge as an imperative’ on my website I wrote: ‘Pace Carpenter and Reddi, in Pavlov’s
experiments, as far as I can remember, the conditional stimulus preceded the
unconditional stimulus; Pavlov engineered varied gaps between the two … The
authors write that fire together, wire
together “is the secret of cerebral cortex: it provides a mechanism for
creating physical connections between neurons that are often active
simultaneously.” But the neural mechanism of fire together, wire together
cannot explain Pavlov’s experiments on dogs, let alone constitute a model of
the outside world in the brain.’
I
have looked at the Wikipedia entry on Pavlov’s experiments on dogs; there the
conditioning I remembered from my reading Pavlov (some 57 years ago) is called
trace conditioning. I remember most vividly Pavlov’s experiments with visual stimuli,
which allowed him to observe the dog’s ability to discriminate between different
figures flashed on a screen: A circle appears on the screen, a time interval,
food. When the conditional reflex has been established, the circle is followed
by no food, but an ellipsis on the screen is followed by food; the dog learns
to differentiate between the two.
Pavlov’s
experiments can be viewed in terms of the interplay between the past, present,
and future. When the conditional reflex has been established, the present
picture of a circle is perceived by the dog as an indication of the future,
food is to come. When the circle ceases to be followed by food, it is followed
by the discomfort caused by the digestive juices produced by the stomach; when it
subsequently ceases to evoke any response, the past experience has affected the
dog’s present.
Who
owns a dog can make such experiments with a lot of fun. You throw your dog a
ball. The dog runs to retrieve it. You pretend to throw the ball, the dog runs
after it, but it remains in your hand.
After a few such futile attempts, the dog sits and watches you, its eyes
full of expectation. If you go on disappointing it, it ceases to be interested,
leaves you and does its own business.
***
The interplay between the present,
past and future acquires a new level of intricacy and intensity thanks to our
use of language. Consider a sentence from Kant’s Critique of Pure Reason, which I am borrowing from my last post
devoted to Kant, ‘Ethical
considerations concerning Kant’s transcendental ideality of space and time’,
posted on August 27. In the post the sentence is abbreviated and translated by
me; now I am bringing it in full in Meiklejohn’s translation: ‘Suppose now, on the other hand, that we have undertaken this
criticism (Wenn aber die Kritik nicht
geirrt hat,), and have learnt that an object may be taken in two senses, (da sie das Objekt in zweierlei Bedeutung nehmen lehrt), first, as a
phenomenon (nämlich als Erscheinung,), secondly, as a thing in itself (oder als Ding an sich selbst;); and that, according to the
deduction of the conceptions of the understanding (wenn die Deduktion ihrer Verstandesbegriffe richtig ist), the
principle of causality has reference only to things in the first sense. We then
see how it does not involve any contradiction to assert, on the one hand, that
the will, in the phenomenal sphere – in visible action, is necessarily obedient
to the law of nature, and in so far, not
free; and, on the other hand, that, as belonging to a thing in itself, it
is not subject to that law, and, accordingly, is free. (mithin auch der
Grundsatz der Kausalität nur auf Dinge im
ersten Sinne genommen, nämlich sofern sie
Gegenstände der Erfahrung sind, geht, eben dieselben aber
nach der zweiten Bedeutung ihm nicht unterworfen sind, so wird eben derselbe
Wille in der Erscheinung (den sichtbaren Handlungen) als dem Naturgesetze
notwendig gemäss und sofern nicht
frei, und doch andererseits, als einem Dinge an sich selbst angehörig, jenem nicht unterworfen, mithin als frei, gedacht,
ohne dass hierbei ein Widerspruch vorgeht. B XXVII-XXVIII).
All this is one sentence in German; as
you read it word by word, phrase by phrase, it sinks from the narrow straits of
the conscious presence into the subconscious, yet in the subconscious it is all
the time present, and in the interplay between the subconscious and the
consciousness a nonverbal understanding of the sentence is growing, until it
culminates when you reach the end of the sentence. If you then read
Meiklejohn’s very free paraphrase, divided into two sentences, it may help you
understand better the underlying German original, and Kant’s German may help
you understand what Meiklejohn has done with it in his paraphrase. In doing all
this, the time goes by, but your effort to understand Kant’s thought transcends
the passing of time in the undivided presence (undivided into the Aristotelian
‘before and after’, the past and the future) of ever intensified understanding.
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