On 27/04/2017 12:45 am, Telmo Menezes wrote:
On Wed, Apr 26, 2017 at 2:04 PM, Bruce Kellett
The issue at stake here appears to be whether arithmetic (and mathematics)
can be derived form physics, or has to have some non-physical origin. As I
said to Bruno a short time ago, the derivation of this result is
epistemological rather than logical. In other words, there is no formal
proof, but rather an observation as to how things actually happen in
practice. We just have to consider how a baby learns numbers -- by
interacting with physical objects, be they play blocks with pretty pictures
and number on them, or be they just stones in the yard. By manipulating
physical objects, we learn about numbers, and the rules that govern them.
Similarly, geometry and trigonometry arose from the necessity to measure
plots of land for competing landowner interests. Mathematics is, at base, an
intensely practical subject that arises out of our experience of the
physical world.
The formalization of mathematics into an abstract system follows much later
from this initial epistemological encounter.
I can understand how this epstemological model can lead to the
intuition that mathematics is a "by-product" of physics, but I have a
hard time accepting that it is more than an intuition.
Put the question another way. If we do not develop our understanding of
arithmetic in this epistemological way, how do we get the concept of number?
I can't help but feel that looking at the history of human thought, the
understanding of number, and the development of sophisticated
mathematics, were hard-fought victories. These things were not obvious,
and had to be worked for over time as humanity sought to formalize its
interactions with the world. The development of mathematics went along
with the development of physical understanding -- sometimes one led,
sometimes the other -- but mathematics only became an abstract study,
apparently divorced from physical experience, only relatively recently
in human history.
I am not arguing that this is not the case, but I am arguing that you
have nothing more than an intuition. I don't think it is valid to
infer that X supervenes on Y because humans learn about X from
studying Y.
I don't think that is the argument. We say that consciousness supervenes
on the physical brain because there is an observed two-way
interdependence between consciousness and the brain. We learn about this
interdependence by studying both consciousness and the brain.
I can even offer a third option (which I don't bet on): math (and even
physics) are just properties of how our brains are wired by evolution
to perceive reality.
The idea that consciousness supervenes on the physical brain is, again, an
idea that arises from experience. We experience the effects of drugs such as
alcohol on our brain, and the corresponding effects on consciousness. We are
aware of the consequences of brain injury, strokes, concussion, neurological
degeneration, and so on. So the idea that consciousness supervenes on the
physical brain is not in any way controversial. If changes to the brain
affect consciousness in such a direct way, it is natural to conclude that
consciousness is associated with brain states, or, more formally, that
consciousness supervenes on the physical brain.
Ok, I think you have more or less the same position as Brent on this.
I think so, though Brent often explains it better than I do.
In my view, this type of argument uses "consciousness" with different
meanings. When I say consciousness I don't mean it in the sense of
"state of consciousness". In the latter case, I see "being drunk" as
part of the environment you are perceiving, if you allow me to include
your own brain in what I call the environment.
What I refer to as "consciousness" is merely the fact that
first-person experience of reality is possible. I claim this is a
binary property: either it exists or it doesn't. For this thing that I
am referring to, it is irrelevant how close the experiences being
perceived are to a possible external reality.
But then you have consciousness as an abstract type -- it is not
consciousness of something. I do not think that any such abstraction has
independent existence. It is not that there is "consciousness" and
various things flow through it. In the absence of something to be
conscious of, there is no consciousness. As Brent has pointed out,
sensory deprivation experiments tell us something about this: in the
absence of stimuli (something to be conscious of), the brain goes into a
loop and the person ceases to be actively conscious. Similarly, under
anaesthesia, external stimuli are removed and the person loses
consciousness. Something similar happens in sleep, but to a lesser
extent since it seems that some part of the subconscious is still aware,
to some extent, of its surrounds. So the experience of alterations in
the conscious state occasioned by changes in the brain is direct
evidence for the supervenience of consciousness on the physical brain.
This conclusion is strengthened by studies of the inverse -- changes in
the conscious state induce changes in the brain, as evidenced by MRI
studies, PET scans, and the like.
A philosophical zombie, wired in the same way as our brain is, could
have its behaviour influenced by the mechanical effect of alcohol
molecules in its neural network in the same way that we are. But why
is there an internal observer? What is that thing? This is the hard
question.
I doubt that a philosophical Zombie is possible. If something acts the
way a person does, responds to stimuli in the same way, and can hold an
intelligent conversation, what criterion could you use to say that it is
not conscious?
Bruce
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