From: "Marshall Feldman" <marsh-AT-URIACC.URI.EDU>
Subject: RE: BHA: RE: Causal powers of absence - and reductionism?
Date: Mon, 29 Jun 1998 08:17:43 -0400




> Let's go back to the hole in the ozone layer. Considered as
> an absence the
> hole can be properly said to be part of the causal complex
> that leads to
> increses in skin cancer. It could be that I need to go back
> and read RTS
> again, but I always thought a realist account of cause
> recognised that in
> open systems multiple mechanisms are in play. Gunpowder is an
> example often
> used. Gunpowder has the power to explode, but it needs
> igniting. A realist
> account of cause doesn't locate the cause of igniting gunpowder in the
> power of the gunpowder to ignite but in the causal complex
> which leads to
> ignition. Gunpowder alone does not ignite.  The same can be
> said of the
> suns rays; they have the power to cause skin cancer, yet this
> power isn't
> always realised. The specifics of why and when it is realised
> depend upon
> the situation. And in terms of global warming the hole in the
> ozone layer
> plays its role (a causal role) in letting more rays through.
> This, if you
> want to put it this way, is the power the hole in the ozone
> layer possesses
> - the power to let rays through. Of course we can always describe this
> situation differently, but I don't see what hangs on this, we
> can describe
> everything differently. The mere possibility of a different
> explanation
> doesn't refute the first explanation.

I think the point I was trying to make was a bit more specific. For the
examples that have been given here, at least, there is always a positive
explanation relying on presence corresponding to negative one relying on
absence. The question then becomes, why burden the discussion with the
difficult, controversial, and perhaps obscure notion of absence?

Examples of specific positive explanations:

	1) Ozone layer: The atmosphere, consisting mainly of nitrogen, oxygen, and
water vapor, creates an ozone layer that filters the sun's rays. "Raw"
(unfiltered) rays from the sun have the power to increase the likelihood of
skin cancer. Since the industrial revolution, human practice has generated
various pollutants that have depleted the ozone layer.

	2) Gunpowder: An open flame has the power to ignite gunpowder. Gunpowder
has the innate causal power of being able to explode, and an open flame has
the innate causal power of being able to release gunpowder's innate power of
exploding.

I'm not debating that we can describe these things in terms of absence.
Instead, I'm asking:

	1) What does "absence" as a mode of description if we can always do without
it.
	2) "Absence" seems to point to an infinite set. For example, with the ozone
layer we have at least four other absences (a) industrial pollution that can
serve as a substitute filter, (b) the sun cooling down and having less
damaging impacts, (c) a set of space stations attached to large wooden
"umbrellas" that shield the earth from the sun's rays coming through the
"hole," and (d) sunflowers. Some of these are quite relevant, others quite
irrelevant. Since the set is infinite, how do we in fact identify relevant
absences? And, when we do, aren't we tacitly alluding to the positive
properties of the absent entities?

>
> Why do I think the spectre of reductionism is looming?
> Because the attempt
> to understand increased rates of skin cancer purely in terms
> of the active
> causal mechanism is apt to miss the causal complex which
> provides a fuller
> account. At a biological level it is clearly the increased
> exposure of the
> suns rays which are responsible, but to fully understand this
> situation we
> would need to incorporate more levels into our explanation,
> one of which
> would be the environment. Clearly, there is something present in the
> environment which is causally implicated in increased rates
> of skin cancer.
> And this thing is a hole in the ozone layer - some of the
> ozone layer is
> absent. At the level of the environment there is a hole in
> the ozone layer
> letting in more rays. This hole by itself doesn't explain
> increased rates
> of skin cancer any more than the mere existence of matches explains
> igniting fireworks, but without it these increased rates can't be
> explained, any more than igniting fireworks can be explained without
> recourse to mechanisms of ignition.

I don't think complexity is the issue. You're right. Clearly explanations
based solely on the causal properties of the sun's rays or fireworks'
explosive powers are inadequate. The questions I'm raising are (1) what
constitutes an adequate explanation (i.e., When do we stop listing things
from the infinite set of things that are absent? How do we order the things
we do list? How do we relate them to each other? Would an alternative
explanation in terms of presences be as good? etc.) and (2) is "absence"
anything more than a linguistic expression and does it deserve special
status as an ontological category (since what makes a specific absence
relevant always depends on causal properties of specific presences)?



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