Date: Sat, 27 Jun 1998 14:12:48 +0100
From: Colin Wight <Colin.Wight-AT-aber.ac.uk>
Subject: Re: BHA: RE: Causal powers of absence - and reductionism?


I've still yet to hear a half decent argument as to why it is incorrect to
say 'the absence of water causes dehydration'. Anyway, it seems to me that
some of the arguments about absences and causation might be straining at
the leash of reductionism. 

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. 

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.

Cheers,


============================================

Dr. Colin Wight
Department of International Politics
University of Wales, Aberystwyth
Wales
SY23 3DA
Tel: (01970) 621769 


     --- from list bhaskar-AT-lists.village.virginia.edu ---