Atheism and Theism JJ Haldane - Common Sense Atheism
Atheism and Theism JJ Haldane - Common Sense Atheism
Atheism and Theism JJ Haldane - Common Sense Atheism
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128 J.J. <strong>Haldane</strong><br />
as caused by that kind of agency; <strong>and</strong> second, those in which the argument<br />
is from effects to a cause, itself then characterized simply as that which is<br />
their source. Aquinas calls these demonstrations ‘propter quid’ (showing why)<br />
<strong>and</strong> ‘quia’ (showing that) respectively; <strong>and</strong> he then goes on to write that ‘The<br />
truths about God which St Paul says we can know by our natural powers of<br />
reasoning – that God exists, for example – are not numbered among the<br />
articles of faith, but are presupposed to them’ (Summa Theologiae, Ia, q. 2, a.<br />
2 ad. 1).<br />
Propter quid arguments are very familiar in the sciences <strong>and</strong> in everyday<br />
causal reasoning. Suppose you notice a mark etched in the surface of a piece<br />
of furniture <strong>and</strong> ask how it came about. Someone then points out that a glass<br />
of whisky was previously lying there <strong>and</strong> explains that some must have spilt<br />
<strong>and</strong> caused the stain due to the solvent power of its alcohol. The explanation<br />
proceeds from a known cause to one of its effects showing why the effect<br />
exists. By contrast consider the following case. Some while ago I noticed that<br />
the electrical shower at home was running at a much higher temperature than<br />
previously. This was a problem since it had become too hot to use, <strong>and</strong> so,<br />
although I had no illusion that I could repair it, I did set to wondering why<br />
the temperature had increased. The water was hotter <strong>and</strong> the flow was less;<br />
<strong>and</strong> given the way in which electric showers operate – by running the incoming<br />
cold water over an electrically heated element – these two factors seemed<br />
likely to be connected. This phase of the reasoning was in part a case of<br />
inference propter quid (inferring the increased heat from a knowledge of the<br />
causal mechanism). What followed, however, was a demonstration quia; for<br />
having reasoned that the temperature increase was due to reduced water flow<br />
<strong>and</strong> having checked from other outlets that the water pressure elsewhere in<br />
the house was normal, I inferred that there must be a partial blockage somewhere<br />
in the mechanism or in the pipe leading to it. I thus concluded ‘there<br />
is an obstacle’.<br />
Notice that this conclusion carries no more information than would have<br />
been given by my saying ‘there is a something, I know not what, which is<br />
such that it is reducing the water flow’ – to which, being Thomisticallyminded,<br />
I might well have added ‘et hoc dicimus impedimentum’, ‘<strong>and</strong> this we<br />
call “a blockage”’. Suppose, further, that this blockage is a small piece of<br />
masonry wedged in the inflow pipe. My earlier reasoning demonstrated the<br />
existence of this stone fragment not qua (as a) piece of masonry but simply as<br />
an existing blockage. So we might say that I proved that there is a blockage<br />
but did not show anything about its nature; after all being ‘a blockage’ is an<br />
extrinsic characterization, in this case a description of the agent from its<br />
effects (a blockage = that which blocks). In the terminology of the mediaevals,<br />
which is once again current in philosophy, I have proved the existence of the<br />
stone de re (the existence of the thing which is a stone) but not proved its