Re: Of Martian Sculptures (was: Re: [asa] on science and meta-science)

From: Iain Strachan <>
Date: Thu Nov 12 2009 - 17:49:39 EST

On Thu, Nov 12, 2009 at 8:49 PM, Cameron Wybrow <> wrote:
> David:

> But the same objections apply in the case of the travel-worn space probe. We
> have no independent knowledge -- knowledge other than the existence of the
> probe itself -- that any other intelligent life exists in the universe, so
> objection (a) above applies.  And we have no independent knowledge --
>  knowledge other than what can be inferred from the probe itself -- of the
> nature, habits, motivations, inclinations, etc. of the purported designers,
> so objection (b) applies.
> In the case of the space probe, our inferences, both of the existence and of
> the character of the purported designers, depend *entirely* upon what we can
> discover from the probe itself.  We have no warrant for inferring anything
> else about the designers.  Our certainty that such designers exist, that
> they have certain capacities, etc., springs from a *design inference* that
> *rests entirely upon the very thing whose design status is being debated*.
> So, when the question is asked:  "Is this metallic object from outer space
> designed, or only the product of chance and natural laws?", our design
> inference is made in violation of objections (a) and (b) above.  Yet we
> would feel certain that our design inference was valid, and rightly so.  Our
> own practice would show that we do not consider the criteria used to reject
> design inferences (given above) to be sufficient criteria for such
> rejection.
> It follows that the TEs on this list should abandon the above-described
> *general* argument which rules out design inferences from natural objects to
> a designer of natural objects.  There remain available to TEs, of course,
> *particular* objections that *particular* inferences from nature to a
> designer of nature are invalid, or are made on evidence that is too skimpy,
> and so on.  I carry no brief against such *particular* objections.  It is
> the general objection that I reject.  In practice, the real-life behaviour
> of everyone on this list negates the objection, which shows that it is not a
> principled objection, but an intellectual *deus ex machina* called up to rid
> TEs of the hard work of having to deal with particular design inferences,
> one by one.

Sorry, but I'm not convinced. I think you do have independent
knowledge of the likely nature and inclinations of the designer of the
spacecraft. That independent knowledge is the existence of us; for we
design and build space-ships with much the same likely intent as the
designers of the alien space-ship - namely presumably for the
exploration of space.

Consider my building example. You say that you know about the
existence of the Architect (a) for Building A. Building B has similar
properties to building A (doors, rooms, windows etc), so you infer
that it also was designed by an Architect (b). You don't know _which_
Architect, but it is reasonable to assume that it was an Architect
with similar intentions to the designer of building A.

Likewise the alien space probe. You know that a human space probe was
designed by an intelligent life form (a) [ a human life form]. If you
believe life arose naturally on earth, it is reasonable to assume that
it could arise naturally on another planet, and that therefore the
alien probe was designed by an alien life-form (b). You can even
estimate the probability of life arising on another planet.

The problem with just postulating an unspecified "Designer" is that
you can't estimate the probability of the existence of such a thing.
With the alien space probe you can estimate the probability (even if
it is a rough thing like the Drake equation).

Fundamentally, my version of the "independent evidence" objection lies
in Bayesian statistics. One makes an inference based on a prior
probability (of existence of said designer), modified to a posterior
probability, based on the evidence (existence of the watch, statue,
space probe), to a posterior probability.

But any such calculation breaks down and is literally nonsensical if
you can't estimate a prior probability. You can't estimate a prior
probability of God existing in any realistic way. It comes down to
your philosophical belief. An atheist will simply make the prior
probability so low that the posterior is also incredibly low.

I had two colleagues that were arguing about the probability of God
existing. One said 10^(-100) and the other said zero. The 10^(-100)
fellow said of the zero fellow; "Now that's what I call faith!"


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Received on Thu Nov 12 17:50:03 2009

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