FOM: Existential commitments, knowledge and "God" - reply to Shipman

[Ketland,JJ]

Joe Shipman asked me how I know that God doesn't exist. This is way
off-topic (for fom), but I hope the moderator will forgive us a bit of
philosophy (especially as Shipman argues that this topic has foundational
import).

Shipman's question is epistemological. How do I *know* that God doesn't
exist? Equivalently, how do I *know* that "God" designates nothing?
Actually, I didn't say "I know that God doesn't exist". I just said "God
doesn't exist". Raymond Smullyan is rather good on the difference between "I
know/believe that p" and "p". (See R. Smullyan "An Epistemological
Nightmare", Chapter 25 in "The Mind's I", 1981, edited by D. Hofstadter and
Dan Dennett, Basic Books). I'll discuss the epistemological issue below.

My views about the epistemology of existence as well as the logic of
existence are pretty Quinian, for good or ill. That means "exists" is always
to be understood as a quantifier, vacuous names are to be parsed away using
descriptions (i.e., replace sentences containing the term "God" by sentences
containing the predicate "x is a god"). Like Kant and Frege I think that the
ontological argument (God is perfect; existence is a property; if God did
not have the property of existence, He would not be perfect; so He exists)
is invalid, because existence is not a predicate (as Kant put it). You
cannot deduce existence from essence (i.e., from a definition). (Of course,
logicians are free to pursue ontological first-philosophy if they wish).
Finally, existential commitments can be read off theories in the way Quine
suggested: examine what the quantifiers must range over if the theory is to
be true. This is how we see that modern theoretical science carries a
tremendously rich ontology, including a vast mathematical ontology,
including infinite sets (e.g., of spacetime points: a co-ordinate chart is
an infinite set; a tensor field is an infinite set).

As for the *epistemology* of what exists, I admit: it's really just a guess
or a conjecture on my part that God doesn't exist. (I agree with Hume and
Popper here: we don't really *know* anything: we just have more or less
rational guesses. Even the consistency of PA is just a guess, although
presumably an extremely rationally acceptable one). But I think the
non-existence of God is an extremely rational guess to adopt, given modern
science.

That is, given the gradual overthrow, from Galileo through Darwin to
Dawkins, of non-predictive religious superstitition by serious explanatory
and predictive scientific theory, and given that God has no place (except a
metaphorical place: c.f., Hawking's Mind of God, Einstein's non-dice-playing
God) in the serious, properly empirically-accredited, explanations of
science, I read my existential commitments from successful science. Protons
and genes are in and God is out. (In fact, I think that infinite sets are in
also, because they are indispensable to empirical science). There are, to be
fair, some recent cosmological and design arguments for the existence of God
(to do with the precise values of the basic physical constants being just
right to produce life, to do with the incredibly unlikely low-entropy of the
Big Bang, etc.) but I'm not convinced.

Perhaps the best argument against the existence of a benevolent omnipotent
creator is the existence of pointless human suffering. Voltaire was rather
good on this point. God, being omnipotent, could easily have prevented The
Third Reich, Apartheid, Rwanda and so on. Being benevolent, he *should* have
done so. But He didn't. If there is an omnipotent creator, I suspect that He
is rather callous.

Final word: Shipman writes that "(a justification for passing from a
Universal to
an Existential can be made in certain contexts on the ground that many
sorts of existence [e.g. existence of infinite sets] are instantiated in
the Mind of God)."

My reply: infinite sets can look after themselves. I hate to sound
excessively positivist, but being "instantiated in the Mind of God" means
nothing to me, except as a kind of Berkeleyan-sounding metaphor (Berkeley
famously held that the external world is immaterial, made of ideas, which we
perceive: esse est percipi. He explained how chairs and tables continue to
exist when *not* perceived by us, by saying that they are still perceived by
the Mind of God). If God just spent a bit more time thinking about the
important things, like human pain and suffering, rather than infinite sets,
the world might be a nicer place! 


Jeff Ketland

Dept of Philosophy, LSE