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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Further Reflections on <strong>Atheism</strong> 203<br />
This is a clever argument. The supposition that God is maximally great<br />
implies that God exists in all possible worlds. If so, he exists in that possible<br />
world which is the actual world. But what about the premise that if God is<br />
maximally great, he exists in all possible worlds? Unlike Plantinga I follow<br />
Quine in parsing proper names as predicates so that for example ‘Socrates’<br />
becomes ‘the x such that x socratises’ which denotes nothing if there is no<br />
socratiser. (You can think of the predicate ‘Socrates’ as (say) ‘has a snub nose<br />
<strong>and</strong> fought in war <strong>and</strong> taught the author of the Republic’ or things of this<br />
sort.) Unlike Kripke <strong>and</strong> Plantinga I don’t treat proper names as so-called<br />
‘rigid designators’, but not much turns on this for the present argument.<br />
However, it is not clear that anything is maximally great in my world, since<br />
it is logically possible that in all worlds any degree of greatness could be<br />
exceeded by a greater. That is, one might be sceptical about the premise that<br />
a maximally great being is possible.<br />
At the propositional level it is provable in C.I. Lewis’s system S5 (see<br />
Prior, Formal Logic 7 ) that if it is necessarily the case that if possibly p then p,<br />
then it is the case that if possibly p it is the case that if possibly p then<br />
necessarily p. We cannot deduce the consequent of the main hypothetical<br />
from its antecedent in the general case because we do not have ‘if possibly p<br />
then p’ but Plantinga’s moves with possible worlds suggests that in the special<br />
case of ‘a maximally great being exists’ we may say ‘if possibly p then p’.<br />
Equally, however, as Plantinga concedes, there could be a counterargument.<br />
It seems possible that in no possible world is there a maximally<br />
great being because however near to maximality a being is, there is another<br />
possible world which has a still greater greatness.<br />
Let us look at the matter more simply <strong>and</strong> omitting steps. Let p abbreviate<br />
‘a maximally excellent being exists’. Plantinga has argued in effect for the<br />
soundness of the deduction from ‘possibly there is a maximally excellent<br />
being’ to ‘a maximally excellent being exists’, i.e. in the notation of propositional<br />
logic from ‘Mp’ to ‘p’, where ‘M’ abbreviates ‘possibly’ <strong>and</strong> ‘p’ abbreviates ‘a<br />
maximally excellent being exists’. This is of course not a valid deduction in<br />
pure propositional logic because Plantinga has gone through quantified modal<br />
logic <strong>and</strong> also has used some definitional statements about maximality <strong>and</strong><br />
excellence. These could be queried <strong>and</strong> an argument could equally be constructed<br />
from the atheist ‘not p’ to ‘not possibly p’. I have my Quinean doubts<br />
about quantified modal logic cum possible world semantics. But allowing the<br />
logic, the atheist could question one or other of Plantinga’s assumptions. We<br />
might question whether a maximally excellent being is possible. For any<br />
degree of excellence there might always be a greater one.<br />
My conclusion is that Plantinga’s argument is of considerable subtlety<br />
(<strong>and</strong> I have skated over some moves that he makes explicitly) but I conclude<br />
that it cannot be used by the theist to convince an atheist (the Fool as<br />
Anselm calls him).