Theoretically, non-naturalist arguments might be thought come in two main
types: Those depending on positive evidence and those depending on
conclusively invalidating naturalism.
But, in practice, nearly all non-naturalistic arguments are arguments that
attempt to use the latter method or that simply commit the fallacy of
arguing from ignorance. This is because they assert that naturalist theory
is impossible merely because the non-naturalists don't have knowledge of an
acceptable (to them) naturalistic theory, or they misrepresent naturalism in
order to impute flaws to it that it doesn't have, thus effectively arguing
from their ignorance of naturalism and its actual implications.
Because attempts to directly refute naturalism as such have been such
failures, non-naturalist often attempt to refute it through refuting
particular naturalistic scientific theories, such as the naturalistic
theories of evolution. Non-naturalists do this by attempting (usually
unsuccessfully) to show that there is some flaw in the theory and then
triumphantly -- but prematurely -- proclaiming the victory of their pet
variant of non-naturalism.
What non-naturalists forget or fail to learn is that it is not enough to
invalidate a particular naturalistic theory. They must also prove that no
true naturalist theory is even possible. If they don't do this, they have
not proved non-naturalism, because the burden of proof of non-naturalism
goes beyond that of naturalism. So, even without any current specific
explanation for something, naturalism must still be assumed, unless one
simply chooses to be arbitrary, to step outside the realm of rational
argument.
Only in the case were naturalism as such can be shown to be contradictory or
to imply a contradiction does non-naturalism get support. It appears that
this does not happen very often.
Is this asymmetry fair to non-naturalism? Shouldn't non-naturalism and
naturalism both get the same treatment? They would get the same treatment
were it not that non-naturalism accepts the existence of a natural world
(which is were naturalism stops) and then asserts the existence of something
beyond the natural world. Since naturalism does not do this, it has no
burden of proof in this respect. Since non-naturalism does do this, it does
have the burden of proof in this respect.
The extra burden of proof is its own damn fault. If non-naturalists seek to
reduce the burden of proof, they must reduce their claims. When they shrink
their theory to the size of naturalism, they will no longer have a special
burden of proof - and, of course, they will no longer have non-naturalism -
but that's a small price to pay for eliminating the so-far-uncarried burden
of proof of non-naturalism. There is no logically possible way to make
non-naturalism equal to naturalism in this respect except to give up the
portion of it that goes beyond naturalism.
Non-naturalists cannot even usefully invert the metaphysical status of the
real world. That is, it doesn't help to argue that only the non-natural
world is really real and that the real world is really a kind of
hallucination.
Why? Because, like it or not, whether real or not, our world is our
epistemologically real world, our epistemological base world, our
perceptually axiomatic world, our cognitively objective world.
Also, of course, this non-naturalist ploy is circular. It assumes the
conclusion and then uses that assumption to attack the acceptance of the
cognitively objective world.
The purely philosophical approach is essentially the same. Some fact or set
of facts is alleged to be naturalistically impossible. This means that the
only alternative is some form of non-naturalism. Sometimes, again, the
appeal is directly to ignorance (or as nearly so as the non-naturalist feels
he can get away with) or to claimed contradictions that, upon examination,
either dry up, or are seen to rest on unproven non-naturalist assumptions,
or, in those rare occasions where the naturalistic theory really is flawed
in some way, on the often-unspoken and unacknowledged premise that, if that
one naturalistic theory is false, then, obviously, no naturalistic theory
can possibly be true.
Sometimes, also, the alleged fact is simply not a fact at all, or is not
known to be a fact. For example, not only is it circular to assume the
non-natural status of the mind and then use it as evidence of
non-naturalism, it is not known to be a fact that the mind is non-natural.
Nor is it possible to use the alleged fact of the non-occurrence of
macroevolution in life on Earth as a justification for non-naturalism,
because it is not known that macroevolution does not occur (again, we see
the asymmetry that the non-naturalist takes on by virtue of adopting
non-naturalism instead of the less-ambitious naturalistic approach - the
failure of macroevolution to be a fact would not hurt naturalism or help
non-naturalism).
Since naturalism, as a metaphysical claim, is simply the assumption that the
natural world is natural, it is not easy to attack it on its own terms. It
is too simple, too elegant, and way too minimalist. It's what's left if you
remove every trace of naturalism from your view of the world. There cannot
logically be a simpler theory of the nature of the world that can work,
because, to remove any aspect of this basic premise is to deny one's own
existence and thus to remove oneself from the logical right to participate
in the discussion at all until that question is resolved.