I have been pondering about this, and I can't find a definitive, easy
answer. I was wondering if I could get some ideas here.

  Skepticism is often defined as "not accepting claims at face value,
without proper evidence". However, what makes evidence "proper" and
"valid"? The answer to that question isn't as easy as one might hastily
think.

  One could argue that valid, proper evidence must be testable and
verifiable. While that's certainly a necessary property of such evidence,
it isn't sufficient.

  For instance, an apologetic could argue that the existence of life is
evidence for the existence of a god, and the existence of life is certainly
testable and verifiable. However, the mere existence of life, while
verifiable, isn't sufficient evidence for the existence of any god, hence
this purported evidence is not proper. But what makes it not proper?

  One could say that one reason why it's not proper is because there's a
deductive fallacy being committed here, like:

  1) God is an explanation for the existence of life.
  2) Life certainly exists.
  3) Therefore God exists.

  This is the "affirming the consequent" fallacy. (The first proposition
can be formulated as "if God exists, he created life".)

  An even clearer case of "affirming the consequent" is that the alleged
existence of supernatural miracles is given as evidence for the existence
of a god. (You see this *all the time*. People will argue how miracle
healings happen all the time, how people speak on tongues and whatever.
And this is somehow evidence for the existence of God.) Here the fallacy
goes like:

  1) If the God of the Bible exists, he performs miracles.
  2) Miracles do happen.
  3) Therefore the God of the Bible exists.

  (Even if we accepted the first two premises, the conclusion is incorrect.
This is no different from "if it rains, I get wet; I'm wet; therefore it's
raining".)

  In these examples the existence of life and the alleged existence of
miracles (even if we granted that assumption) are not valid evidence for
the existence of a god. That's just a deductive fallacy.

  However, let's compare it to something that *is* considered valid and
proper evidence for something else, namely the theory of evolution:

  Evolutionary biologists predicted the existence of fossils of a flat-headed
fish with eyes on top somewhere in late devonian strata before they were
found. Motivated by this prediction they searched for such fossils in
geological strata of that age, and they found exactly that. (It was later
named "tiktaalik".) This was a marvelous prediction of the theory of
evolution, and a wonderful piece of evidence for its validity. Nobody
doubts this is valid and proper evidence.

  However, an apologist could argue that the same deductive fallacy is
being committed here, namely:

  1) If the theory of evolution is true, then we should find fossils of
a flat-headed fish with eyes on top somewhere in late devonian strata.
  2) Such fossils have been found in the correct strata.
  3) Therefore the theory of evolution is true.

  But this is the exact same "affirming the consequent" fallacy as before!

  What makes the difference? Why is this evidence for evolution valid and
proper, but eg. the existence of life or alleged miracles for the existence
of a god isn't?

-- 
                                                          - Warp

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