During Greg Koukl’s August 10th radio broadcast, he shared some thoughts about the criterion of falsifiability as it relates to theism, that I found worth passing on (with some expansion and commentary of my own).

Some claim theistic belief is not reasonable, because theism cannot be falsified.  For something to be falsifiable requires that there be an imagined set of circumstances that would demonstrate a particular view to be false.  For example, Christianity would be falsified if archaeologists ever unearthed Jesus’ body from a grave outside Jerusalem.  The idea behind the principle of falsifiability is that if, in principle, there can be no evidence that counts against a view, then it is not possible to have a reasonable conversation about the merits of the view.

While this is a useful principle, clearly it is not an absolute criterion for a theory/belief to be reasonable, nor is it necessary to have a reasonable conversation about its merits.  For example, consider the belief that you exist.  Can you imagine any set of circumstances that could convince you that you do not exist?  No.  It is inconceivable.  And yet we are fully reasonable in our belief that we exist.

While falsifiability is a useful way to evaluate a theory/belief, the merits of that theory/belief do not hang on its falsifiability.  Its merits hang on the evidence in its favor.  Theism has several lines of evidence in its favor.  That body of evidence serves as the basis for a reasonable dialogue concerning the veridicality of theism.

More to the heart of the matter, falsifiability cannot be an appropriate test for theism because it is impossible to falsify a universal negative.  And in order to falsify God’s existence, one would have to prove a universal negative: God does not exist.

To be fair, I should qualify my statement that a universal negative cannot be proven.  While a universal negative cannot be proven empirically, it can be proven logically.  If something is logically contradictory, or incoherent, we can be sure it does not exist.  For example, I can prove there are no square circles.  I cannot, and need not do so empirically, but I can do so logically.  The concept of a square circle is incoherent, and thus square circles cannot exist.  Some atheists contend that theism is logically incoherent, but few have been persuaded of their arguments.  In the past, the most common attempt to show theism was incoherent was the problem of evil.  It was reasoned that if God is all good and all powerful as theism claims, evil should not exist.  And yet it does, hence, theism must be false.  Philosophers have since come to realize that the existence of evil is logically compatible with the existence of an all-powerful and all-loving God.  It stands, then, that the very nature of theism is that it cannot be falsified, and thus this should not count against the view.  The focus should be on the evidence for theism, not its unfalsifiability.