Imagine you and I are walking down an alley, and we see a man who has been
stabbed to death. I might propose that there must have been an
assailant. You might propose there must have been two; you might make an argument from the proof presented, maybe he appears to have been a strong man with a powerful frame who could have fought off a single attacker of typical size, maybe there are signs of a larger struggle, extra sets of
footprints. But suppose you insist that there must have been
three assailants? Or ten, or twenty? Each assailant is an additional
assumption, and each one added reduces the
probability of that number actually being
necessary to explain the assault. And what happens if you propose an
infinite number of assailants?
The probability effectively drops to zero.
And for good measure, we are forced to consider that an infinite number of assailants would take up infinite space, and would require infinite time to complete their assault, such that we ought not find a lone dead body at all, but a perpetually ongoing assault. And even more perplexing, even if we witnessed an ongoing assault, wherein our victim was stabbed by one assailant after another after another after another after another after another, we could never know that the assault was indeed infinite, for it might end a minute after we leave the scene (or, if we never leave the scene, a minute after the last of us dies of extreme
old age). There is not enough time in our lives to observe, nor capacity in our minds to process all of the available
evidence to conclude anything more than a very, very large number. And even very, very large numbers are vanishingly small as compared to any arbitrary numbers of a few magnitudes more.
Ultimately, the infinate assailant problem illustrates the difficulties encountered in proposing infinite causes as explanations for finite circumstances. Where the circumstance is one for which a finite cause could account, even finite multiples of that cause become increasingly improbable, while finite multiples which are massive from our perspective, but miniscule from arbitrarily larger perspectives, can already come to exceed the power of observation and understanding delicately ensconsed in the human
brain.