A question asked by some philosophers concerns how the soul interacts with the body. The allusion by skeptics is that since we do not know how the soul moves the mind and body, why then it must not be able to. Such an argument is an ironic twist of the God-of-the-gaps fallacy, a type of atheist-of-the-gaps fallacy. We cannot explain it, so it must not be true.
The alternative to the existence of a soul is pure physical naturalism, the position that all that exists is chemistry and physics and their emergent properties. We cannot see, smell, hear, or touch electromagnetism, but we can measure it and demonstrate that it is a property of natural forces.
I once had an atheist ask me “what instrument can I use to measure the soul?” The clear implication is that if I cannot measure it, it must not exist. My response is to point out the myriad of things that we cannot measure with instruments, but we nevertheless hold to exist. For my atheist friend to be consistent, he would have to conclude that the list of things that do not exist because we cannot measure them would include justice, irony, humor, love, beauty, Lady Macbeth’s emotions, and a host of other things that make life worth living.
The king of the skeptics, the philosopher David Hume, was known for his rigor in holding to his skepticism, tried to deal with this exact issue. In his book An Enquiry Concerning Human Understanding, he claimed that
That the square of the hypotenuse is equal to the squares of the other two sides, cannot be known, let the terms be ever so exactly defined, without a train of reasoning and enquiry. But to convince us of this proposition, that where there is no property, there can be no injustice, it is only necessary to define the terms, and explain injustice to be a violation of property. This proposition is, indeed, nothing but a more imperfect definition. It is the same case with all those pretended syllogistical reasonings, which may be found in every other branch of learning, except the sciences of quantity and number; and these may safely, I think, be pronounced the only proper objects of knowledge and demonstration.
So Hume concludes that “the science of quantity and number” are “the only proper objects of knowledge.” The problem, of course, is that this statement by Hume, and indeed his entire collection of writings, are neither quantity nor number, so by his own standard we can dismiss his writings as not proper knowledge. Hume is, at bottom, self refuting. Even he seems to admit so, when he once stated “When we leave our closet, and engage in the common affairs of life, its conclusions seem to vanish, like the phantoms of the night on the appearance of the morning; and it is difficult for us to retain even that conviction, which we had attained with difficulty.” In other words, we ultimately have to put our little game back in the closet and return to regular life, where we know we cannot doubt such things.
So the skeptics system is built upon a premise that God does not exist and only physical things are worth knowing, then tries to convince us through argument that arguments are futile. He tells us that “only things that we can measure with instruments are worth knowing” but this statement itself cannot be measured with instruments.
I would much prefer the Biblical book of Romans with its iron logic, or the Psalms with their beauty.