"God of the gaps" is a general name for any theological argument that argues for the necessary existence of God as an explanation for some particular phenomenon that challenges the limits of human understanding. In modern times, it has the distinction of being an approach to apologetics more favored by atheists than theists.
An early critic of this form of argument was Henry Drummond, a Christian evangelist and science enthusiast, who objected to it primarily on the grounds that it reduced the all-encompassing glory and power of God, a glory and power capable of encompassing the entire universe, to something large enough only to fit a given hole in our understanding of that universe. Later, the well-known Christian theologian and anti-Nazi activist Dietrich Bonhoeffer added to this critique the observation that the ongoing advance of scientific knowledge was making those "gaps" smaller and smaller, and thus less and less able to hold any reasonable conception of God.
At the same time as such arguments were being increasingly discredited by theologians and believers, they were simultaneously gaining popularity among atheists as being usefully easy to debunk. In the present day, they are particularly favored, for example, by the biological theorist and atheistic polemicist Richard Dawkins. A typical Dawkinsian "God of the gaps" argument begins from the assumption that best argument in favor in belief in God is that only God could have produced the wealth of diversity we see in living creatures, proceeds to demonstrate that science has crafted a plausible, well-supported, naturalistic explanation for the same, and concludes that belief in God is therefore rendered wholly superfluous and unnecessary.
Given how thoroughly "God of the gaps" has been discredited by the best minds on both sides of the debate, it may seem a fool's errand to seek anything worth salvaging within it, and yet I have recently become convinced that there is a core insight hidden in this argument, unappreciated by any of its modern critics. To uncover it, let us start by unpacking the central metaphor. We can picture human knowledge as being solid ground, and the "gaps" in that knowledge as being holes in the ground. Originally, so the story goes, these gaps were huge gaping chasms, and it was easy to imagine God living somewhere down inside them, but now they have shrunk to the size of little ditches, and we can all see for ourselves that there is nothing inside.
Yet, if we wish to be fair to all those medieval theologians, we must acknowledge that it was not actually all these little gaps as we know them today they were contemplating. It was the big gap, the one at the outermost edge of human knowledge. After all, if knowledge is a land mass, it must be an island, it does not extend forever, it has an outside boundary somewhere. At one time, when you contemplated questions like the origin of the species or the motion of the planets, you were traveling to the very edge of human understanding and looking out into the vastness beyond. The fact that such questions seem diminished as mysteries of existence is not just because we are filling in the gaps, but because we have built outwards past the old edges, so that the view out towards the horizon is no longer unobstructed.
Thus, the question becomes: In what kind of knowledge landscape do we find ourselves? Are there an infinite number of mysteries in the universe? Are the limits of possible understanding located an infinite distance away? If so, no matter how far out we extend our framework of knowledge, there will always be an outer perimeter, outside which will remain an space so infinitely big that it might arguably serve well as a divine domicile. Conversely, do we, as the "God of the gaps" criticism implies, live in a bounded knowledge space, a room, so to speak, of large but finite size, containing a countable finitude of things to learn, a space in which even now we have drawn near to its firm boundaries, and in which we merely need to fill in the few small holes that remain? The second option might, in fact, be true, but to assume it given our current state of knowledge requires, in my opinion, a considerable act of faith.
Of course, any metaphor that envisions the limits of knowledge as a fully enclosed space inevitably calls to mind the famous Allegory of the Cave from Plato's Republic. In this extended metaphor, Plato describes the ordinary world as we experience it as no more real than shadows cast upon the wall of an underground cave. No amount of examination of the subterranean world itself brings you any closer to what Plato considers the truly important truths of life. Instead, to gain real wisdom, you must ascend to the surface, where you can finally gaze out across the void of the heavens and perceive the sun, the source of all heat and life (an entity identified by Plato's disciples, the Neoplatonists, as a metaphor for God). Thus, in Plato's view, we perceive God not in the fulfillment of the promises of our ordinary knowledge, but in its absence. We draw closer to God not by extending what we experience as knowledge outward, but by leaving it behind.
Chris Sunami writes the blog “The Pop Culture Philosopher,” and is the author of several books, including the social-justice oriented Christian devotional Hero For Christ. He is married to artist April Sunami, and lives in Columbus, Ohio.