The God of the gaps refers to a view of God deriving from a theistic position in which anything that can be explained by human knowledge is not in the domain of God, so the role of God is therefore confined to the 'gaps' in scientific explanations of nature. The concept involves an interaction of religious explanations of nature with those derived from science (see also Relationship between religion and science). Within the traditional theistic view of God as existing in a realm "beyond nature", as science progresses to explain more and more, the perceived scope of the role of God tends to shrink as a result.
"God of the gaps" is often used to describe the perceived retreat of religion in the face of increasingly comprehensive scientific explanations of natural phenomena. An example of the line of reasoning starts with the position that early religious descriptions of objects and events (such as the Sun, Moon, and stars; thunder and lightning) placed these in the realm of things created or controlled by a god or gods. As science found explanations for observations in the realms of astronomy, meteorology, geology, cosmology and biology, the 'need' for a god to explain phenomena was progressively reduced, occupying smaller and smaller 'gaps' in knowledge. This line of reasoning commonly holds that since the domain of natural phenomena previously explained by God is shrinking, theistic or divine explanations for any natural phenomenon become less plausible.
One modern example of God in the gaps is the theory of the origin of life. There are many ideas that different experts believe, yet no one idea holds the confidence of most of these experts. This uncertainty allows one to more reasonably maintain a God of the gaps viewpoint.
The term goes back to Henry Drummond, a 19th century evangelical lecturer, from his Lowell Lectures on the Ascent of Man. He chastises those Christians who point to the things that science can not yet explain — "gaps which they will fill up with God" — and urges them to embrace all nature as God's, as the work of "... an immanent God, which is the God of Evolution, is infinitely grander than the occasional wonder-worker, who is the God of an old theology."
In the 20th century the term was used by Dietrich Bonhoeffer in letters he wrote while in a Nazi prison during World War II, which were not made public until years later. The term gained attention in 1955 when it was used in the book Science and Christian Belief by Charles Alfred Coulson, where Coulson states: "There is no 'God of the gaps' to take over at those strategic places where science fails; and the reason is that gaps of this sort have the unpreventable habit of shrinking."
After simmering in theological and philosophical circles, the term gained yet wider attention from a 1971 book and a 1978 article, both by Richard Bube. He articulated the concept in far greater detail, most notably in Man Come Of Age: Bonhoeffer’s Response To The God-Of-The-Gaps (1971). Bube attributed modern crises in religious faith in part to the inexorable shrinking of the God-of-the-gaps as scientific knowledge progressed. As humans progressively increased their understanding of nature, the previous "realm" of God seemed to many persons and religions to be getting smaller and smaller by comparison. Bube maintained that Darwin's Origin of Species was the "death knell" of the God-of-the-gaps. Very importantly, Bube also maintained that the God-of-the-gaps was not the same as the God of the Bible (that is, he was not making an argument against God per se, but rather asserting there was a fundamental problem with the perception of God as filling in the gaps of knowledge).
Since the 1970s, the term has increasingly been used by philosophers and theologians in reference to the problem of making the assumption that the currently unknown is necessarily where God "resides."
The term God-of-the-gaps argument usually refers to an argument that assumes an act of God as the explanation for an unknown phenomenon, and is a variant of an argument from ignorance. Commonly such an argument can be reduced to the following form:
One example of such an argument might be as follows: "Because science can't figure out exactly how apples fall, it must be God who causes it to happen."
The God-of-the-gaps argument is the target of frequent criticism, often over the fact that the so-called "explanation" it provides for unexplained phenomena is not really an explanation, but rather an argument from ignorance. Such criticism is usually related to the use of the God-of-the-gaps-argument as proof of the existence of God. A common argument is that the lack of scientific knowledge about an unexplained phenomenon does not mean that it is an act of God, but rather that scientific research has not yet found an answer.