The general idea is that the god-of-the-gaps argument represents a god who resides in the ‘gaps’ of human knowledge. Because the gaps in human knowledge will almost inevitable shrink this supposedly reduces the need for God and relegates Him to lesser and lesser portion, eventually rendering God’s existence unnecessary or irrelevant.
In recent times the god-of-the-gaps argument is used most often as an objection to the arguments of natural theology advanced by philosophers and theologians who explain the gaps in scientific knowledge as specific acts of God. As such it is a variant of the argument from ignorance which is a logical informal fallacy.
Here is an example of an argument where the god-of-the-gaps objection is used to show it is informally invalid.
(1) Science has yet to explain how the biological diversity of life on earth originated.
(2) The gaps must be filled by God
(3) Therefore, the biological diversity of life on earth proves, or at least helps to show the existence of God.
Other example of arguments include the origin of the universe, the origin of life, and the fine-tuning of the conditions necessary for intelligent life. It is worth pointing out that the above argument does not represent the best of what teleology has to present.*
The idea is that placing God as the explanatory entity in the place of ignorance is an illegitimate move. Doing so either stops or hinders scientific enquiry, or leads to embarrassment when the gap is finally filled with a demonstrable or feasible naturalistic alternative.
As the argument from ignorance is an informal fallacy, there are some considerations that may render such an argument, specifically in the case of premise (2) justifiable. Let us look at some.
(1) The best explanation
The teleological argument is best understood as inference to the best explanation. This means that placing God in the gap where there is ignorance is a valid move, for it has become a probabilistic argument not looking to establish the truth of God’s existence with logical necessity. When God is posited as the best explanation, whether justified or unjustified, the detractor of the argument needs to show how God does not meet the requirements of a best explanation by (i) offering a superior naturalistic alternative or (ii) providing a plausible reason why our concept of God would not fill the gap where our supposed ignorance remains.
If one of these two requirements is not met the detractor of the design argument is merely placing something else in the gap, thus the god-of-the-gaps argument can be turned around on its head. For example, many people who use the god-of-the-gaps objection to the arguments of natural theology turn out to argue for a naturalism or scientism-in-the-gaps. I have even seen people place a provisional-agnostism-in-the-gaps! An illicit move when the argument is considering what is the best explanation, for provisional agnosticism can hardly claim to be an explanation.
(2) Distinguishing between experimental and origin science
In experimental science where things are repeatable demonstrated, placing God as an explanation to fill gaps in human knowledge is can rightly be called illegitimate. For one expects gaps in human understanding and that those gaps will eventually narrow or close with time. The idea of a gap however is that they are few and far between, or else the gaps would be described as massive plains of ignorance. Where positing God as an explanation to fill a gap where previously there was ignorance may be called legitimate is in origin science. Origin science deals with rare, often non-repeatable events and includes the study of history and forensic science. When the two branches of science are distinguished and it is obvious that researcher or investigator is operating with origin science, the gaps can assessed using Bayeseon formulae** or the criteria for the best explanation. Both methods assess the probability of given events by taking into account the relevant background knowledge, and the probability that we should have the evidence we do have given said event did not occur.
For instance, what is the probability we should have the evidence of the empty tomb, that the disciples believed they saw the resurrected Jesus, and the origin of the Christian faith such that they were willing to give their lives for their message, if God did not raise Jesus from the dead. The relevant background knowledge would be things like the expertise of Roman soldiers in execution by crucifixion, our other reasons provided by natural theology for believing that a god exists, and the cultural milieu in which Jesus’ ministry took place and the utter absence of the disciples expectation that Jesus would rise from the dead before the end of the age.
(3) Distinguishing between explanatory models
A test that determines whether the gaps in human understanding are getting bigger or smaller could be used to determine which explanatory model is superior. A careful analysis of the history of science may show that the gaps are getting smaller, so that a naturalistic explanation would be in order, or else history may show the gaps are becoming wider, so that a supernatural explanation will be in order.
Such a test may consist of the following four questions to asses the worth of different explanatory models.
1. Which model contains the fewer gaps?
2. Which model most accurately predicts where undiscovered gaps will be observed?
3. Which model most accurately forecast what scientists will discover as they use new data and technology to explore the gaps?
4. Which model is the least contrived and most straightforward in explaining both what is known and what is not yet known?
Once these criteria are assessed in light of explanatory models it could well be justified to assert that God is the better hypothesis or model. In this way, a researcher is basing the conclusion more on what is known, rather than what is unknown.
(4) Distinguishing between ignorance and impossibility
It is helpful to see the intuitive distinction between the following two statements. (i) That we can’t see how such a thing can happen naturalistically. (ii) That we can see it is impossible for such a thing to happen naturalistically. A person who utilises the god-of-the-gaps argument will often level their charge at (i) failing to see that it is (ii) that is being advocated. Thus the god-of-the-gaps argument can become a straw man argument itself.
An example of this is G. W. Lebnitz’s argument against materialism and therefore for a substance duelism. Alvin Plantinga makes the above distinction, noting that (ii) is very different sort of claim than (i).
(5) Begging the question
It begs the question to say there are no gaps at all, even if the gaps are getting smaller.
(6) Existential exclamations and the motivation for the scientific endeavour.
Advocates of the god-of-the-gaps argument often fail to understand what the theistic scientist or theologian means when they say ‘God did it.’ Most often the person is not a covering a gap of ignorance with a supernatural explanation but is expressing the wonder of God’s created order. Far from being a stopper or road-block to science it is a motivation for the theistic scientist to probe deeper into the mysteries of natural phenomenon.
The theistic worldview provides not only motivation for good science, but the necessary philosophical underpinnings for the continuance of science. For instance, on theism God has endowed humans with cognitive faculties sufficient to understand the world, whereas on naturalism there is no such confidence. Similarly, theism guarantees rationality imbues the universe so that it is possible to discover laws in nature, whereas on atheism there is no such assurance. Alvin Plantinga manages to show that on naturalism there is no way to be assured about the reality of even physical objects, let alone that naturalism is itself true, for on naturalism our cognitive faculties are selected by evolution not for truth but for survival. Thus naturalism is at root self-defeating.
(7) Distinguish between primary and secondary causation
When the theistic scientist expresses the notion that God is responsible for unexplained natural phenomena, if he is not simply expressing his awe of the created order, is rather expressing a truth lost on the advocate of the god-of-the-gaps argument. The advocate of the god-of-the-gaps argument fails to distinguish between what the theist sees as primary causation and secondary causation. God can certainly be the one sustaining concurring with natural phenomena as a primary cause, but will operate through the agency of a secondary cause, say the laws of nature.
The idea here is the theistic scientist utter a ‘Wow, this can only be achieved by a divine creator.’ Rather than this being the end of scientific inquiry, in the very next breath comes the next question, ‘How did God do this?’ Accordingly when gaps of ignorance are filled with knowledge and understanding, it does not relegate God to smaller spaces, but gives the scientist or researcher an extra reason to magnify God.
(8) Philosophical or theological expectations
A researcher or scientist may have philosophical or theological expectations of finding a gap with dimensions that make God a tidy explanation. Such as the beginning of the universe ex nihilo, or in the resurrection of Christ one expects to find a gap in scientific knowledge. In cases such as these, the god-of-the-gaps argument should be silenced, for given the philosophical or theological expectations it is wholly reasonable to posit God in the so-called gap. Two examples follow.
First, early last century science suddenly struck upon empirical evidence for the beginning of the universe out of nothing, against the expectaions of the current cosmogony, namely the Steady State Theory. How the universe literally came into being is widely recognised to be a matter beyond science, for in the singularity, all material things, including time itself, began to exist. As science seeks to provide answers to all naturally occurring phenomenon the ultimate first cause of the origin of the universe will fall outside of the scientific endeavour. The formulation of Big Bang Cosmology creates a big “gap” for science, but a gap such as this has quite easily been filled by philosophers and theologians who expected it, for the cause of such an event can only be immaterial and timeless therefore changeless, uncaused and beginningless, enormously powerful and therefore a personal creator.
Second, The initial boundary conditions of the universe are themselves beyond the scope of science, and so one would expect explanations for these to also be outside science.
This does not mean, in and of itself, that these expectations are not subject to naturalistic defeaters. But even if these laws or discoveries are not beyond science, based on current expectations of philosophy and theology, and in the absence of naturalistic defeaters one can be justified when positing God to fill such a gap.
(9) Auxiliary reasons
Similarly we can have auxiliary reasons to think that God fills the gap, for instance in the biblical texts, or other special revelation. Alvin Plantinga suggests it may be that such beliefs are basic, and result from when human cognitive faculties are functioning correctly in the appropriate environment.
(10) Religiously neutral premises
In religiously neutral premises the god-of-the-gaps argument can find no foothold.
For instance, the second premise in the Kalam cosmological argument that the universe began to exist, can be found in almost any science text book. The first premise, that whatever begins to exist has a cause, is also religiously neutral as it does not take belief in God but only common sense to agree with it. Although the conclusion that therefore, the universe has a cause cannot be said to be religiously neutral, the charge of placing God in the gaps cannot therefore be levelled against the argument.
Another example, the premise the result of the appearance of design is either due not physical necessity, chance or design, carries with it no religious baggage. Plus it is entirely plausible as it seems to exhaust all the possibilities for the appearance of design.
(11) The inference to design
The inference to design may come after sufficiently demonstrating that the appearance of design is not due to physical necessity or by chance. William Dembski has advanced a sophisticated and highly nuanced method for a design inference that does this. The inference to design hinges around the idea of ‘specified complexity,’ where the given probability is not only vanishingly small but also conforms to an independently given pattern.
(12) Design detection
According to Intelligent Design theorist one can discover the products of design without having any idea as to how those products came about. The practitioner of theistic science is therefore not committed either way to the gaps of history of the cosmos or understanding in human knowledge. The god-of-the-gaps objection usually fails to take this into account.
The motivations of the advocates of design arguments are absolutely irrelevant to the truth or falsehood of the premise or the conclusion that follows. To claim the argument is unsound because of the religious or apologetic motivations is the genetic fallacy.
* Here is a better representative of the teleological argument.
(1′) The fine-tuning of the universe is due to either physical necessity, chance, or design.
(2′) It is not due to physical necessity or chance.
(3) Therefore, it is due to design.