The presumption of atheism is the idea that in debates between theists and atheists, the burden of proof is on the theist to prove that God exists. This principle appears to be taken for granted in popular atheist literature, but I seldom see it discussed in higher level philosophy of religion. Is the validity of the presumption of atheism widely accepted among professional philosophers?

(Of course, accepting the presumption of atheism does not entail accepting atheism itself. One can accept that the theist has the burden of proof, but believe that the burden has been met.)

  • 1
    Presumption of atheism? Atheists also have a burden of proof that god does not exist. Without that they can't convince believers (not saying theists, theism supposes some religion, and people can be convinced there) in atheism.
    – rus9384
    Commented May 23, 2018 at 23:35
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    This is a standard application of the rules concerning the burden of proof, the burden is on the one making the claim. That God is for theists and that God is not for atheists, the only position without the burden is the agnostic one.
    – Conifold
    Commented May 23, 2018 at 23:35
  • You may find Antony Flew's article "The Presumption of Atheism" of interest. I myself disagree with Flew and share the sentiments of rus9384 and Conifold. Commented May 24, 2018 at 0:27
  • Why only theists? What about Monists? There are many discussions over the centuries in the Indian (Advaita and Buddhist) texts on this. Their conclusions are that God cannot be proved in the empirical or sensual universe. The 'proof' of God (i.e., an absolute being) is beyond the senses. Commented May 24, 2018 at 5:12
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    Atheism is nothing more than a lack of belief in deity. It may be useful for you to distinguish the term from the person(s) identified or identifying as atheist, as well as distinguishing the concept from arguments claiming positive or negative ontological status.
    – MmmHmm
    Commented May 25, 2018 at 11:02

5 Answers 5


There is an alternative to "proving" either proposition: recognize that the propositions themselves are beliefs (i.e., unprovable, subject to personal boundaries), not facts (i.e., provable, not subject to personal boundaries).

The so-called "presumption of atheism" is invalid. In fact, isn't it based upon the fallacy of begging the question?

The fallacy of begging the question occurs when an argument's premises assume the truth of the conclusion, instead of supporting it. In other words, you assume without proof the stand/position, or a significant part of the stand, that is in question.


Rather than debate who's responsible for proving the unprovable, both the theist and the atheist are each responsible for holding only themselves to their own beliefs.


Any discussion of God is trivial if it doesn't identify which God is being discussed.

How can an atheist prove the non-existence of an unidentified God?

A monotheist, if they wish to reverse the burden of proof, must first be able prove the non-existence of every God which is other to the God they presume.

  • Counter-example to your first sentence: "deity is an abstract idea, and like all abstract ideas, deity does not exist; it is only to be found in language." No identifying of specific deities required to make a non-trivial point and discuss. That said, of course - what ever in the world do you (or does anyone) mean by your use of the term "God"? There is only axiomatization or personal opinion, no empirical verification by which to rationally assess a truth value to statements and propositions regarding such.
    – MmmHmm
    Commented May 25, 2018 at 11:19
  • "How can an atheist prove the non-existence of an unidentified God?". Atheism is not about proving the unexistence of deities; atheism simply says "I do not find your proof of the existence of deities convincing". An undefined/vaguely defined deity is a lot easier to say that to.
    – MichaelK
    Commented Jun 4, 2018 at 12:05
  • @Mr.Kennedy I think those issues could be resolved by user33399 quoting "God" to identify when he is using it as a word or abstract idea, and perhaps use the word "entity" in places where he is referring to a single entity that an indivudual believes in.
    – Cort Ammon
    Commented Dec 12, 2018 at 15:36

I think what you call the "presumption of atheism" is just a specific instance of Occam's Razor, which translates as "Don't complicate things unnecessarily." In other words: don't assume the existence of anything that does could possibly not exist.

Also, definitions of God are often so vague that proving God doesn't exist runs into a perpetual game of moving goalposts. "Sure, you proved that God, by that definition, does not exist, but what if you define God as..." Asking the theists to prove God exists also allows them to firmly establish a set of goalposts.

  • You have misrepresented Occam's Razor here. Occam's Razor states: "do not multiply entities beyond necessity". This does not mean "don't assume the existence of anything that does could possibly not exist"... what it means is: in a situation where you are trying to explain something, and you have more than one explanation to choose from... and all explanations provide a satisfactory resolution, then using a simple explanation that requires fewer/less complicated assumptions, is the preferable one.
    – MichaelK
    Commented Jun 4, 2018 at 12:03

I am not sure what the majority view is on this matter in philosophy and equally unsure what difference numbers and majorities make in intellectual debate.

What is relevant is to examine the credentials of the presumption. Donald Evans argues that there is a flaw in Flew's use of it. Specifically, that Flew does not observe a sufficiently firm distinction between procedural and substantive presumption. Flew can hardly be ignored since he first propounded the presumption of atheism at least in its current form :

Let us consider Flew's main contention, that the onus of proof lies on the theist. The "proof" which is required of the theist involves (a) showing that his concept of God is such that the existence of God is theoretically possible and (b) providing sufficient reasons, though not necessarily a demonstration, to warrant believing that God exists. The "onus" which is on the theist does not preclude the possibility of a theistic proof. It is similar to the "onus" which is on the prosecutor in an English court: it is up to the prosecutor to prove guilt, but such proof is possible. And just as the prosecutor does not have to drop his personal conviction - if he has one - that the defendant is guilty, the theist does not have to drop hrs own theistic belief. What Flew is asking the theist to do is to accept a procedure. Like the affirmative side in a debate, the theist is asked to concede that if he has not provided grounds for what he affirms, he has lost the debate - whether or not the opposition says anything. If a theist moves, "Resolved that this house affirms the existence of God", the presumption in the debate is atheistic; the theist has to prove his claim or lose the debate. He is like a prosecutor in a court where the procedural rule is that innocence is presumed; the prosecutor must prove guilt or lose his case. Flew holds that the presumption of atheism is a better procedure than the presumption of theism, where the atheist would affirm, "Resolved that this house affirms the non-existence of God", and the atheist would have to prove his claim or lose the argument.

This, if I understand him correctly, is what Flew means when he calls for a purely procedural "presumption of atheism", and insists that the concession asked of the theist is procedural rather than substantive. It seems to me, however, that he does not maintain a firm distinction between a procedural presumption, which is a rule governing a debate or a court or a philosophical dialogue, and a personal presumption, which is a man's own (substantive) convictional stance. A personal presumption that p is a presuming that p is true unless and until adequate contrary evidence is produced. (It differs from a "categorical assumption" that p, which for Flew is (apparently) either a procedural or a personal assumption which precludes the possibility that p is false.) Flew blurs the distinction between procedural and personal presumptions of atheism early in his essay: he first introduces the "presumption of atheism" as a presumption "that the onus of proof must lie on the theist"; then he explains that the "atheism" in this presumption is a "negative atheism"; and then he says that a negative atheist is "someone who is simply not a theist" (that is, presumably, someone who personally presumes atheism). This would preclude theists from taking part in the very debate which Flew asks them to initiate! This is, I think, a slip, for Flew's main line of thought in the essay is such that he supposedly allows a theist personally to presume theism - even to assume theism categorically - while presuming atheism procedurally. (Donald Evans, 'A Reply to Flew's "The Presumption of Atheism"', Canadian Journal of Philosophy, Vol. 2, No. 1 (Sep., 1972), pp. 47-50: 47-8.)

  • Just in case... did you spell check between "theist", "atheist", "a theist", "a atheist", and "an atheist"? Commented Dec 12, 2018 at 16:15
  • I quoted Evans, that is all. Sorry, I am not clear what point you are making.
    – Geoffrey Thomas
    Commented Dec 12, 2018 at 16:35
  • Just trying to make sure that typing errors don't result in "a theist" instead of "atheist" somewhere in there... Commented Dec 12, 2018 at 16:56
  • Thanks - I can't see an example of 'atheist' occurring where 'a theist' is meant. I appreciate your alerting me to the possibility. Is it your impression that there is a case of this ? Clearly, if so, I'd be glad to know. Best - GLT
    – Geoffrey Thomas
    Commented Dec 12, 2018 at 18:24
  • I was reading it and got worried... I needed to trust the copy-validity to process the logic. No, I don't suspect any particular sentence. Commented Dec 12, 2018 at 18:27

The "presumption of Atheism", per Wikipedia, was not accepted by Flew's peers for 3 decades:

Flew's proposal to change his profession's use of the term atheism saw limited acceptance in the 20th century, but in the early 21st century Flew's negative sense of 'atheism' came to be forwarded more commonly.[27][28] The impact of Flew's proposed negative atheism, which is often referred to today as 'weak atheism' or 'soft atheism', is illustrated by analytic Philosopher William Lane Craig's 2007 assessment that the presumption of atheism had become "one of the most commonly proffered justifications of atheism."[29] And BBC journalist William Crawley 2010 analysis: "The Presumption of Atheism (1976) made the case, now followed by today's new atheism, that atheism should be the ... default position".[30][31] In recent debates, atheists often forward the Presumption of Atheism referring to atheism as the "default position"[32][33][34][35] or has "no burden of proof"[36][37] or asserting that the burden of proof rests solely on the theist.[26][38][39]

If one accepts the principle of sufficient reason, then every position, either for or against accepting a thesis, needs to be justified. This is illustrated in the following diagram:

Logic of evaluating a claim

Per the PSR, the "presumption of atheism" is a fallacy of shifting the burden of proof.

Flew himself argued strong agnosticism -- that Theism is incoherent, and this was his justification for atheism. Upon the publication of Swinburne's "The Coherence of Theism", Flew admitted his claim to incoherence was untrue, and this opened him to considering theism. By the end of his life, he had adopted deism. The publication of ghost-written books under his name, which trended toward theism rather than deism, are suspect, given his advancing age and declining faculties.

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