Evidentialism and the Burden of Proof

By: Michelle Zorzella



Faith is commonly defined by nonbelievers as belief without evidence. In the words of the late Christopher Hitchens, “That which can be asserted without evidence, can be dismissed without evidence.” (God Is Not Great: How Religion Poisons Everything, 2007). According to some atheists, the lack of evidence in favour of the existence of gods indicates a belief in such an entity is irrational. This argument is representative of evidentialism: the idea that conclusions are only rational (or justified) if supported by evidence. Understood, it is a theory that applies to all doxastic attitudes including belief, disbelief and suspension of judgment. With this point in mind, the question arises: if belief in gods can be deemed irrational on the ground of evidentialism, can atheism also be dismissed if it is not based on evidence? A number of atheists who reject theism on the basis of evidentialism argue their atheism does not need to be supported by evidence. Although they offer arguments in support of this position, the reasons provided ultimately fail to justify this double standard.

Rejection of Theism

Since the atheist rejects the proposition P god(s) exist, only those who accept P have the responsibility of defending their belief. In other words, evidence is not needed to justify their position because the burden of proof is on “the believer.” They further contend (in contrast to those who argue the absence of evidence is evidence of absence) they do not assume failure to justify theism is a reason to conclude no gods exist. It is unclear how someone can be justified purely on the basis of rejecting another claim. This would seem to lead to absurdities; is one justified in not believing the earth is a spheroid, so long as they merely deny the existence of any evidence? Not without refusing to entertain any contrary evidence readily made available by believers. Moreover, this argument cannot be taken to mean no evidence is needed to justify atheism since evidentialism applies to all doxastic attitudes. This factor alone should encourage atheists who ascribe to evidentialism to seek evidence for all attitudes of belief concerning the existence of gods.

The Presumption of Atheism

Anthony Flew argues in his work The presumption of Atheism, that “the debate about the existence of God should properly begin from the presumption of atheism, that the onus of proof must lie upon the theist.” He compares this principle to the Presumption of Innocence, which according to English law, holds one is legally innocent until proven guilty. From this presumption, it follows the defence is not necessarily required to prove or disprove any fact, since it is sufficient for exoneration that the evidence put forth by the prosecution fails to meet the burden of proof. The nonbeliever likewise asserts that, until the theist has satisfied their burden, it is safe to presume gods probably do not exist.

It is worth it to entertain this argument given there is a reason to presume atheism in the first place? A presumption of innocence is necessary in a court of law to ensure the accused is tried fairly; that is to say, if a court wants to hold someone criminally liable they must persuade a trier of fact with good evidence that the accused is indeed guilty. On the contrary, failing to proceed on the presumption of atheism does not appear to bring about any considerable consequences that then obligates one to implement a permanent burden solely on the theist. This point is especially important for the evidentialist who holds all attitudes of belief are irritational unless they can be substantiated by evidence. The presumption of atheism alone does not establish any reason to say atheism is rational or justified without evidence.

The Null Hypothesis

The null hypothesis is a default position formally used in inferential statistics for hypothesis testing. Broadly speaking, it asserts any observed outcome associated with a predicted variable is due to chance alone. Formulating a null hypothesis to test a prediction helps to establish a degree of probability that can then be used to estimate whether the initial prediction is true. Bearing this in mind, a number of nonbelievers argue atheism is comparable to a null hypothesis. Assuming this is true, and they are indeed similar in some relevant way, the arguer should offer proof of the probability that theism is true, thus providing a basis to accept or deny atheism. After all, scientists do not assert a hypothesis without any intent to substantiate it. Therein lies a profound problem: surely there is a burden on the nonbeliever offering a null hypothesis to not just develop a model and context for experimentation, but to establish a degree of probability that justifies accepting atheism. To solve this problem, some atheists claim naturalism (the idea that natural phenomena have natural causes) is the null hypothesis. To put that differently, the nonbeliever is philosophically justified in presuming atheistic naturalism, just as a natural scientist presumes methodological naturalism. Still, this defence begs the question as to why the arguer has presumed atheism to begin with since naturalism is not inherently atheistic. While the null hypothesis argument (much like the presumption of atheism) attempts to shift the burden of proof on to the theist, it fails to demonstrate how one is justified in accepting atheism without some proof of probability.

Proving a Negative

Some atheists argue that evidence for atheism cannot be provided because it is impossible—or at least unreasonable—to prove a negative. The underlying premise here immediately arouses suspicion since the argument itself cannot be proven, given its grammatically negative. Furthermore, if one means by “proof” evidence or reasons which serve to substantiate a statement of truth, it is possible to conceive how proof can be demonstrated for several negative claims. To start, a null hypothesis is generally phrased as a negative proposition, yet it can be sufficiently justified by demonstrating inductive probability. To give another example, it can reasonably be demonstrated that “Brad Pitt is not currently in my home” or that “four is not a prime number; evidence of absence or proof of impossibility is sufficient justification here. A variation of this argument suggests the idea one cannot prove a negative only applies to existential statements. Even then, nonexistence can be demonstrated reasonably through observation, as well as by proof of contradiction or incompatibility. In truth, proving a negative is no more difficult than proving a positive, especially when it comes to the existence of gods. The argument one cannot prove a negative is false and does not substantiate the claim that evidence is not needed to justify atheism. Even more, it suggests that one cannot falsify claims in general, as the aim of falsification is to prove a negative.

Agnostic Atheism

Many agnostic atheists assert that because they do not claim to know with any certainty whether or not gods exist, evidence is not required to substantiate their lack of belief. Essentially this means there is no necessity for an agnostic to justify holding to atheism. Ignore for argument sake that evidentialism should nonetheless apply to a suspension of judgment, but consider the idea that agnosticism strictly concerns knowledge whereas atheism pertains to belief. For the atheist to admit having no knowledge that justifies belief in atheism is rather self weakening given evidentialism is a theory of what it takes to believe something justifiably. Put differently, if one cannot assert atheism is true or that one can justifiably believe in atheism, there is little reason for an evidentialist to accept it. At the same time, several agnostic atheists claim either beliefs do not require justification, or that they only require justification when one is confident the belief is true. In either case, the atheist then has no personal reason to dismiss theism unless it is believed to be true. What this means is, while the arguer can dismiss that which a theist claims to know without justification, it would not follow that the arguer should altogether dismiss theism within their own reasoning, given they do not hold it to be a true belief. All things considered, the question still remains why the arguer has even presumed atheism to begin with (see “Atheism and Agnosticism” for more on this subject).


An evidentialist approach to epistemic justification suggests that atheism should be dismissed if it is not based on evidence. Although a number of atheists say no evidence is needed to justify their position, the reasons provided fail to support this presumption. While it might be arguably appropriate to allow the burden of proof to begin with the believer during a debate, this does not negate the necessity for the evidentialist to dismiss all attitudes of belief that are not substantiated by evidence. As Flew rightfully points out, by proceeding on the presumption of atheism “the theist who wants to build a systematic and thorough apologetic finds that he is required to begin absolutely from the beginning.” When a burden of proof is likewise on the atheist, the nonbeliever is forced to start from the beginning and subject atheism to an equally rigorous process of justification. Ultimately evidentialism applies to all doxastic attitudes, including belief, disbelief and suspension. Atheism should be granted no exception.

[1]Flew, Antony. “The Presumption of Atheism.” Canadian Journal of Philosophy, vol. 2, no. 1, 1972, pp. 29–46.

[2] “presumption of innocence.” West’s Encyclopedia of American Law, edition 2. 2008. The Gale Group 14 Jul. 2016 <http://legal-dictionary.thefreedictionary.com/presumption+of+innocence>

[3] Null Hypothesis (H0)


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