Certain atheists in the mid-twentieth century were promoting the so-called presumption of atheism. At face value, this would appear to be the claim that in the absence of evidence for the existence of God, we should presume that God does not exist. Atheism is a sort of default position, and the theist bears a special burden of proof with regard to his belief that God exists.
So understood, such an alleged presumption is clearly mistaken. For the assertion that There is no God is just as much a claim to knowledge as is the assertion that There is a God. Therefore, the former assertion requires justification just as the latter does. It is the agnostic who makes no knowledge claim at all with respect to Gods existence. He confesses that he doesnt know whether there is a God or whether there is no God.
But when you look more closely at how protagonists of the presumption of atheism used the term atheist, you discover that they were defining the word in a non-standard way, synonymous with non-theist." So understood the term would encompass agnostics and traditional atheists, along with those who think the question meaningless (verificationists). As Antony Flew confesses,
the word atheist has in the present context to be construed in an unusual way. Nowadays it is normally taken to mean someone who explicitly denies the existence . . . of God . . . But here it has to be understood not positively but negatively, with the originally Greek prefix a- being read in this same way in atheist as it customarily is in . . . words as amoral . . . . In this interpretation an atheist becomes not someone who positively asserts the non-existence of God, but someone who is simply not a theist. (A Companion to Philosophy of Religion, ed. Philip Quinn and Charles Taliaferro [Oxford: Blackwell, 1997], s.v. The Presumption of Atheism, by Antony Flew)
Such a re-definition of the word atheist trivializes the claim of the presumption of atheism, for on this definition, atheism ceases to be a view. It is merely a psychological state which is shared by people who hold various views or no view at all. On this re-definition, even babies, who hold no opinion at all on the matter, count as atheists! In fact, our cat Muff counts as an atheist on this definition, since she has (to my knowledge) no belief in God.
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Definition of atheism | Reasonable Faith
