Agnostic atheism, also called atheistic agnosticism, encompasses atheism and agnosticism. Agnostic atheists are atheistic because they do not have belief in the existence of any deity, and agnostic because they do not claim to know that a deity does not exist. The agnostic atheist may be contrasted with the agnostic theist, who does believe that one or more deities exist but does not claim to have knowledge of such.
One of the earliest definitions of agnostic atheism is that of Robert Flint, in his Croall Lecture of 1887–1888 (published in 1903 under the title Agnosticism).
"The atheist may however be, and not unfrequently is, an agnostic. There is an agnostic atheism or atheistic agnosticism, and the combination of atheism with agnosticism which may be so named is not an uncommon one."
"If a man has failed to find any good reason for believing that there is a God, it is perfectly natural and rational that he should not believe that there is a God; and if so, he is an atheist... if he goes farther, and, after an investigation into the nature and reach of human knowledge, ending in the conclusion that the existence of God is incapable of proof, cease to believe in it on the ground that he cannot know it to be true, he is an agnostic and also an atheist – an agnostic-atheist – an atheist because an agnostic... while, then, it is erroneous to identify agnosticism and atheism, it is equally erroneous so to separate them as if the one were exclusive of the other..."
↑ 1.01.1Flint, Robert (1903). Agnosticism: the Croall Lecture, 1887-1888. William Blackwood and Sons. pp. 49–51.
Martin, Michael. Theism. MSN Encarta, 2000. Microsoft Corporation.
Martin, Michael. Atheism: A Philosophical Justification. Philadelphia: Temple UP, 1992. ISBN 0-87722-943-0
Smith, George H. Atheism: The Case Against God. 1st ed. Amherst: Prometheus Books, 1980. ISBN 0-87975-124-X
Stein, Gordon. The Encyclopedia of Unbelief. Amherst: Prometheus Books, 1985. ISBN 0-87975-307-2