What is the definition of agnosticism? An agnostic is anyone who doesn't claim to know that any gods exist or not. Some imagine that agnosticism is an alternative to atheism, but those people have typically bought into the mistaken notion of the single, narrow definition of atheism. Strictly speaking, agnosticism is about knowledge, and knowledge is a related but separate issue from belief, which is the domain of theism and atheism.

Agnostic - Without Knowledge

”A” means “without” and “gnosis” means “knowledge.” Hence, agnostic: without knowledge, but specifically without knowledge of. It may be technically correct, but rare, to use the word in reference to any other knowledge as well, for example: “I am agnostic about whether O.J. Simpson actually killed his ex-wife.”

Despite such possible usages, it remains the case that the term agnosticism is used fairly exclusively with respect to a single issue: do any gods exist or not? Those who disclaim any such knowledge or even that any such knowledge is possible are properly labeled agnostics. Everyone who claims that such knowledge is possible or that they have such knowledge might be called “gnostics” (note the lowercase ‘g’).

Here “gnostics” is not referring to the religious system known as Gnosticism, but rather the sort of person who claims to have knowledge about the existence of gods. Because such confusion may come easily and because there is generally little call for such a label, it is unlikely that you will ever see it used; it is only presented here as a contrast to help explain agnosticism.

Agnosticism Doesn't Mean You're Just Undecided

Confusion about agnosticism commonly arises when people assume that “agnosticism” actually just means that a person is undecided about whether or not a god exists, and also that “atheism” is limited to “strong atheism” — the assertion that no gods do or can exist. If those assumptions were true, then it would be accurate to conclude that agnosticism is some sort of “third way” between atheism and theism. However, those assumptions are not true.

Commenting on this situation, Gordon Stein wrote in his essay “The Meaning of Atheism and Agnosticism”:

Obviously, if theism is a belief in a God and atheism is a lack of a belief in a God, no third position or middle ground is possible. A person can either believe or not believe in a God. Therefore, our previous definition of atheism has made an impossibility out of the common usage of agnosticism to mean “neither affirming nor denying a belief in God.” The literal meaning of agnostic is one who holds that some aspect of reality is unknowable. Therefore, an agnostic is not simply someone who suspends judgment on an issue, but rather one who suspends judgment because he feels that the subject is unknowable and therefore no judgment can be made. It is possible, therefore, for someone not to believe in a God (as Huxley did not) and yet still suspend judgment (ie, be an agnostic) about whether it is possible to obtain knowledge of a God. Such a person would be an atheistic agnostic. It is also possible to believe in the existence of a force behind the universe, but to hold (as did Herbert Spencer) that any knowledge of that force was unobtainable. Such a person would be a theistic agnostic.

Philosophical Agnosticism

Philosophically, agnosticism can be described as being based upon two separate principles. The first principle is epistemological in that it relies upon empirical and logical means for acquiring knowledge about the world. The second principle is moral in that it insists that we have an ethical duty not to assert claims for ideas which we cannot adequately support either through evidence or logic.

So, if a person cannot claim to know, or at least know for sure, if any gods exist, then they may properly use the term “agnostic” to describe themselves; at the same time, this person likely insists that it would be wrong on some level to claim that gods either definitely do or definitely don’t exist. This is the ethical dimension of agnosticism, arising from the idea that a strong atheism or strong theism is simply not justified by what we currently know.

Although we now have an idea of what such a person knows or thinks she knows, we don’t actually know what she believes. As Robert Flint explained in his 1903 book "Agnosticism ," agnosticism is:

...properly a theory about knowledge, not about religion. A theist and a Christian may be an agnostic; an atheist may not be an agnostic. An atheist may deny that there is God, and in this case his atheism is dogmatic and not agnostic. Or he may refuse to acknowledge that there is a God simply on the ground that he perceives no evidence for his existence and finds the arguments which have been advanced in proof of it invalid. In this case his atheism is critical, not agnostic. The atheist may be, and not infrequently is, an agnostic.

It is a simple fact that some people don’t think that they know something for sure, but believe anyway and that some people cannot claim to know and decide that that is reason enough to not bother believing. Thus agnosticism is not an alternative, “third way” going between atheism and theism: it is instead a separate issue compatible with both.

Agnosticism for Both Believers and Atheists

As a matter of fact, a majority of people who consider themselves either atheist or theist might also be justified in calling themselves agnostics. It is not at all uncommon, for example, for a theist to be adamant in their belief, but also be adamant in the fact their belief is based on faith and not on having absolute, incontrovertible knowledge.

Moreover, some degree of agnosticism is evident in every theist who considers their god to be “unfathomable” or to “work in mysterious ways.” This all reflects a fundamental lack of knowledge on the part of the believer with regards to the nature of what they claim to believe in. It might not be entirely reasonable to hold a strong belief in the light of such acknowledged ignorance, but that rarely seems to stop anyone.