Glossary: Theism, Atheism, and Agnosticism

The terms “theist”, “atheist”, and “agnostic”, though widely used, can be particularly confusing. This is largely because often different people use these terms in different ways. Below, the various common definitions of “theism”, “atheism”, and “agnosticism” are explained.

Definition: “Theist”

Theism is the least problematic of the three terms defined here; it is the belief in a god or gods. Classical theism is belief in one God, and involves affirming certain theistic doctrines about his nature. The doctrine of divine omnipotence, for instance, holds that God is all-powerful; the doctrine of divine omniscience that he is all-knowing. Other doctrines affirm God’s immutability (unchangeability), eternity (timelessness), impassibility (freedom from passions), and aseity (self-sufficiency). Someone who believes in all or most of these doctrines is a classical theist; someone who believes in a god but does not conceive of it in this way is a theist, but not a classical theist. Such non-classical theists include pantheists, who believe that everything is God, that God is identical with the universe.

Definition: “Atheist”

Atheism is usually taken to be belief that god does not exist. More recently, however, some atheists have attempted to define atheism in more cautious terms, as nothing more than the absence of belief in God. This has complicated matters, introducing an ambiguity into the definition of “atheism”. One solution to this ambiguity is to distinguish between “weak atheism” and “strong atheism”.

Weak atheism is defined as the absence of belief in God. On this definition, strictly speaking, anyone who isn’t a theist is an atheist. Someone who doesn’t have an opinion about religion, having never really thought about it, lacks belief in God and is therefore a weak atheist. Someone who has thought about religion, but hasn’t reached any conclusions about it, lacks belief in God, and is therefore a weak atheist. Someone who has thought about religion, and has reached the provisional, tentative conclusion that God doesn’t exist, lacks belief in God and is therefore a weak atheist. And someone who confidently and dogmatically affirms that there is no God, lacks belief in God and is therefore a weak atheist.

A strong atheist, on the other hand, is someone who has the positive belief that God does not exist. It is not necessary to feel complete certainty that God does not exist in order to be a strong atheist; the essential difference between strong atheism and weak atheism is that strong atheism is defined in terms of possession of the belief that God does not exist, while weak atheism is defined in terms of absence of the belief that God does exist.

Technically, then, every strong atheist will also be a weak atheist, though not every weak atheist will be a strong atheist. Everyone who believes that God does not exist will lack belief that God does exist, but not everyone who lacks belief that God does exist will possess the positive belief that God does not exist. In practice, however, weak atheism and strong atheism are taken to be mutually exclusive; one cannot be both a weak atheist and a strong atheist. A weak atheist is therefore someone who both lacks belief that God does exist and lacks belief that God does not exist. Weak atheists are thus what people often refer to as “agnostics”.

Definition: “Agnostic”

Agnosticism is usually used to describe what has above been called “weak atheism”, indecision as to whether or not God exists. Although this is the most common conception of agnosticism, it is not its original sense, nor its classical sense. This view of agnosticism has occasionally been called “weak agnosticism”.

The term “agnosticism” was coined by Thomas Huxley. For Huxley, agnosticism was a rational method: proportion one’s belief to the evidence. An agnostic, on this view, is someone who does not claim certainty when all that is available is probability, someone who measures their beliefs to the strength of their reasons for so believing.

Agnosticism in this second sense is consistent with both theism and atheism. If the evidence establishes theism, then one who believes in accordance with the evidence will be both an agnostic and a theist. Similarly, if the evidence establishes atheism, then one who believes in atheism will be both an agnostic and an atheist.

Classically, however, agnosticism has carried a different meaning both to its common meaning now and to the sense in which its inventor used it. Classically, an agnostic is someone who not only is undecided concerning the existence of God, but who also thinks that the question of God’s existence is in principle unanswerable. We cannot know whether or not God exists, according to an agnostic, and should therefore neither believe nor disbelieve in him.

Definitions