The argument from religious experience takes personal experiences apparently of God as a reason to believe that God exists. One difficulty with this argument is that religious experiences are subjective, and it is notoriously difficult to use subjective experiences to justify objective claims about the world.

Mental events are by their very nature private; though I may be able to glean some information about what you’re thinking from the things that you say and do, I cannot directly observe what is happening in your mind. This, arguably, undermines the evidential value of religious experiences.

Religious Experiences are Unverifiable

One way of putting this argument is as an appeal to verifiability.

For something to count as evidence, it must be publicly accessible so that it can be tested. Religious experiences, though, are not publicly accessible, and so cannot be tested; they therefore cannot count as evidence for religious belief.

Religious Experiences are Ineffable

A further problem for the argument from religious experience is raised by the fact that religious experiences are often ineffable. It is bad enough that when someone who has had a religious experience tries to describe it to us we cannot verify whether what they are describing really happened; it is worse that due to the ineffability of religious experiences someone who has had a religious experience cannot describe it at all.

A J Ayer noted this, writing: “… if a mystic admits that the object of his vision is something which cannot be described, then he must also admit that he is bound to talk nonsense when he describes it… in describing his vision the mystic does not give us any information about the external world: he merely gives us indirect information about the condition of his own mind.”

An advocate of the argument from religious experience could accept all this, but hold that religious experiences can count as evidence for those that have those experiences, even if not for anyone else. It may be that I cannot prove to you that I had a religious experience, or even describe that experience to you, and so that my experience cannot count for you as evidence of God’s existence; for me, though, who knows that the experience is real and who does not need to describe it in order to understand it, my experience may provide a basis for rational belief.

Verifying one’s own religious experiences, however, can be just as problematic as verifying someone else‘s. Thomas Hobbes asked what the difference is between saying “God spoke to me in a dream” and saying “I dreamt that God spoke to me.”

The problem is that religious experiences are merely mental events, and there is therefore no logical problem with our having these experiences without the world being as they represent it to be. We could just as readily doubt our own religious experiences, asking “Was I hallucinating?”, “Am I putting my own interpretation onto something mundane?”, “Was it something I ate?”, as anyone else‘s. It seems, therefore, that we can never be sure enough of a religious experience to prove anything objective about the world.