Argument from incredulity is a logical fallacy where someone rejects a claim solely because it seems unbelievable or difficult to imagine. This fallacy assumes that a personal lack of understanding or imagination is evidence that something is false. The perceived improbability of a claim, regardless of actual evidence, is treated as sufficient grounds for dismissing it. Essentially, the arguer substitutes their subjective sense of what is plausible for objective proof.
For example, someone might say, "I can't believe humans landed on the moon. It just seems too impossible. I mean, traveling that far, building a rocket that powerful, it's just unbelievable. It must have been faked." In this example, the speaker rejects the moon landing because they find it difficult to comprehend. The speaker's personal incredulity about the complexity of space travel and the technology involved is used as the sole reason to dismiss the well-established fact of the event.