1. You remember that you did. Memory serves as a bank of perceptual information. Neural stimuli built up throughout years of schooling can provide sufficient evidence that you attended school in the 1990s. This confirmation method can be disregarded in cases of prolonged hypnosis, brainwashing, drug abuse, head trauma, electroconvulsive therapy, neuropsychiatric disease, and/or if you have ever entered an extended fugue state.
2. You are told explicitly by a trusted person. Trusted people could include your parents, siblings, mentors, the President, or a longtime friend. Asking the person to repeat him or herself, or to put the statement in writing reduces the possibility of an auditory hallucination. You [...]