‘Why do you doubt your senses?’ said Marley’s ghost.
‘Because,’ said Scrooge, ‘a little thing affects them. A slight disorder of the stomach makes them cheats. You may be an undigested bit of beef, a blot of mustard, a crumb of cheese, a fragment of an underdone potato. There’s more of gravy than of grave about you, whatever you are!’
—Charles Dickens, A Christmas Carol
Recently I read a book about yoga by Swami Vivekananda. In it, the swami puts forward the common argument in favor of mystical truth: that direct experience of the super-sensuous realm—the spiritual plane—can attest to its existence. That is, the existence of the spiritual plane, while it cannot be detected with any technological device, deduced from any scientific theory, or proven on any philosophical grounds, can be known for certain to exist via direct experience.
I have no doubt that, through yoga, meditation, and prayer, people have had extraordinary experiences. These experiences may well have been far more intense than day-to-day life. On occasion these visions may have left such a lasting mark on a sage’s mind that he was forever transformed, perhaps much for the better.
Since experiences such as these are uncommon and unusual, these gurus will then be faced with the impossible task of capturing their private sensation in words and conveying it to somebody who has never felt anything similar. It would be like describing the color red to a blind man. This is why mystical writing is so often poetical. This also explains why it so often strays into metaphysics.
For my part, I am very fond of mystical poetry. But I have little patience for any epistemology that considers fleeting, incommunicable, and private experiences to be valid sources of insight into the nature of reality. Science works because its methodology does its very best to shun these sorts of visions. Science is effective because it treats knowledge as a social product, not a private hallucination, and because it treats experience as prone to error and in need of interpretation, not as a direct window into reality.
Ebenezer Scrooge was wrong about many things. But he was right to distrust his senses when he thought he saw a ghost. Luckily for him, the reality-status of the ghosts he saw does not make their moral message any less true. Likewise, even if mystical visions and meditative ecstasies may not be valid sources of knowledge about the universe, they can lead to valuable personal transformations.