This is an excellent point, an implication that I ought to have deduced myself but totally didn’t. This means not only that absolute certainty about reality is impossible to get, but more interestingly that absolute certainty about reality is entirely useless as it can’t make specific predictions. Even if it were something like “can’t go faster than the speed of light”, being absolutely certain of this would mean that “scientists measuring something going faster than the speed of light because of experimental error” would be a valid prediction, along with “it is an illusion/I am crazy”. Since neither experimental result would disprove the certain thing, it must follow that the certain thing can’t predict the experimental result.
In fact, I think we can claim that the probability that you’re sane, should be an upper bound on probabilities you’re allowed to claim. Thus to claim arbitrarily high probabilities, you’d need an arbitrarily large group of probably sane people who agree (but then what are the odds that you just imagined the group of people who agree with you?). Since you can’t be absolutely certain that you and all your group are perfectly sane (along with the possibility of a coincidentally matching mass hallucination), that would make for an upper bound on certainty. In fact the whole group thing would be unnecessary if we admit the possibility that the person we’re trying to convince might be insane.
Next time someone claims absolute certainty about something, I’ll ask them to prove that they’re not insane. That should take them into neutral territory that they haven’t had time to wall up, and if they did consider that they might be insane it would be an even better argument.
This is an excellent point, an implication that I ought to have deduced myself but totally didn’t. This means not only that absolute certainty about reality is impossible to get, but more interestingly that absolute certainty about reality is entirely useless as it can’t make specific predictions. Even if it were something like “can’t go faster than the speed of light”, being absolutely certain of this would mean that “scientists measuring something going faster than the speed of light because of experimental error” would be a valid prediction, along with “it is an illusion/I am crazy”. Since neither experimental result would disprove the certain thing, it must follow that the certain thing can’t predict the experimental result.
In fact, I think we can claim that the probability that you’re sane, should be an upper bound on probabilities you’re allowed to claim. Thus to claim arbitrarily high probabilities, you’d need an arbitrarily large group of probably sane people who agree (but then what are the odds that you just imagined the group of people who agree with you?). Since you can’t be absolutely certain that you and all your group are perfectly sane (along with the possibility of a coincidentally matching mass hallucination), that would make for an upper bound on certainty. In fact the whole group thing would be unnecessary if we admit the possibility that the person we’re trying to convince might be insane.
Next time someone claims absolute certainty about something, I’ll ask them to prove that they’re not insane. That should take them into neutral territory that they haven’t had time to wall up, and if they did consider that they might be insane it would be an even better argument.