dspeyer comments on Your existence is informative - Less Wrong

2 Post author: KatjaGrace 30 June 2012 02:46PM

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Comment author: dspeyer 30 June 2012 04:04:27PM 4 points [-]

Isn't "I observe X" equivalent to "someone chosen for reasons unrelated to this observation observed X"? That solves the "at some point somebody will make most mistaken measurements" problem because the likelihood of randomly choosing the scientist making that mistake is small.

You can't use this logic for observations of the form "I'm alive" because if you weren't alive you wouldn't be observing. What you can use that as evidence of is a hard problem. But it isn't a general problem.

Comment author: KatjaGrace 30 June 2012 06:15:32PM *  1 point [-]

Perhaps, but then there is the question of how you should pretend they were chosen. This is controversial.

If you weren't alive you wouldn't be observing "I'm alive". If X wasn't true you wouldn't be observing X. Could you be more clear on how you think the logic differs?

Comment author: dspeyer 30 June 2012 08:09:12PM 0 points [-]

Slight double-meaning in the word observing:

When I said "if you weren't alive you wouldn't be observing" I meant you wouldn't be seeing whether you were alive or not.

When you said "If X wasn't true you wouldn't be observing X" you meant you wouldn't be seeing that X is true.

I'm finding my second paragraph surprisingly hard to reword.

Comment author: KatjaGrace 01 July 2012 11:21:00PM 0 points [-]

If your existence depends on X, there are two possibilities: you observe X, you observe nothing

If your existence doesn't depend on X but you have some other way of observing whether X is true, the possibilities are: you observe X, you observe not X.

Do you think that observing X provides different information about something else in these two cases?