Why "is evidence for" is a symmetric relation
0Apr 29, 2021
alex_hhr
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If you generate predictions by looking up market values, that means three things:
Because of (2), if everyone did this, there would be no market.
You need your own machine for generating predictions. Here, I'm borrowing a metaphor from Ronny Fernandez, who says that he keeps track of predictions because he needs to debug the program that generates them.
You don't need to believe the resulting predictions. You can make predictions like, "I think that the probability of a Trump re-election is... (read more)
"Statistical models with fewer assumptions" is a tricky one, because the conditions under which your inferences work is not identical to the conditions you assume when deriving your inferences.
I mostly have in mind a historical controversy in the mathematical study of evolution. Joseph Felsenstein introduced maximum likelihood methods for inferring phylogenetic trees. He assumed a probabilistic model for how DNA sequences change over time, and from that he derived maximum likelihood estimates of phylogenetic trees of species based on their DNA sequences.
Felsenstein's maximum likelihood method was an alternative to another method, the "maximum parsimony" method. The maximum parsimony tree is the tree that requires you to assume the fewest possible sequence changes... (read more)
My view of the Copernican revolution used to be that when people finally switched to the heliocentric model, something clicked. The data was suddenly predictable and understandable.
It sounds like this is what happened though, but the click was at Kepler.
The surprising corollary is that Galileo just happened to be right, and I don't really want to imitate him. I don't want to be the kind of person who would have been a Copernican without knowing Kepler's theory.
But on the other hand, to invent Kepler's theory, Kepler had to be a Copernican.
As I was reading I kept waiting for gills to be mentioned, and then it was satisfying to see that it was one of the two un-dolphinlike characteristics in the dictionary definition. I figured, if someone asks me "how do fish get oxygen if they live underwater?" I'm going to say "because they have gills," not "because they either have gills or return to the surface to breath."
But then, vaniver's comment mentioning sharks got me thinking. What if someone asks "do fish have bones?" The more I think about it, the harder it is for me to think of sharks as the same kind of thing as salmon.
I don't know what lesson to draw from this, except that I find it uncomfortable, want better words, and am suddenly motivated to learn fish taxonomy, a subject that never interested me before, just for vocabulary that leaves me more mentally comfortable.