5 ms·

I suppose this is a bad place to ask this, but given that you need to do math to update your credences and also that you can derive any proposition from Pr('2 +

I suppose this is a bad place to ask this, but given that you need to do math to update your credences and also that you can derive any proposition from Pr('2 + 2 = 4) != 1, how does this work?

derefr 10y ago
Basically: probabilities and credences aren't the same thing. They're measured on the same scale, but probabilities can be used to reason about either facts or evidence, while credences are only "about" evidence (though potentially evidence about facts.) To put that another way: it is "100% true" that 2 + 2 = 4 (in ZF set theory); just like it is "100% true" that the sun will rise today, because it already did (and otherwise the Monty Hall problem would have a different answer.) But the credence in an agent's mind can and should only be informed by observations of these facts; and the "observing hardware" cannot be 1.0 trustworthy. (Your senses can be imprecise; the brain can be buggy or biased; the environment being observed can be the construction of a Cartesian "evil demon"; etc.) Given an artificial agent with perfect knowledge (e.g. one who is able to directly entangle itself with the environment it is trying to predict, rather than just one able to entangle itself with evidence about the state of an environment), some things can theoretically be held to have 0.0 or 1.0 probabilities (e.g. events that already happened)—but given an embodied agent, the "maybe my processing is flawed" argument should still make these into non-infinite credences.
- hyperpape 10y ago
  Thanks. I should've remembered that the connection to an agent's credences and their judgments of probabilities is complicated.
- platz 10y ago
  If the Higgs field quantum tunnels to a lower energy level today in our vincinity, the sun will not rise tomorrow. Never put 100%
  - derefr 10y ago
    I didn't say "the sun will rise tomorrow"; I said "the sun will rise today"—as in, the (trivial) probability that the sunrise that already happened, will happen, looking forward from the more distant past to the more recent past. Given that we are talking about the probability of that event occurring from a reality where it occurred, the updated probability of it occurring is 100%. (But we cannot have 100% credence, simply because we can't actually be 100% sure we're in said reality.)

I suppose this is a bad place to ask this, but given that you need to do math to update your credences and also that you can derive any proposition from Pr('2 + 2 = 4) != 1, how does this work?

derefr 10y ago

Basically: probabilities and credences aren't the same thing. They're measured on the same scale, but probabilities can be used to reason about either facts or evidence, while credences are only "about" evidence (though potentially evidence about facts.) To put that another way: it is "100% true" that 2 + 2 = 4 (in ZF set theory); just like it is "100% true" that the sun will rise today, because it already did (and otherwise the Monty Hall problem would have a different answer.) But the credence in an agent's mind can and should only be informed by observations of these facts; and the "observing hardware" cannot be 1.0 trustworthy. (Your senses can be imprecise; the brain can be buggy or biased; the environment being observed can be the construction of a Cartesian "evil demon"; etc.) Given an artificial agent with perfect knowledge (e.g. one who is able to directly entangle itself with the environment it is trying to predict, rather than just one able to entangle itself with evidence about the state of an environment), some things can theoretically be held to have 0.0 or 1.0 probabilities (e.g. events that already happened)—but given an embodied agent, the "maybe my processing is flawed" argument should still make these into non-infinite credences.

hyperpape 10y ago
Thanks. I should've remembered that the connection to an agent's credences and their judgments of probabilities is complicated.
platz 10y ago
If the Higgs field quantum tunnels to a lower energy level today in our vincinity, the sun will not rise tomorrow. Never put 100%
- derefr 10y ago
  I didn't say "the sun will rise tomorrow"; I said "the sun will rise today"—as in, the (trivial) probability that the sunrise that already happened, will happen, looking forward from the more distant past to the more recent past. Given that we are talking about the probability of that event occurring from a reality where it occurred, the updated probability of it occurring is 100%. (But we cannot have 100% credence, simply because we can't actually be 100% sure we're in said reality.)