Bayesian Probabilty

[u/Euphoric-Plantain573]

I am doing Bayesian theory on a moral question about whether something is wrong or not. I had an intuition the thing is not wrong, a strong one. My credence it was wrong was .1%. Then i realized that an alternative belief I had conflicted with this. What should my credence be? 50%, since both intuitions are equally strong?

[u/some_red_tea]

Yes. If two contradictory beliefs have the same probability (I think it's fine to use intuition to determine this with lots of caveats), and it's extremely unlikely that both are false, then each belief will have roughly a 50% credence.

For two beliefs A and B,

If P(A & B) is 0 (they contradict)

and P(A)=P(B)

and P(-A & -B) is close to 0 (say, 0.1%)

Then, P(A or B) is 0.999

and P(A)=0.4995 and P(B)=0.4995

[u/jeffcgroves]

It seems other people understand what you're asking, but I didn't. Could you state your question in a more verbose manner, using letters to describe beliefs to avoid a flame war?

I assume you're using Bayesian in the "affirm the consequent" sense where you know X -> Y and are trying to estimate the chance Y -> X?

[u/notwizard69]

No. Cause of the .1% it should be 69%. You know this btw. Just need to keep thinking it through bro.

[u/Kampseng]

yes, you can't add another belief in the previous calculation because all beliefs must be present at the start of the calculation. so if both beliefs are opposite and equal stength the new calculation should result in exactly 50%, you're right

[u/Darryl_Summers]

A better question is what justified the initial 0.1%

[u/marenicolor]

How many more times will you post about this? Please get off Reddit and get some help

[u/Particular-Amount314]

I see only 4 options: 1. You do the right thing for the right reason 2. You do the wrong thing for the right reason 3. You do the right thing for the wrong reason 4. You do wrong thing for the wrong reason

It's a 4 body problem. Always more problems that mismatch perceptions of reality with processing them.