One way of framing the difficulty with the lanternflies thing is that the question straddles the is-ought gap. It decomposes pretty cleanly into two questions: “What states of the universe are likely to result from me killing vs not killing lanternflies” (about which Bayes Rule fully applies and is enormously useful), and “Which states of the universe do I prefer?”, where the only evidence you have will come from things like introspection about your own moral intuitions and values. Your values are also a fact about the universe, because you are part of the universe, so Bayes still applies I guess, but it’s quite a different question to think about. If you have well defined values, for example some function from states (or histories) of the universe to real numbers, such that larger numbers represent universe states that you would always prefer over smaller numbers, then every “should I do X or Y” question has an answer in terms of those values. In practice we’ll never have that, but still it’s worth thinking separately about “What are the expected consequences of the proposed policy?” and “What consequences do I want”, which a ‘should’ question implicitly mixes together.
You raise an excellent point! In hindsight I’m realizing that I should have chosen a different example, but I’ll stick with it for now. Yes, I agree that “What states of the universe are likely to result from me killing vs not killing lanternflies” and “Which states of the universe do I prefer?” are both questions grounded in the state of the universe where Bayes’ rule applies very well. However, I feel like there’s a third question floating around in the background: “Which states of the universe ‘should’ I prefer?” Based on my inner experiences, I feel that I can change my values at will. I specifically remember a moment after high school when I first formalized an objective function over states of the world, and this was a conscious thing I had to do. It didn’t come by default. You could argue that the question “Which states of the universe would I decide I should prefer after thinking about it for 10 years” is a question that’s grounded in the state of the universe so that Bayes’ Rule makes sense. However, trying to answer this question basically reduces to thinking about my values for 10 years; I don’t know of a way to short circuit that computation. I’m reminded of the problem about how an agent can reason about a world that it’s embedded inside where its thought processes could change the answers it seeks.
If I may propose another example and take this conversation to the meta-level, consider the question “Can Bayes’ Rule alone answer the question ‘Should I kill lanternflies?’?” When I think about this meta-question, I think you need a little more than just Bayes’ Rule to reason. You could start by trying to estimate P(Bayes Rule alone solves the lanternfly question), P(Bayes Rule alone solves the lanternfly question | the lanternfly question can be decomposed into two separate questions), etc. The problem is that I don’t see how to ground these probabilities in the real world. How can you go outside and collect data and arrive at the conclusion “P(Bayes Rule alone solves the lanternfly question | the lanternfly question can be decomposed into two separate questions) = 0.734”?
In fact, that’s basically the issue that my post is trying to address! I love Bayes’ rule! I love it so much that the punchline of my post, the dismissive growth-consistent ideology weighting, is my attempt to throw probability theory at abstract arguments that really didn’t ask for probability theory to be thrown at them. “Growth-consistency” is a fancy word I made up that basically means “you can apply probability theory (including Bayes’ Rule) in the way you expect.” I want to be able to reason with probability theory in places where we don’t get “real probabilities” inherited from the world around us.
One way of framing the difficulty with the lanternflies thing is that the question straddles the is-ought gap. It decomposes pretty cleanly into two questions: “What states of the universe are likely to result from me killing vs not killing lanternflies” (about which Bayes Rule fully applies and is enormously useful), and “Which states of the universe do I prefer?”, where the only evidence you have will come from things like introspection about your own moral intuitions and values. Your values are also a fact about the universe, because you are part of the universe, so Bayes still applies I guess, but it’s quite a different question to think about.
If you have well defined values, for example some function from states (or histories) of the universe to real numbers, such that larger numbers represent universe states that you would always prefer over smaller numbers, then every “should I do X or Y” question has an answer in terms of those values. In practice we’ll never have that, but still it’s worth thinking separately about “What are the expected consequences of the proposed policy?” and “What consequences do I want”, which a ‘should’ question implicitly mixes together.
You raise an excellent point! In hindsight I’m realizing that I should have chosen a different example, but I’ll stick with it for now. Yes, I agree that “What states of the universe are likely to result from me killing vs not killing lanternflies” and “Which states of the universe do I prefer?” are both questions grounded in the state of the universe where Bayes’ rule applies very well. However, I feel like there’s a third question floating around in the background: “Which states of the universe ‘should’ I prefer?” Based on my inner experiences, I feel that I can change my values at will. I specifically remember a moment after high school when I first formalized an objective function over states of the world, and this was a conscious thing I had to do. It didn’t come by default. You could argue that the question “Which states of the universe would I decide I should prefer after thinking about it for 10 years” is a question that’s grounded in the state of the universe so that Bayes’ Rule makes sense. However, trying to answer this question basically reduces to thinking about my values for 10 years; I don’t know of a way to short circuit that computation. I’m reminded of the problem about how an agent can reason about a world that it’s embedded inside where its thought processes could change the answers it seeks.
If I may propose another example and take this conversation to the meta-level, consider the question “Can Bayes’ Rule alone answer the question ‘Should I kill lanternflies?’?” When I think about this meta-question, I think you need a little more than just Bayes’ Rule to reason. You could start by trying to estimate P(Bayes Rule alone solves the lanternfly question), P(Bayes Rule alone solves the lanternfly question | the lanternfly question can be decomposed into two separate questions), etc. The problem is that I don’t see how to ground these probabilities in the real world. How can you go outside and collect data and arrive at the conclusion “P(Bayes Rule alone solves the lanternfly question | the lanternfly question can be decomposed into two separate questions) = 0.734”?
In fact, that’s basically the issue that my post is trying to address! I love Bayes’ rule! I love it so much that the punchline of my post, the dismissive growth-consistent ideology weighting, is my attempt to throw probability theory at abstract arguments that really didn’t ask for probability theory to be thrown at them. “Growth-consistency” is a fancy word I made up that basically means “you can apply probability theory (including Bayes’ Rule) in the way you expect.” I want to be able to reason with probability theory in places where we don’t get “real probabilities” inherited from the world around us.