Thanks for the engagement!
I think you’re mistaking Bayesian epistemology with Bayesian mathematics. Of course, no one denies Bayes’ theorem. The question is: to what should it be applied? Bayesian epistemology holds that rationality consists in updating your beliefs in accordance with Bayes’ theorem. As this LW post puts it:
Core tenet 3: We can use the concept of probability to measure our subjective belief in something. Furthermore, we can apply the mathematical laws regarding probability to choosing between different beliefs. If we want our beliefs to be correct, we must do so.
Next, it’s not that “Bayesianism is the right approach in these fields,” (I’m not sure what that means) it’s that Bayesian methods are useful for some problems. But Bayesianism falls short when it comes to explaining how we actually create knowledge. (No amount of updating on evidence + Newtonian mechanics gives you relativity.)
Despite his popularity among scientists who get given one philosophy of science class.
Love the ad hominem attack.
If you deny that observations confirm scientific theories, then you would have no reason to believe scientific theories which are supported by observational evidence, such as that smoking causes lung cancer.
Smoking causes lung cancer is a hypothesis, smoking does not cause lung cancer is another. We then discriminate between the hypotheses based on evidence (we falsify incorrect hypotheses). We slowly develop more and more sophisticated explanatory theories of how smoking causes lung cancer, always seeking to falsify them. At any time, we are left with the best explanation of a given phenomenon. This is how falsification works. (I can’t comment on your claim about Popper’s beliefs—but I would be surprised if true. His books are filled with examples of scientific progress.)
If you deny the rationality of induction, then you must be sceptical about all scientific theories that purport to be confirmed by observational evidence.
Yes. Theories are not confirmed by evidence (there’s no number of white swans you can see which confirms that all swans are white. “Swans are white” is a hypothesis, which can be refuted by seeing a black swan), they are falsified by it. Evidence plays the role of discrimination, not confirmation.
Inductive sceptics must hold that if you jumped out of a tenth floor balcony, you would be just as likely to float upwards as fall downwards.
No—because we have explanatory theories telling us why we’ll fall downwards (general relativity). These theories are the only ones which have survived scrutiny, which is why we abide by them. Confirmationism, on the other hand, purports to explain phenomenon by appealing to previous evidence. “Why do we fall downwards? Because we fell downwards before”. The sun rising tomorrow morning does not confirm the hypothesis that the sun rises every day. We should not increase our confidence in the sun rising tomorrow because it rose yesterday. Instead, we have a theory about why and when the sun rises when it does (heliocentric model + axis-tilt theory).
Observing additional evidence in favour of the theory should not increase our “credence” in it. Finding confirming evidence of a theory is easy, as evidenced by astrology and ghost stories. The amount of confirmatory evidence for these theories is irrelevant, what matters is whether and by what they can be falsified. There are more accounts of people seeing UFOs than there are of people witnessing gamma ray bursts. According the confirmationism, we should thus increase our credence in the former, and have almost none in the existence of the latter.
If you haven’t read this piece on the failure of probabilistic induction to favour one generalization over another, I highly encourage you to do so.
Anyway, happy to continue this debate if you’d like, but that was my primer.
Hi Owen! Really appreciate you engaging with this post. (In the interest of full disclosure, I should say that I’m the Ben acknowledged in the piece, and I’m in no way unbiased. Also, unrelatedly, your story of switching from pure maths to EA-related areas has had a big influence over my current trajectory, so thank you for that :) )
I’m confused about the claim
This seems in direct opposition to what the authors say (and what Vaden quoted above), namely that:
I understand that they may not feel this way, but it is what they argued for and is, consequently, the idea that deserves to be criticized. Next, you write that if
I don’t think so. The “immeasurability” of the future that Vaden has highlighted has nothing to do with the literal finiteness of the timeline of the universe. It has to do, rather, with the set of all possible futures (which is provably infinite). This set is immeasurable in the mathematical sense of lacking sufficient structure to be operated upon with a well-defined probability measure. Let me turn the question around on you: Suppose we knew that the time-horizon of the universe was finite, can you write out the sample space, $\sigma$-algebra, and measure which allows us to compute over possible futures?
Finally, I’m not sure what to make of
When reading their paper, I honestly did not read it as a toy example. And I don’t believe the authors state it as such. When discussing Shivani’s options they write:
and when discussing AI risk in particular:
Considering that the Open Philanthropy Project has poured millions into AI Safety, that it’s listed as a top cause by 80K, and that EA’s far-future-fund makes payouts to AI safety work, if Shivani’s reasoning isn’t to be taken seriously then now is probably a good time to make that abundantly clear. Apologies for the harshness in tone here, but for an august institute like GPI to make normative suggestions in its research and then expect no one to act on them is irresponsible.
Anyway, I’m a huge fan of 95% of EA’s work, but really think it has gone down the wrong path with longtermism. Sorry for the sass—much love to all :)