What are we assuming about utility functions?

by Grue_Slinky 1mo2nd Oct 20192 min read11 comments

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I often notice that in many (not all) discussions about utility functions, one side is "for" their relevance, while others tend to be "against" their usefulness, without explicitly saying what they mean. I don't think this is causing any deep confusions among researchers here, but I'd still like to take a stab at disambiguating some of this, if nothing else for my own sake. Here are some distinct (albeit related) ways that utility functions can come up in AI safety, in terms of what assumptions/hypotheses they give rise to:

AGI utility hypothesis: The first AGI will behave as if it is maximizing some utility function

ASI utility hypothesis: As AI capabilities improve well beyond human-level, it will behave more and more as if it is maximizing some utility function (or will have already reached that ideal earlier and stayed there)

Human utility hypothesis: Even though in some experimental contexts humans seem to not even be particularly goal-directed, utility functions are often a useful model of human preferences to use in AI safety research

Coherent Extrapolated Volition (CEV) hypothesis: For a given human H, there exists some utility function V such that if H is given the appropriate time/resources for reflection, H's values would converge to V

Some points to be made:

  • The "Goals vs Utility Functions" chapter of Rohin's Value Learning sequence, and the resulting discussion focused on differing intuitions about the AGI and ASI utility hypotheses (more accurately, as the title implies, the discussion was whether those agents will be broadly goal-directed at all, a weaker condition than being a utility maximizer).
  • AGI utility doesn't logically imply ASI utility, but I'd be surprised if anyone thinks it's very plausible for the former to be true while the latter fails. In particular, the coherence arguments and other pressures that move agents toward VNM seem to roughly scale with capabilities. A plausible stance could be that we should expect most ASIs to hew close to the VNM ideal, but these pressures aren't quite so overwhelming at the AGI level; in particular, humans are fairly goal-directed but only "partially" VNM, so the goal-directedness pressures on an AGI will likely be at this order of magnitude. Depending on takeoff speeds, we might get many years to try aligning AGIs at this level of goal-directedness, which seems less dangerous than playing sorcerer's apprentice with VNM-based AGIs at the same level of capability.(Note: I might be reifying VNM here too much, in thinking of things having a measure of "goal-directedness" with "very goal-directed" approximating VNM. But this basic picture could be wrong in all sorts of ways.)
  • The human utility hypothesis is much more vague than the others, and seems ultimately context-dependent. To my knowledge, the main argument in its favor is the fact that most of economics is founded on it. On the other hand, behavioral economists have formulated models like prospect theory for when greater precision is required than the simplistic VNM model gives, not to mention the cases where it breaks down more drastically. I haven't seen prospect theory used in AI safety research; I'm not sure if this reflects more a) the size of the field and the fact that few researchers have had much need to explicitly model human preferences, or b) that we don't need to model humans more than superficially. since this kind of research is still at a very early theoretical stage with all sorts of real-world error terms abounding.
  • The CEV hypothesis can be strengthened, consistent with Yudkowsky's original vision, to say that every human will converge to about the same values. But the extra "values converge" assumption seems orthogonal to one's opinions about the relevance of utility functions, so I'm not including it in the above list.
  • In practice a given researcher's opinions on these tend to be correlated, so it makes sense to talk of "pro-utility" and "anti-utility" viewpoints. But I'd guess the correlation is far from perfect, and at any rate, the arguments connecting these hypotheses seem somewhat tenuous.

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