Towards a mechanistic understanding of corrigibility

by evhub 1mo22nd Aug 20194 comments

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Crossposted from the AI Alignment Forum. May contain more technical jargon than usual.

Acceptability

To be able to use something like relaxed adversarial training to verify a model, a necessary condition is having a good notion of acceptability. Paul Christiano describes the following two desiderata for any notion of acceptability:

  1. "As long as the model always behaves acceptably, and achieves a high reward on average, we can be happy."
  2. "Requiring a model to always behave acceptably wouldn't make a hard problem too much harder."

While these are good conditions that any notion of acceptability must satisfy, there may be many different possible acceptability predicates that meet both of these conditions—how do we distinguish between them? Two additional major conditions that I use for evaluating different acceptability criteria are as follows:

  1. It must be not that hard for an amplified overseer to verify that a model is acceptable.
  2. It must be not that hard to find such an acceptable model during training.

These conditions are different than Paul's second condition in that they are statements about the ease of training an acceptable model rather than the ease of choosing an acceptable action. If you want to be able to do some form of informed oversight to produce an acceptable model, however, these are some of the most important conditions to pay attention to. Thus, I generally think about choosing an acceptability condition as trying to answer the question: what is the easiest-to-train-and-verify property such that all models that satisfy that property[1] (and achieve high average reward) are safe?

Act-Based Corrigibility

One possible candidate property that Paul has proposed is act-based corrigibility, wherein an agent respects our short-term preferences, including those over how the agent itself should be modified. Not only is such an agent corrigible, Paul argues, but it will also want to make itself more corrigible, since having it be more corrigible is a component of our short-term preferences (Paul calls this the "broad basin" of corrigibility). While such act-based corrigibility would definitely be a nice property to have, it's unclear how exactly an amplified overseer could go about verifying such a property. In particular, if we want to verify such a property, we need a mechanistic understanding of act-based corrigibility rather than a behavioral one, since behavioral properties can only be verified by testing every input, whereas mechanistic properties can be verified just by inspecting the model.

One possible mechanistic understanding of corrigibility is corrigible alignment as described in "Risks from Learned Optimization," which is defined as the situation in which "the base objective is incorporated into the mesa-optimizer's epistemic model and [the mesa-optimizer's] objective is modified to 'point to' that information." While this gives us a starting point for understanding what a corrigible model might actually look like, there are still a bunch of missing pieces that have to be filled in. Furthermore, this notion of corrigibility looks more like instrumental corrigibility rather than act-based corrigibility, which as Paul notes is significantly less likely to be robust. Mechanistically, we can think of this lack of robustness as coming from the fact that "pointing" to the base objective is a pretty unstable operation: if you point even a little bit incorrectly, you'll end up with some sort of corrigible pseudo-alignment rather than corrigible robust alignment.

We can make this model more act-based, and at least somewhat mitigate this robustness problem, however, if we imagine pointing to only the human's short-term preferences. The hope for this sort of a setup is that, as long as the initial pointer is "good enough," there will be pressure for the mesa-optimizer to make its pointer better in the way in which its current understanding of short-term human preferences recommends, which is exactly Paul's "broad basin" of corrigibility argument. This requires it to be not that hard, however, to find a model with a notion of the human's short-term preferences as opposed to their long-term preferences that is also willing to correct that notion based on feedback.

In particular, it needs to be the case that it is not that hard to find an agent which will correct mistakes in its own prior over what the human's short-term preferences are. From a naive Bayesian perspective, this seems unlikely, as it seems strange for an agent to be incentivized to change its own prior. However, this is actually a very natural state for an agent to be in: if I trust your beliefs about X more than I trust my own, then that means I would endorse a modification of my prior to match yours. In the context of act-based corrigibility, we can think about this from a mechanistic perspective as having a pre-prior that encodes a belief that the human prior over human short-term preferences is to be preferred. Furthermore, pre-priors are generally epistemically valuable for agents to have, as a pre-prior can encourage an agent to correct its own cognitive biases. Thus, agents with pre-priors should be incentivized by most training processes, and thus shouldn't be too difficult to find.

Indifference Corrigibility

Instrumental and act-based corrigibility are not the only forms of corrigibility that have been discussed in the literature, however: there's also indifference corrigibility, wherein the agent is indifferent to modifications the human might make to it such as shutting it off. While this form of corrigibility doesn't in and of itself guarantee acceptability, if you had a way of verifying indifference corrigibility, there might be ways to turn that back into act-based corrigibility.

First, however, if we want to be able to verify indifference corrigibility, we are going to need a mechanistic understanding of it. Let's suppose we accept the argument that a competitive model will likely be a mesa-optimizer such that it will be running some sort of optimization process coupled with some sort of mesa-objective. Furthermore, let's suppose that its optimization process is computed over some sort of world model, which I think is a reasonable assumption for any competitive mesa-optimizer that wants to be able to take actions in the world. In such a case, we can think of indifference corrigibility as a form of stop gradient in the mesa-optimizer's world model which its optimization process doesn't optimize through,[2] which is a highly mechanistic property that we might expect an amplified overseer to be able to verify.

Again, however, we need agents with stop gradients to form a natural enough class such that they are not that hard to find. While it might naively seem as if agents with stop gradients would be very rare, in fact the exact opposite might be the case. Consider an agent such as the mesa-optimizer described previously which is running an optimization process over some world model, but which has preferences over the state of the world rather than the state of its world model. Such an agent will have an incentive to keep its world model aligned with the world, but only in one direction: it will want to modify its world model to match the world, but not modify the world to match its world model. This is a type of stop gradient, as it is a restriction on the agent to only minimize the difference between its world model and the world through one pathway but not through another. This example seems to suggest that stop gradients aren't that uncommon among agents such that it might be fairly achievable to find such an agent.

Even if we can train and verify indifference corrigibility, however, one of the big remaining problems with such an approach is that an indifference corrigible mesa-optimizer might do search in such a way that it finds a policy which is not itself indifference corrigible. We can think about this problem as arising from the fact that indifference corrigibility doesn't tile, though I more often think of this problem as the problem of "forwarding the guarantee," wherein even if we know how to do safe search on the outside, we have to make sure that any search inside of our model is similarly safe as well. This is a particularly interesting type of inner alignment problem in that, rather than being about how to ensure that a mesa-optimizer's objective is aligned, it is about how to ensure that a mesa-optimizer's search is safe even given that its objective is aligned. However, it seems plausible that this sort of problem could be resolved by ensuring that the model has a meta-preference towards any policies it produces also respecting the same stop gradient. In particular, the overseer could verify that any search over policies done by the model enforce the constraint that every policy have such a stop gradient.

Even once we can verify that our model is indifference corrigible and that it will forward that guarantee to any other search it might perform, however, there is still the question of how we might be able to use such a mechanism to produce a safe system. One way in which indifference corrigibility could be used to produce safety is to enforce that our model behave myopically. We can think of a myopic agent as one that only considers how best to answer the single question that you give to it rather than considering any sort of long-term consequences, which can be implemented as a stop gradient preventing any optimization outside of that domain. While myopia on its own is still insufficient to guarantee acceptability, it seems like it would at least prevent deceptive alignment, as one of the conditions for deceptive alignment is that the mesa-optimizer must have something to gain from cooperating now and then defecting later, which is not true for a myopic agent. Thus, if directed at a task which we are confident is outer aligned, such as pure supervised amplification (training a model to approximate a human consulting that model), and combined with a scheme for preventing standard pseudo-alignment (such as adversarial training), myopia verification might be sufficient to resolve the rest of the inner alignment problem by preventing deceptive alignment.

Conclusion

If we want to be able to do relaxed adversarial training to produce safe AI systems, we are going to need a notion of acceptability which is not that hard to train and verify. Corrigibility seems to be one of the most promising candidates for such an acceptability condition, but for that to work we need a mechanistic understanding of exactly what sort of corrigibility we're shooting for and how it will ensure safety. I think that both of the paths considered here—both act-based corrigibility and indifference corrigibility—look like promising research directions for attacking this problem.


  1. Or at least all models that we can find that satisfy that property. ↩︎

  2. Thanks to Scott Garrabrant for the stop gradient analogy. ↩︎

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