Understanding Iterated Distillation and Amplification: Claims and Oversight

byWilliam_S10mo17th Apr 201822 comments


[Background: Intended for an audience that has some familiarity with Paul Christiano’s approach to AI Alignment. Understanding Iterated Distillation and Amplification should provide sufficient background.]

[Disclaimer: When I talk about “what Paul claims”, I am only summarizing what I think he means through reading his blog and participating on discussions on his posts. I could be mistaken/misleading in these claims]

I’ve recently updated my mental model of how Paul Christiano’s approach to AI alignment works, based on recent blog posts and discussions around them (in which I found Wei Dai’s comments particularly useful). I think that the update that I made might be easy to miss if you haven’t read the right posts/comments, so I think it’s useful to lay it out here. I cover two parts: understanding the limits on what Paul’s approach claims to accomplish, and understanding the role of the overseer in Paul’s approach. These considerations are important to understand if you’re trying to evaluate how likely this approach is to work, or trying to make technical progress on it.

What does Paul’s approach claim to accomplish?

First, it’s important to understand that what “Paul’s approach to AI alignment” claims to accomplish if it were carried out. The term “approach to AI alignment” can sound like it means “recipe for building a superintelligence that safely solves all of your problems”, but this is not how Paul intends to use this term. Paul goes into this in more detail in Clarifying “AI alignment”.

A rough summary is that his approach will only build an agent that is as capable as some known unaligned machine learning algorithm.

He does not claim that the end result of his approach is an agent that:

  • Can directly solve all problems which can be solved by a human
  • Will never take an unsafe catastrophic action
  • Will never take an action based on a misunderstanding your commands or your values
  • Could safely design successor agents or self-improve
  • Will have higher capability than an unaligned competitor

It’s important to understand the limits of what Paul’s approach claims in order to understand what it would accomplish, and the strategic situation that would result.

What is the Overseer?

Iterated Distillation and Amplification (IDA) describes a procedure that tries to take an overseer and produce an agent that does what the overseer would want it to do, with a reasonable amount of training overhead. “what the overseer would want it to do” is defined by repeating the amplification procedure. The post refers to amplification as the overseer using a number of machine learned assistants to solve problems. We can bound what IDA could accomplish by thinking about what the overseer could do if it could delegate to a number of copies of itself to solve problems (for a human overseer, this corresponds to HCH). To understand what this approach can accomplish, it’s important to understand what the overseer is doing. I think there are two different models of the overseer that could be inferred from different parts of the discussion around Paul’s work, which I label high bandwidth oversight and low bandwidth oversight.

High Bandwidth Overseer

The impression that I get from many of Paul’s posts is that the overseer is:

A high bandwidth overseer is a human that takes in an input and has some amount of time (between 15 minutes and a day) to process it. The human can look at as much of the input as it can within the allowed time, and when it delegates a sub-task it can look at the results. The main requirement for a human acting as an overseer is that they are trying to be helpful. The overseer can take in arbitrary natural-language requests and attempt to fulfill them.

The main question that comes to mind considering this model of the overseer is the problem of competent task decomposition:

Can we break down tasks into reasonably sized pieces (ie. can you solve a math problem from a textbook in 15 minutes by delegating to a number of people who don’t understand the material and only have 15 minutes each to interact with the textbook)?

This high bandwidth oversight model can be easier to use when trying to get a rough idea of how oversight works in order to understand how IDA works as a whole.

Low Bandwidth Overseer

However, looking at Universality and Security Amplification I found a different picture of what the overseer looks like:

A low bandwidth overseer is only allowed to process inputs from a finite input set. This includes both the original input query, and the results of subqueries. The overseer can pass information about the input or from a subquery to other copies of itself without looking at them.

To give a sense for the size of the input set, in Universality and Security Amplification, Paul speculates that input sets of size 10⁸ would probably be safe and inputs sets of size 10³⁰ would probably be unsafe.

To give a sense of what this implies, the range of input size 10⁸ to 10³⁰ roughly corresponds to:

  • 6 to 24 pixels of arbitrary 4-bit greyscale images
  • 10 to 38 words from typical english text
  • arbitrary phrases of 2 to 7 words from a vocabulary of 10000 words
  • arbitrary strings of 5 to 20 lowercase alphabetic characters

A source of potential confusion is that Paul still talks about a human fulfilling the role of the low bandwidth overseer (there are reasons for this that I won’t cover here). But when the space of information the human overseer can consider is reduced to a finite set, we could simply evaluate what the human does on every element in that set and produce a lookup table that replaces the human. In other words, if you don’t think that some task could be accomplished by an amplified lookup table as overseer, then you shouldn’t think it could be accomplished with a low bandwidth overseer.

The reason for this system being introduced is wanting to avoid security issues as the system scales. The fear is that there would be an “attack” on the system: an input that could be shown to an overseer that would cause the overseer to become corrupted and try to sabotage the system. This could be some kind of misleading philosophical argument, some form of blackmail, a human adversarial example, etc. If an input like this exists, then as soon as the first agent is corrupted, it can try to spread the attack to other agents. The first agent could be corrupted either by chance, or through an attack being included in the input. Paul’s proposal in Universality and Security Amplification is to avoid this by limiting the set of inputs that the overseer can process, and then use various techniques to verify that the overseer is not attackable on that set of inputs. I read this as implying that he thinks that a high bandwidth overseer will be sufficiently vulnerable to attack that after some number of rounds of amplification, the overseer would be likely to become misaligned.

How does a low bandwidth overseer impact the difficult of IDA?

Previously, I was mostly starting with the model of a high bandwidth overseer when thinking about IDA. I now think that Paul’s approach is intended to be using low bandwidth oversight, and that reasoning about the difficulty of the approach requires using this model.

Using a low bandwidth overseer more clearly requires solving a set of hard problems prior to using IDA at all:

  • Figure out how to decompose tasks into low-bandwidth pieces. The task decomposition needs to be both corrigible and capable.
    • Corrigibility requires understanding of AI safety concepts. For example, breaking down the task “What action does the user want me to take?” into the two subtasks “What are the user’s values?” and “What action is best according to these values”? is not corrigible. It produces an action optimised for some approximate model of the user’s values, which could be misaligned.
    • Capability requires having the ability to complete “enough” tasks. Paul acknowledges that the overseer will no longer be able to directly perform some tasks as well as a human (ie. they won’t be able to translate sentences as well if they only are able to look at small pieces of the original text). But in this case, he claims that it would be okay to understand how to safely use information provided by external resources (ie. human translators).
  • Clarifying the currently imprecise definition of “corrigibility” in order to be able to reason about whether a given task decomposition is corrigible.
  • Sufficiently understand meta-philosophy to implement it explicitly using collaborations of “lookup table overseers”. Even if we have an overseer that is corrigible and capable of performing well understood and defined tasks, it’s not clear that if we ask it to start evaluating tricky philosophical questions it will come up with aligned answers. This roughly looks like figuring out an intractably large algorithm that will output the products of MIRI’s Highly Reliable Agent Design research (ie. produce a set of criteria for what makes a good decision theory, a search space of possible decision theories, a prior over that space).

When considering the high bandwidth oversight regime, these problems seem more like they could be (at least partially) delegated to high bandwidth overseer at runtime. For example, one could think of preparing a summary of the relevant factors of a decision and giving it to a highly competent human overseer. The human overseer might be able to make good enough decisions without having an explicit model of decision theory (especially if odd edge cases don’t come up in practice).

Evaluating IDA

There are a number of lines of reasoning that one could use to try to get a sense of whether IDA could work, or how it should be prioritized relative to other approaches. Here, I summarize some of these considerations and indicate which versions of oversight they apply to, as I think this is important to be clear about. I don’t make claims about how these should be weighed, or claim to be exhaustive (there are additional considerations that would weigh on both forms of oversight, or other parts of IDA).

Evaluating High Bandwidth Oversight

Positive Considerations

  • Reasons for general optimism about “learning to reason from humans”, such as those that Daniel Dewey discusses in his thoughts on MIRI's "highly reliable agent design" work. For example, the individual overseers are acting like humans. This would lead the system to consider problems in the way that humans would, incorporating common sense about human motivations, coming up with solutions that are easier for humans to understand and less likely to contain weird surprises, and operating on inputs that are understandable.
  • If it seems like high bandwidth task decomposition could solve difficult problems (which is the question that Ought is running experiments to investigate)
  • IDA with high bandwidth oversight seems like some version of it could be implemented today
  • High bandwidth oversight seems that it could be implemented without solving many of the hard philosophical/mathematical problems that are faced by HRAD (decision theory, induction, etc.), instead substituting them for difficult machine learning problems.

Negative Consideration: Not Scalable and Secure

In high bandwidth oversight, if one copy of the overseer is corrupted, this corruption could easily spread. As more copies of the overseer are used to solve a problem, there is a higher chance of one copy becoming corrupted. Or an adversary could introduce a corrupting input into the system.

Evaluating Low Bandwidth Oversight

Positive Considerations

  • Paul’s intuitions suggest that it is possible to work with low bandwidth oversight, and he has discussed some aspects of how various problems might be handled.
  • If it seems plausible that meta-philosophy might be easier than object level philosophy - ie. defining an algorithm that we can’t run directly but outputs the correct decision theory might be easier than specifying the correct decision theory directly.
  • Paul claims that this approach will scale with increasing capability for any distillation algorithm.

Negative Consideration: No longer “learning to reason from humans”

I think that IDA with a low bandwidth overseer is not accurately described as “AI learns to reason from humans”, rather more “Humans figure out how to reason explicitly, then the AI learns from the explicit reasoning”. As Wei Dai has pointed out, amplified low bandwidth oversight will not actually end up reasoning like a human. Humans have implicit knowledge that helps them perform tasks when they see the whole task. But not all of this knowledge can be understood and break into smaller pieces. Low bandwidth oversight requires that the overseer not use any of this knowledge.

Now, it’s quite possible that performance still could be recovered by doing things like searching over a solution space, or by reasoning about when it is safe to use training data from insecure humans. But these solutions could look quite different from human reasoning. In discussion on Universality Amplification, Paul describes why he thinks that a low bandwidth overseer could still perform image classification, but the process looks very different from a human using their visual system to interpret the image:

“I’ve now played three rounds of the following game (inspired by Geoffrey Irving who has been thinking about debate): two debaters try to convince a judge about the contents of an image, e.g. by saying “It’s a cat because it has pointy ears.” To justify these claims, they make still simpler claims, like “The left ears is approximately separated from the background by two lines that meet at a 60 degree angle.” And so on. Ultimately if the debaters disagree about the contents of a single pixel then the judge is allowed to look at that pixel. This seems to give you a tree to reduce high-level claims about the image to low-level claims (which can be followed in reverse by amplification to classify the image). I believe the honest debater can quite easily win this game, and that this pretty strongly suggests that amplification will be able to classify the image.”

Conclusion: Weighing Evidence for IDA

The important takeaway is that considering IDA requires clarifying whether you are considering IDA with high or low bandwidth oversight. Then, only count considerations that actually apply to that approach. I think there’s a way to misunderstand the approach where you mostly think about high bandwidth oversight and count the feeling like it’s somewhat understandable, feels plausible to you that it could work and that it avoids some hard problems. But if you then also count Paul’s opinion that it could work, you may be overconfident - the approach that Paul claims is most likely to work is the low bandwidth oversight approach.

Additionally, I think it’s useful to consider both models as alternative tools for understanding oversight: for example, the problems in low bandwidth oversight might be less obvious but still important to consider in the high bandwidth oversight regime.

After understanding this, I am more nervous about whether Paul’s approach would work if implemented, due to the additional complications of working with low bandwidth oversight. I am somewhat optimistic that further work (such as fleshing out how particular problems could be address through low bandwidth oversight) will shed light on this issue, and either make it seem more likely to succeed or yield more understanding of why it won’t succeed. I’m also still optimistic about Paul’s approach yielding ideas or insights that could be useful for designing aligned AIs in different ways.

Caveat: high bandwidth oversight could still be useful to work on

High bandwidth oversight could still be useful to work on for the following reasons:

  • If you think that other solutions could be found to the security problem in high bandwidth oversight. Paul claims that low bandwidth oversight is the most likely solution to security issues within the overseer, but he thinks it may be possible to make IDA with high bandwidth oversight secure using various techniques for optimizing worst-case performance on the final distilled agent, even if the overseer is insecure. (see https://ai-alignment.com/two-guarantees-c4c03a6b434f)
  • It could help make progress on low bandwidth oversight. If high bandwidth oversight fails, then so will low bandwidth oversight. If high bandwidth oversight succeeds, then we might be able to break down each of the subtasks into low bandwidth tasks, directly yielding a low bandwidth overseer). I think the factored cognition experiments planned by Ought plausibly fall into this category.
  • If you think it could be used as a medium-term alignment solution or a fallback plan if no other alignment approach is ready in time. This seems like it would only work if it is used for limited tasks and a limited amount of time, in order to extend the time window for preparing a truly scalable approach. In this scenario, it would be very useful to have techniques that could help us understand how far the approach could be scaled before failure.