Jan Leike is a senior research scientist who leads the agent alignment team at DeepMind. His is one of three teams within their technical AGI group; each team focuses on different aspects of ensuring advanced AI systems are aligned and beneficial. Jan’s journey in the field of AI has taken him from a PhD on a theoretical reinforcement learning agent called AIXI to empirical AI safety research focused on recursive reward modeling. This conversation explores his movement from theoretical to empirical AI safety research — why empirical safety research is important and how this has lead him to his work on recursive reward modeling. We also discuss research directions he’s optimistic will lead to safely scalable systems, more facets of his own thinking, and other work being done at DeepMind.
Topics discussed in this episode include:
- Theoretical and empirical AI safety research
- Jan’s and DeepMind’s approaches to AI safety
- Jan’s work and thoughts on recursive reward modeling
- AI safety benchmarking at DeepMind
- The potential modularity of AGI
- Comments on the cultural and intellectual differences between the AI safety and mainstream AI communities
- Joining the DeepMind safety team
2:15 Jan’s intellectual journey in computer science to AI safety
7:35 Transitioning from theoretical to empirical research
11:25 Jan’s and DeepMind’s approach to AI safety
17:23 Recursive reward modeling
29:26 Experimenting with recursive reward modeling
32:42 How recursive reward modeling serves AI safety
34:55 Pessimism about recursive reward modeling
38:35 How this research direction fits in the safety landscape
42:10 Can deep reinforcement learning get us to AGI?
42:50 How modular will AGI be?
44:25 Efforts at DeepMind for AI safety benchmarking
49:30 Differences between the AI safety and mainstream AI communities
55:15 Most exciting piece of empirical safety work in the next 5 years
56:35 Joining the DeepMind safety team
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Lucas Perry: Hello everyone and welcome to the AI Alignment Podcast. I’m Lucas Perry. Today, we’re speaking with Jan Leike. Jan Leike is a senior research scientist at DeepMind and his research aims at helping to make machine learning robust and beneficial; he works on safety and alignment of reinforcement learning agents. His current research can be understood as motivated by the following question: How can we design competitive and scalable machine learning algorithms that make sequential decisions in the absence of a reward function? If this podcast is interesting or valuable to you, please consider following us on your preferred listening platform and leaving us a good review.
This conversation covers Jan’s PhD and movement from theoretical to empirical AI research, why this shift took place and his view on the importance of empirical AI safety research, we discuss how DeepMind approaches the projects of beneficial AI and AI safety. We discuss the AI alignment landscape today and the kinds of approaches that Jan is most excited about. We get into Jan’s main area of research of recursive reward modeling, and we talk about AI safety benchmarking efforts at DeepMind and the intellectual and cultural differences between the AI alignment/AI safety community and the mainstream AI and machine learning community. As a friendly heads up, there were some audio issues with the incoming audio in the second half of the podcast. We did our best to clean these up and I feel the resulting audio to be easily listenable. I’d also like to give many thanks to Richard Ngo, Vishal Maini, and Richard Mallah for help on developing and refining the questions for this podcast. And with that, let’s get into our conversation with Jan Leike.
Why don’t you start off by taking us through your journey in the field of AI. How did you first become interested in math and computer science? Tell me a little bit about your time as a PhD student. What perked your curiosity where, why you were pursuing what you were pursuing?
Jan Leike: I got interested in AGI and AGI safety around 2012. I was doing a Master’s degree at a time, and I was trying to think about what I should do with my career. And I was reading a whole bunch of stuff online. That’s how I got into this whole area. My background was kind of in math and computer science at the time, but I wasn’t really working on AI. I was more working on software verification. Then I came across Marcus Hutter’s AIXI model, which is basically a formal mathematical model for what AGI could look like. And it’s highly idealized. It’s not something that could actually run, but you can kind of think about it and you can actually prove things about it. And I was really excited about that. I thought that was a great starting point because you remember that was back in 2012 before the whole deep learning revolution happened, so it was not really clear what kind of approaches might we actually take towards AGI. The purpose of my PhD was to kind of understand AGI from a high-level theoretical perspective.
Lucas Perry: The PhD was with Marcus Hutter on AIXI or “A,” “I,” “X,” “I.” From that pursuit, what interesting or really valuable things did you glean from that process?
Jan Leike: So my thesis ended up being just a number of theoretical results, some of which are that actually this idealized agent AIXI is not optimal in any objective sense. In a way, it all depends on the universal Turing machine that is used to define it. But however, there’s variants on AIXI that have objective properties, such as asymptotic convergence to the optimal policy. This variant is basically a variant based on Thompson sampling, but this is a fully general reinforcement learning setting. So that’s partially observable, and you don’t have episodes. It’s like everything is one long episode. So it’s not really a setting where you can give any sample complexity bounds. Asymptotic convergence is all you can do. And then another thing that came out of that was what we called, “A Formal Solution to the Grain of Truth Problem.” This is a collaboration with the Machine Intelligence Research Institute.
And the idea here is that one of the problems with the AIXI formal model is that it assumes that its environment is computable, but itself is incomputable. You can’t really do multi-agent analysis with it. And so what we did was propose a formalism that is like a variant on AIXI that can be in its own environment class if we embed an agent or environment together with other of these AIXI like agents. And then while they do that, they can still asymptotically learn to predict correctly what the agents will do and then converge to Nash equilibrium asymptotically.
Lucas Perry: So the sense in which AIXI was a theoretical ideal was that the process by which it was able to learn or infer preferences was computationally intractable.
Jan Leike: The AIXI model basically just tries to answer the reinforcement learning question. So you’re given an environment and you’re given a reward signal, how do you optimize that? In a way, you’re using what we call the Solomonoff prior to predict the next observations that come from the environment, and then you essentially do an exhaustive tree search over all the possible action sequences that you could take and the possible consequences that you would predict and then make the best action in terms of returns. This is kind of similar to how AlphaGo uses Monte Carlo tree search to select the best actions. The reason why you can’t literally build AIXI is that this Solomonoff prior that I mentioned, it is basically the set of all possible Turing machines which is countably infinite, and then you have to run all of them in parallel and take a weighted average over what they would predict.
If you’ve ever tried to run all of computer programs in parallel, you’ll know that this is not going to go too well. I find AIXI helpful when thinking about AGI in terms of what could advanced machine learning or reinforcement learning agents look like. So they have some kind of learned model in which they do planning and select actions that are good in the long run. So I think in a way it tells us that if you believe that the reinforcement learning problem is the right problem to phrase an AGI in, then AIXI proves that there can be a solution to that problem. I think on a high level, having thought about this model is useful when thinking about where are we headed and what are potential milestones on the way to AGI. But at the same time, I think my mistake at the time was really getting lost in some of the technical details that really matter if you want to publish a paper on this stuff, but don’t transfer as much in the analogy.
Lucas Perry: After you finished up your PhD with Hutter, you finished working on AIXI now. Is this when you transitioned to DeepMind and make this transition from theoretical to empirical research?
Jan Leike: Yeah, that’s basically right. At the time when I started my PhD, I decided to work on theory because it wasn’t really clear to me what AGI would look like and how we’d build it. So I wanted to do something general and something more timeless. Then we saw a whole bunch of evidence that deep reinforcement learning is viable and you can make it work. Came out with a DQN nature paper, and there was the AlphaGo event. And then it became pretty clear to me that deep reinforcement learning was going somewhere, and that’s something we should work on. At the time, my tool set was very theoretical and my comparative advantage was thinking about theory and using the tools that I learned and developed in my PhD.
And the problem was that deep reinforcement learning has very little theory behind it, and there’s very little theory on RL. And the little theory on RL that we have says that basically function approximation shouldn’t really work. So that means it’s really hard to actually gain traction on doing something theoretically. And at the same time, at the time we were very clear that we could just take some agents that existed and we can just build something, and then we could make incremental progress on things that would actually help us make AGI safer.
Lucas Perry: Can you clarify how the theoretical foundations of deep reinforcement learning are weak? What does that mean? Does that mean that we have this thing and it works, but we’re not super sure about how it works? Or the theories about the mechanisms which constitute that functioning thing are weak? We can’t extrapolate out very far with them?
Jan Leike: Yeah, so basically there’s the two parts. So if you take deep neural networks, there are some results that tell you that depth is better than width. And if you increase capacity, you can represent any function and things like that. But basically the kind of thing that I would want to use is real sample complexity bounds that tell you if your network has X many parameters, how much training data you do need, how many batches do you need to train in order to actually converge? Can you converge asymptotically? None of these things are even true in theory. You can get examples where it doesn’t work. And of course we know that in practice because sometimes training is just unstable, but it doesn’t mean that you can’t tune it and make it work in practice.
On the RL side, there is a bunch of convergence results that people have given in tabular MDPs, Markov decision processes. In that setting, everything is really nice and you can give sample complexity bounds, or let’s say some bounds on how long learning will take. But as soon as you kind of go into a function approximation setting, all bets are off and there’s very simple two-state MDPs they can draw where just simple linear function approximation completely breaks. And this is a problem that we haven’t really gotten a great handle on theoretically. And so going from linear function approximation to deep neural networks is just going to make everything so much harder.
Lucas Perry: Are there any other significant ways in which your thinking has changed as you transitioned from theoretical to empirical?
Jan Leike: In the absence of these theoretical tools, you have two options. Either you try to develop these tools, and that seems very hard and many smart people have tried for a long time. Or you just move on to different tools. And I think especially if you have systems that you can do experiments on, then having an empirical approach makes a lot of sense if you think that these systems actually can teach us something useful about the kind of systems that we are going to build in the future.
Lucas Perry: A lot of your thinking has been about understanding the theoretical foundations, like what AGI might even look like, and then transitioning to an empirical based approach that you see as efficacious for studying systems in the real world and bringing about safe AGI systems. So now that you’re in DeepMind and you’re in this intellectual journey that we’re covering, how is DeepMind and how is Jan approaching beneficial AI and AI alignment in this context?
Jan Leike: DeepMind is a big place, and there is a lot of different safety efforts across the organization. People are working on say robustness to adversarial inputs, fairness, verification of neural networks, interpretability and so on and so on. What I’m doing is I’m focusing on reward modeling as an approach to alignment.
Lucas Perry: So just taking a step back and still trying to get a bigger picture of DeepMind’s approach to beneficial AI and AI alignment. It’s being attacked at many different angles. So could you clarify this what seems to be like a portfolio approach? The AI alignment slash AI safety agendas that I’ve seen enumerate several different characteristics or areas of alignment and safety research that we need to get a grapple on, and it seems like DeepMind is trying its best to hit on all of them.
Jan Leike: DeepMind’s approach to safety is quite like a portfolio. We don’t really know what will end up panning out. So we pursue a bunch of different approaches in parallel. So I’m on the technical AGI safety team that roughly consists of three subteams. There’s a team around incentive theory that tries to model on a high level what incentives agents could have in different situations and how we could understand them. Then there is an agent analysis team that is trying to take some of our state of the art agents and figure out what they are doing and how they’re making the decisions they make. And this can be both from a behavioral perspective and from actually looking inside the neural networks. And then finally there is the agent alignment team, which I’m leading, and that’s trying to figure out how to scale reward modeling. There’s also an ethics research team, and then there’s a policy team.
Lucas Perry: This is a good place then to pivot into how you see the AI alignment landscape today. You guys have this portfolio approach that you just explained. Given that and given all of these various efforts for attacking the problem of beneficial AI from different directions, how do you see the AI alignment landscape today? Is there any more insight that you can provide into that portfolio approach given that it is contextualized within many other different organizations who are also coming at the problem from specific angles? So like MIRI is working on agent foundations and does theoretical research. CHAI has its own things that it’s interested in, like cooperative inverse reinforcement learning and inverse reinforcement learning. OpenAI is also doing its own thing that I’m less clear on, which may have to do with factored evaluation. Ought as well is working on stuff. So could you expand a little bit here on that?
Jan Leike: Our direction for getting a solution to the alignment problem revolves around recursive reward modeling. I think on a high level, basically the way I’m thinking about this is that if you’re working on alignment, you really want to be part of the projects that builds AGI. Be there and have impact while that happens. In order to do that, you kind of need to be a part of the action. So you really have to understand the tech on the detailed level. And I don’t think that safety is an add on that you think of later or then add at a later stage in the process. And I don’t think we can just do some theory work that informs algorithmic decisions that make everything go well. I think we need something that is a lot more integrated with the project that actually builds AGI. So in particular, the way we are currently thinking about is it seems like the part that actually gives you alignment is not this algorithmic change and more something like an overall training procedure on how to combine your machine learning components into a big system.
So in terms of how I pick my research directions, I am most excited about approaches that can scale to AGI and beyond. Another thing that I think is really important is that I think people will just want to build agents, and we can’t only constrain ourselves to building say question answering systems. There’s basically a lot of real world problems that we want to solve with AGI, and these are fundamentally sequential decision problems, right? So if I look something up online and then I write an email, there’s a sequence of decisions I make, which websites I access and which links I click on. And then there’s a sequence of decisions of which characters are input in the email. And if you phrase the problem as, “I want to be able to do most things that humans can do with a mouse and a keyboard on a computer,” then that’s a very clearly scoped reinforcement learning problem. Although the reward function problem is not very clear.
Lucas Perry: So you’re articulating that DeepMind, you would explain that even given all these different approaches you guys have on all these different safety teams, the way that you personally pick your research direction is that you’re excited about things which safely scale to AGI and superintelligence and beyond. And that recursive reward modeling is one of these things.
Jan Leike: Yeah. So the problem that we’re trying to solve is the agent alignment problem. And the agent alignment problem is the question of how can we create agents that act in accordance with the user’s intentions. We are kind of inherently focused around agents. But also, we’re trying to figure out how to get them to do what we want. So in terms of reinforcement learning, what we’re trying to do is learn a reward function that captures the user’s intentions and that we can optimize with RL.
Lucas Perry: So let’s get into your work here on recursive reward modeling. This is something that you’re personally working on. Let’s just start off with what is recursive reward modeling?
Jan Leike: I’m going to start off with explaining what reward modeling is. What we want to do is we want to apply reinforcement learning to the real world. And one of the fundamental problems of doing that is that the real world doesn’t have built in reward functions. And so basically what we need is a reward function that captures the user’s intentions. Let me give you an example for the core motivation of why we want to do reward modeling, a blog posts that OpenAI made a while back: The Boat Race Problem, where they were training a reinforcement modeling agent to race the boat around the track and complete the race as fast as possible, but what actually ended up happening is that the boat was getting stuck in the small lagoon and then circling around there. And the reason for that is the RL agent was trying to maximize the number of points that it gets.
And the way you get points in this game is by moving over these buoys that are along the track. And so if you go to the lagoon, there’s these buoys that keep respawning, and then so you can get a lot of points without actually completing the race. This is the kind of behavior that we don’t want out of our AI systems. But then on the other hand, there’s things we wouldn’t think of but we want out of our AI systems. And I think a good example is AlphaGo’s famous Move 37. In its Go game against Lee Sedol, Move 37 was this brilliant move that AlphaGo made that was a move that no human would have made, but it actually ended up turning around the entire game in AlphaGo’s favor. And this is how Lee Sedol ended up losing the game. The commonality between both of these examples is some AI system doing something that a human wouldn’t do.
In one case, that’s something that we want: Move 37. In the other case, it’s something that we don’t want, this is the circling boat. I think the crucial difference here is in what is the goal of the task. In the Go example, the goal was to win the game of Go. Whereas in the boat race example, the goal was to go around the track and complete the race, and the agent clearly wasn’t accomplishing that goal. So that’s why we want to be able to communicate goals to our agents. So we need these goals or these reward functions that our agents learn to be aligned with the user’s intentions. If we do it this way, we also get the possibility that our systems actually outperform humans and actually do something that would be better than what the human would have done. And this is something that you, for example, couldn’t get out of imitation learning or inverse reinforcement learning.
The central claim that reward modeling is revolving around is that evaluation is easier than behavior. So I can, for example, look at a video of an agent and tell you whether or not that agent is doing a backflip, even though I couldn’t do a backflip myself. So in this case, it’s kind of harder to actually do the task than to evaluate it. And that kind of puts the human in the leveraged position because the human only has to be able to give feedback on the behavior rather than actually being able to do it. So we’ve been building prototypes for reward modeling for a number of years now. We want to actually get hands on experience with these systems and see examples of where they fail and how we can fix them. One particular example seen again and again is if you don’t provide online feedback to the agent, something can happen is that the agent finds loopholes in the reward model.
It finds states where the reward model think it’s a high reward state, but actually it isn’t. So one example is in the Atari game Hero, where you can get points for shooting laser beams at spiders. And so what the agent figures out is that if it stands really close to the spider and starts shooting but then turns around and the shot goes the other way, then the reward model will think the shot is about to hit the spider so it should give you a reward because that gives you points. But actually the agent doesn’t end killing the spider, and so it can just do the same thing again and again and get reward for it.
And so it’s kind of found this exploit in the reward model. We know that online training, training with an actual human in the loop who keeps giving feedback, can get you around this problem. And the reason is that whenever the agent gets stuck in these kinds of loopholes, a human can just look at the agent’s behavior and give some additional feedback you can then use to update the reward model. And the reward model in turn can then teach the agent that this is actually not a high reward state. So what about recursive reward modeling? One question that we have when you’re trying to think about how to scale reward modeling is that eventually you want to tackle domains where it’s too hard for the human to really figure out what’s going on because the core problem is very complex or the human is not an expert in the domain.
Right now, this is basically only in the idea stage, but the basic idea is to apply reward modeling recursively. You have this evaluation task that is too complex for the human to do, and you’re training a bunch of evaluation helper agents that will help you do the evaluation of the main agent that you’re training. These agents then in turn will be trained with reward modeling or recursive reward modeling.
Let’s say you want to train the agent that designs a computer chip, and so it does a bunch of work, and then it outputs this giant schema for what the chip could look like. Now that schema is so complex and so complicated that, as a human, even if you were an expert in chip design, you wouldn’t be able to understand all of that, but you can figure out what aspects of the chip you care about, right? Like what is the number of, say, FLOPS it can do per second or what is the thermal properties.
For each of these aspects that you care about, you will spin up another agent, you teach another agent how to do that subtask, and then you would use the output of that agent, could be, let’s say, a document that details the thermal properties or a benchmark result on how this chip would do if we actually built it. And then you can look at all of these outputs of the evaluation helper agents, and then you compose those into feedback for the actual agent that you’re training.
The idea is here that basically the tasks that the evaluation helper agents have to do are easier problems in a more narrow domain because, A, they only have to do one sub-aspect of the evaluation, and also you’re relying on the fact that evaluation is easier than behavior. Since you have this easier task, you would hope that if you can solve easier tasks, then you can use the solutions or the agents that you train on these easier tasks to kind of scaffold your way up to solving harder and harder tasks. You could use this to push out the general scope of tasks that you can tackle with your AI systems.
The hope would be that, at least I would claim, that this is a general scheme that, in principle, can capture a lot of human economic activity that way. One really crucial aspect is that you’re able to compose a training signal for the agents that are trying to solve the task. You have to ground this out where you’re in some level, if you picture this big tree or directed acyclic graph of agents that help you train other agents and so on, there has to be a bottom level where the human can just look at what’s going on and can just give feedback directly, and use the feedback on the lowest level task to build up more and more complex training signals for more and more complex agents that are solving harder and harder tasks.
Lucas Perry: Can you clarify how the bootstrapping here happens? Like the very bottom level, how you’re first able to train the agents dedicated to sub-questions of the larger question?
Jan Leike: If you give me a new task to solve with recursive reward modeling, the way I would proceed is, assuming that we solved all of these technical problems, let’s say we can train agents with reward modeling on arbitrary tasks, then the way I would solve it is I would first think about what do you care about in this task? How do I measure its success? What are the different aspects of success that I care about? These are going to be my evaluation criteria.
For each of my evaluation criteria, I’m going to define a new subtask, and the subtasks will be “help me evaluate this criteria.” In the computer chip example, that was FLOPs per second, and so on, and so on. Then I proceed recursively. For each of the subtasks that I just identified, I start again by saying, “Okay, so now I have this agent, it’s supposed to get computer chip design, and a bunch of associated documentation, say, and now it has to produce this document that outlines the thermal properties of this chip.”
What I would do, again, is I’d be like, “Okay, this is a pretty complex task, so let’s think about how to break it down. How would I evaluate this document?” So I proceed to do this until I arrive at a task where I can just say, “Okay, I basically know how to do this task, or I know how to evaluate this task.” And then I can start spinning up my agents, right? And then I train the agents on those tasks, and then once I’ve trained all of my agents on the leaf level tasks, and I’m happy with those, I then proceed training the next level higher.
Lucas Perry: And the evaluation criteria, or aspects, are an expression of your reward function, right?
Jan Leike: The reward function will end up capturing all of that. Let’s say we have solved all of the evaluation subtasks, right? We can use the evaluation assistant agents to help us evaluate the overall performance of the main agent that you were training. Of course, whenever this agent does something, you don’t want to have to evaluate all of their behavior, so what you do is you essentially distill this whole tree of different evaluation helper agents that you build. There’s lots of little humans in the loop in that tree into one model that will predict what that whole tree of what agents and humans will say. That will basically be the reward that the main agent is being trained on.
Lucas Perry: That’s pretty beautiful. I mean, the structure is elegant.
Jan Leike: Thanks.
Lucas Perry: I still don’t fully understand it obviously, but it’s beginning to dawn upon my non-computer science consciousness.
Jan Leike: Well, current research on this stuff revolves around two questions, and I think these are the main questions that we need to think about when trying to figure out whether or not a scheme like this can work. The first question is how well does the one-step set up work, only reward modeling, no recursion? If one-step reward modeling doesn’t work, you can’t hope to ever build a whole tree out of that component, so clearly that has to be true.
And then the second question is how do errors accumulate if we build a system? Essentially what you’re doing is you’re training a bunch of machine learning components to help you build a training signal for other machine learning components. Of course none of them are going to be perfect. Even if my ability to do machine learning is infinitely great, which of course it isn’t, at the end of the day, they’re still being trained by humans, and humans make mistakes every once in a while.
If my bottom level has a certain, let’s say, reward accuracy, the next level up that I use those to train is going to have a lower accuracy, or potentially have a lower accuracy, because their training signal is slightly off. Now, if you keep doing this and building a more and more complex system, how do the errors in the system accumulate? This is a question we haven’t really done much work on so far, and this is certainly something we need to do more on in the future.
Lucas Perry: What sorts of experiments can we do with recursive reward modeling today, and why is it hard?
Jan Leike: The reason why this is difficult to find such tasks is because essentially you need tasks that have two properties. The first property is they have to be difficult enough so that you can’t evaluate them directly, right? Otherwise, you wouldn’t need the recursive part in recursive reward modeling. And then secondly, they have to be easy enough that we can actually hope to be able to do them with today’s systems.
In a way, it’s two very contradictory objectives, so it’s kind of hard to find something in the intersection. We can study a lot of the crucial parts of this independently of actually being able to build a prototype of the recursive part of recursive reward modeling.
Lucas Perry: I guess I’m just trying to also get a sense of when you think that recursive reward modeling might become feasible.
Jan Leike: One good point would be where we could get to the point where we’ve done like a whole lot of tasks with reward modeling, and we’re basically running out of tasks that we can do directly. Or an opportunity comes up when we find a task that we actually think we can do and that requires a decomposition. There’s ways in which you could try to do this now by artificially limiting yourself. You could, for example, solve chess with recursive reward modeling by pretending that there isn’t a procedure or reward function for chess.
If you rely on the human to look at the board and tell you whether or not it’s checkmate, if you’re like a pro chess player, you could probably do that quite well. But if you’re an amateur or a non-expert, you don’t really know that much about chess other than the rules, it’s kind of hard for a human to do that quickly.
What you could do is you could train evaluation helper agents that give you useful information about the chessboard, where, let’s say, they color certain tiles on the board that are currently under threat. And then using that information, you can make the assessment of whether this is a checkmate situation much more easily.
While we could do this kind of setup and use recursive reward modeling, and you’ll maybe learn something, at the same time, it’s not an ideal test bed because it’s just not going to look impressive as a solution because we already know how to use machine learning to play chess, so we wouldn’t really add anything in terms of value of tasks that we can do now that we couldn’t do otherwise.
Lucas Perry: But wouldn’t it show you that recursive reward modeling works?
Jan Leike: You get one data point on this particular domain, and so the question is what data points would you learn about recursive reward modeling that you wouldn’t learn in other ways? You could treat this as like two different individual tasks that you just solve with reward modeling. One task is coloring the tiles of the board, and one task is actually playing chess. We know we can do the latter, because we’ve done that.
What would be interesting about this experiment would be that you kind of learn how to cope with the errors in the system. Every once in a while, like the human will label a state incorrectly, and so you would learn how well you can still train even though your training signal is slightly off. I think we can also investigate that without actually having to literally build this recursive setup. I think there’s easier experiments we could do.
Lucas Perry: Do you want to offer any final words of clarification or just something succinct about how this serves AI safety and alignment?
Jan Leike: One way to think about safety is this specification robustness assurance framework. What this is, is basically a very high-level way of carving the space of safety problems into different categories. These are three categories. The first category is specification. How do you get the system to do what you want? Basically, what we usually mean when we talk about alignment. The second category is robustness. How can you make your system robust to various perturbations, such as adversarial inputs or distributional changes? The third category is assurance. How can you get better calibrated beliefs about how safe, or in the sense of robust and specification too, your system actually is?
Usually in assurance category, we talk about various tools for understanding and monitoring agents, right? This is stuff about testing, interpretability, verification, and so on, and so on. The stuff that I am primarily working on is in the specification category, where we’re basically trying to figure out how to get our agents to pursue the goals that we want them to pursue. The ambition of recursive reward modeling is to solve all of the specification problems. Some of the problems that we worry about are, let’s say, off switch problems, where your agent might meddle with its off switch, and you just don’t want it to do that. Another problem, let’s say, what about side effects? What about reward tampering? There’s a whole class of these kind of problems, and instead of trying to solve them each individually, we try to solve the whole class of problems at once.
Lucas Perry: Yeah, it’s an ambitious project. The success of figuring out the specification problem supervenes upon other things, but at the same time, if those other things are figured out, the solution to this enables, as you’re saying, a system which safely scales to super intelligence and beyond, and retains alignment, right?
Jan Leike: That’s the claim.
Lucas Perry: Its position then in AI safety and alignment is pretty clear to me. I’m not sure if you have other points you want to add to that though?
Jan Leike: Nope, I think that was it.
Lucas Perry: Okay. We’re just going to hit on a few more questions here then on recursive reward modeling. Recursive reward modeling seems to require some very competent agent or person to break down an evaluation into sub-questions or sub-evaluations. Is the creation of that structure actually scalable?
Jan Leike: Yeah, this is a really good question. I would picture these decompositions of the evaluation task to be essentially hardcoded, so you have a human expert that knows something about the task, and they can tell you what they care about in the task. The way I picture this is you could probably do a lot of the tasks in recursion depth of three, or five, or something like that, but eventually they’re so out of the range of what the human can do that they don’t even know how to break down the evaluation of that task.
Then this decomposition problem is not a problem that you want to tackle with recursive reward modeling, where basically you train an agent to propose decompositions, and then you have an evaluation where the human evaluates whether or not that was good decomposition. This is very, very far future stuff at that point; you’ve already worked with recursive reward modeling for a while, and you have done a bunch of decompositions, and so I don’t expect this to be something that we will be addressing anytime soon, and it’s certainly something that is within the scope of what the stuff should be able to do.
Recursive reward modeling is a super general method that you basically want to be able to apply to any kind of task that humans typically do, and proposing decompositions of the evaluation is one of them.
Lucas Perry: Are there pessimisms that you have about recursive reward modeling? How might recursive reward modeling fall short? And I think the three areas that we want to hit here are robustness, mesa-optimizers, and tasks that are difficult to ground.
Jan Leike: As I said earlier, basically you’re trying to solve the whole class of specification problems, where you still need robustness and assurance. In particular, there’s what we call the reward to result gap, where you might have the right reward function, and then you still need to find an agent that actually is good at optimizing that reward function. That’s an obvious problem, and there’s a lot of people just trying to make RL agents perform better. Mesa-optimizers I think are, in general, an open question. There’s still a lot of uncertainty around how they would come up, and what exactly is going on there. I think one thing that would be really cool is actually have a demo of how they could come up in a training procedure in a way that people wouldn’t expect. I think that would be pretty valuable.
And then thirdly, recursive reward modeling is probably not very well suited for tasks that are really difficult to ground. Moral philosophy might be in that category. The way I understand this is that moral philosophy tries to tackle questions that is really difficult to get really hard facts and empirical evidence on. These human intuitions might be like really difficult to ground, and to actually teach to our agents in a way that generalizes. If you don’t have this grounding, then I don’t know how you could build a training signal for the higher level questions that might evolve from that.
In other words, to make this concrete, let’s say I want to train an agent to write a really good book in moral philosophy, and now of course I can evaluate that book based on how novel it is relative to what the humans have written, or like the general literature. How interesting is it? Does it make intuitive sense? But then in order to actually make the progress on moral philosophy, I need to update my value somehow in a way that is actually the right direction, and I don’t really know what would be a good way to evaluate.
Lucas Perry: I think then it would be a good spot here for us to circle back around to the alignment landscape. A lot of what you’ve been saying here has rung bells in my head about other efforts, like with iterated distillation and application, and debate with Geoffrey Irving, and factored evaluation at Ought. There’s these categories of things which are supposed to be general solutions to making systems which safely scale to aligned super intelligence and beyond. This also fits in that vein of the alignment landscape, right?
Jan Leike: Yeah. I think that’s right. In some ways, the stuff that you mentioned, like projects that people are pursuing at OpenAI, and at Ought, share lot structure with what recursive reward modeling is trying to do, where you try to compose training signals for tasks that are too hard for humans. I think one of the big differences in how we think about this problem is that we want to figure out how to train the agents that do stuff in the world, and I think a lot of the discussion at OpenAI and Ought kind of center around building question answering systems and fine tuning language models, where the ambition is to get them to do reasoning tasks that are very difficult for humans to do directly, and then you do that by decomposing them into easier reasoning tasks. You could say it’s one scalable alignment technique out of several that are being proposed, and we have a special focus on agents. I think agents are great. I think people will build agents that do stuff in the world, take sequential actions, look at videos.
Lucas Perry: What research directions or projects are you most excited about, just in general?
Jan Leike: In general, the safety community as a whole should have a portfolio approach where we just try to pursue a bunch of paths in parallel, essentially as many as can be pursued in parallel. I personally I’m most excited about approaches that can work with existing deep learning and scale to AGI and beyond. There could be many ways in which things pan out in the future, but right now there’s an enormous amount of resources being put towards scaling deep learning. That’s something that we should take seriously and consider into the way we think about solutions to the problem.
Lucas Perry: This also reflects your support and insistence on empirical practice as being beneficial, and the importance of being in and amongst the pragmatic, empirical, tangible, real-world, present-day projects, which are likely to bring about AGI, such that one can have an impact. What do you think is missing or underserved in AI alignment and AI safety? If you were given, say, like $1 billion, how would you invest it here?
Jan Leike: That would be the same answer I just gave you before. Basically, I think you want to have a portfolio, so you invest that money to like a whole bunch of directions. I think I would invest more than many other people in the community towards working empirically with, let’s say, today’s deep RL systems, build prototypes of aligned AGI, and then do experiments on them. I’ll be excited to see more of that type of work. Those might be like my personal biases speaking too because that’s like why I’m working on this direction.
Lucas Perry: Yeah. I think that’s deeply informative though for other people who might be trying to find their footing in determining how they ought to approach this problem. So how likely do you think it is that deep reinforcement learning scales up to AGI? What are the strongest considerations for and against that?
Jan Leike: I don’t think anyone really knows whether that’s the case or not. Deep learning certainly has a pretty convincing track record of fitting arbitrary functions. We can basically fit a function that knows how to play StarCraft. That’s a pretty complicated function. I think, well, whatever the answer is to this question, in safety what we should be doing is we should be conservative about this. Take the possibility that deep RL could scale to AGI very seriously, and plan for that possibility.
Lucas Perry: How modular do you think AGI will be and what makes you optimistic about having clearly defined components which do planning, reward modeling, or anything else?
Jan Leike: There’s certainly a lot of advantages if you can build a system of components that you understand really well. The way I currently picturing trying to build, say, a prototype for aligned AGI would be somewhat modular. The trend in deep learning is always towards training end-to-end. Meaning that you just have your raw data coming in and the raw predictions coming out and you just train some giant model that does all of that. That certainly gives you performance benefits on some tasks because whatever structure the model ends up learning can just be better than what the humans perceptions would recommend.
How it actually ends up working out is kind of unclear at the moment. I think in terms of what we’d like for safety is that if you have a modular system, it’s going to make it easier to really understand what’s going on there because you can understand the components and you can understand how they’re working together, so it helps you break down the problem of doing assurance in the system, so that’s certainly a path that we would like to work out
Lucas Perry: And is inner alignment here a problem that is relevant to both the modular components and then how the modular components are interrelated within the system?
Jan Leike: Yeah, I think you should definitely think about what the incentives are and what the training signals are of all of the components that you’re using to build a system.
Lucas Perry: As we approach AGI, what efforts are going on right now at DeepMind for AI safety benchmarking?
Jan Leike: We’ve spent some time thinking about AI safety benchmarks. We made a few little environments that are called gridworlds that are basically just kind of like chess board tiles where your agent moves around, and those are I think useful to showcase some of the problems. But really I think there’s a lot of appetite right now for building benchmark environments that let you test your agent on different properties. For example, OpenAI just recently released a collection of environments for safe exploration that require you to train in the presence of site constraints. But there’s also a lot of other properties that you could actually build tractable benchmarks for today.
So another example would be adversarial inputs, and there’s this generalized adversarial examples challenge. There’s also, you could build a benchmark for distributional shift, which in some ways you already do that in machine learning a lot where you do a little training in a test split, but usually these are on from the same decision. There’s various trans learning research going on. I don’t think there is really established benchmarks for those. This is certainly something that could be done.
There’s also problems that we worry about in longterm safety that I think would be kind of hard to really do good benchmarks on right now. Here I’m thinking of things like the off-switch problems, reward gaming, where you actually have an agent that can modify its own input rewards. The problem here is really you need very complex environments that are difficult to build and learn with current systems.
But I think overall this is something that would be very useful for the community to pursue, because the history of recent machine learning progress has always been that if you make a benchmark, people will start improving on the benchmark. The benchmark starts driving progress, and we’ve seen this with the ImageNet benchmark. We’ve seen that with the Atari benchmark, just to name two examples. And so if you had a safety benchmark, you would kind of incentivize people to make safety progress. Then if it’s an established benchmark, you can also publish on this. Then longer term, once you’ve had success with a bunch of benchmarks or they’ve been established and accepted, they could also become industry norms.
Lucas Perry: I’m just trying to understand how benchmarks in general, whether they’re safety benchmarks or not, exist in the international and national communities of computer science. Are Chinese computer scientists going to care about the DeepMind safety benchmarks? Are they something that necessarily are incorporated?
Jan Leike: Why do you think Chinese researchers care about the ImageNet benchmark?
Lucas Perry: Well, I don’t really know anything about the ImageNet benchmark.
Jan Leike: Oh, so the ImageNet is this big collection of labeled images that a lot of people train image classifiers on. So these are like pictures of various breeds of dogs and cats and so on. Things people are doing, or at least were doing for a while, was training larger and larger vision models on ImageNet and then you can measure what is your test accuracy of ImageNet and that’s a very tangible benchmark on how well you can do computer vision with your machine learning models.
Lucas Perry: So when these benchmarks are created, they’re just published openly?
Jan Leike: Yeah, you can just download ImageNet. You can just get started at trying a model on ImageNet in like half an hour on your computer.
Lucas Perry: So the safety benchmarks are just published openly. They can just be easily accessed, and they are public and open methods by which systems can be benchmarked to the degree to which they’re aligned and safe?
Jan Leike: Yeah. I think in general people underestimate how difficult environment design is. I think in order for a safety benchmark to get established, it actually has to be done really well. But if you do it really well and you can get a whole bunch of people interested because it’s becomes clear that this is something that is hard to do and methods can’t … but it’s also something that, let’s say if you made progress on it, you could write a paper or you can get employed at a company because you did something that people agreed was hard to do. At the same time, it has the result that is very easily measurable.
Lucas Perry: Okay. To finish up on this point, I’m just interested in if you could give a final summary on your feelings and interests in AI safety benchmarking. Besides the efforts that are going on right now, what are you hoping for?
Jan Leike: I think in summary I would be pretty excited about seeing more safety benchmarks that actually measure some of the things that we care about if they’re done well and if they really pay attention to a lot of detail, because I think that can drive a lot of progress on these problems. It’s like the same story as with reward modeling, right? Because then it becomes easy to evaluate progress and it becomes easy to evaluate what people are doing and that makes it easy for people to do stuff and then see whether or not whatever they’re doing is helpful.
Lucas Perry: So there appears to be cultural and intellectual differences between the AI alignment and AI safety communities and the mainstream AI community, people who are just probably interested in deep learning and ML.
Jan Leike: Yeah. So historically the machine learning community and the long term safety community have been somewhat disjoined.
Lucas Perry: So given this disjointedness, what would you like the mainstream ML and AI community to do or to think differently?
Jan Leike: The mainstream ML community doesn’t think enough about how whatever they are building will actually end up being deployed in practice, and I think people that are starting to realize that they can’t really do RL in the real world if they don’t do reward modeling, and I think it’s most obvious to robotics people trying to get robots to do stuff in the real world all the time. So I think reward modeling will become a lot more popular. We’ve already seen that in the past two years.
Lucas Perry: Some of what you’re saying is reminding me of Stuart Russell’s new book, Human Compatible. I’m curious to know if you have any thoughts on that and what he said there and how that relates to this.
Jan Leike: Yes. Stuart also has been a proponent of this for a long time. In a way, he has been one of the few computer science professors who are really engaging with some of these longer term AI questions, in particular around safety. I don’t know why there isn’t more people saying what he’s saying.
Lucas Perry: It seems like it’s not even just the difference and disjointedness between the mainstream ML and AI community and then the AI safety and AI alignment community is just that one group is thinking longterm and the other is not. It’s just a whole different perspective and understanding about what it means for something to be beneficial and what it takes for something to be beneficial. I don’t think you need to think about the future to understand the importance of recursive reward modeling or the kinds of shifts that Stuart Russell is arguing for given the systems which are being created today are already creating plenty of problems. We’ve enumerated those many times here. That seems to me to be because the systems are clearly not fully capturing what human beings really want. Just trying to understand better and also what you think the alignment and AI safety community should do or think differently to address this difference.
Jan Leike: The longterm safety community in particular, initially I think a lot of the arguments people made were very high level and almost philosophical, has been a little bit of a shift towards concrete mathematical, but also at the same time very abstract research, then towards empirical research. I think this is kind of a natural transition from one mode of operation to something more concrete, but there’s still some parts of the safety community in the first phases.
I think there’s a failure mode here where people just spend a lot of time thinking about what would be the optimal way of addressing a certain problem before they actually go out and do something, and I think an approach that I tend to favor is thinking about this problem for a bit and then doing some stuff and then iterating and thinking some more. That way you get some concrete feedback on whether or not you’re actually making progress.
I think another thing that I would love to see the community do more of is I think there’s not enough appreciation for clear explanations, and there’s a tendency that people write a lot of vague blog posts, and that’s difficult to critique and to build on. Where we really have to move as a community is toward more concrete technical stuff that you can clearly point at parts of it and be like, “This makes sense. This doesn’t make sense. He has very likely made a mistake,” then that’s something where we can actually build on and make progress with.
In general. I think this is the sort of community that attracts a lot of thinking from first principles, and there’s a lot of power in that approach. If you’re not bound by what other people think and what other people have tried, then you can really discover truly novel directions and truly novel approaches and ideas, but at the same time I think there’s also a danger of overusing this kind of technique, because I think it’s right to also connect what you’re doing with the literature and what everyone else is doing. Otherwise, you will just keep reinventing the wheel on some kind of potential solution to safety.
Lucas Perry: Do you have any suggestions for the AI safety and alignment community regarding also alleviating or remedying this cultural and intellectual difference between what they’re working on and what the mainstream ML and AI communities are doing and working on such that it shifts their mindset and work to increase the chances that more people are aware of what is required to create beneficial AI systems?
Jan Leike: Something that would be helpful for this bridge would be if the safety community as a whole, let’s say, spends more time engaging with the machine learning literature, the machine learning lingo and jargon, and try to phrase the safety ideas and the research in those terms and write it up in a paper that can be published in NeurIPS rather than something that is a blog post. The form is just a format that people are much more likely to engage with.
This is not to say that I don’t like blog posts. Blogs are great for getting some of the ideas across. We also provide blog posts about our safety research at DeepMind, but if you really want to dive into the technical details and you want to get the machine learning community to really engage with the details of your work, then writing a technical paper is just the best way to do that.
Lucas Perry: What do you think might be the most exciting piece of empirical safety work which you can realistically imagine seeing within the next five years?
Jan Leike: We’ve done a lot of experiments with reward modeling, and I personally have been surprised how far we could scale it. It’s been able to tackle every problem that we’ve been throwing at it. So right now we’re training agents to follow natural language instructions in these 3D environments that we’re building here at DeepMind. These are a lot harder problems than, say, Atari games, and reward modeling still is able to tackle them just fine.
One kind of idea what that prototype could look like is a model-based reinforcement learning agent where you learn a dynamics model then train a reward model from human feedback then the reinforcement learning agent uses the dynamics model and the reward model to do search at training and at test time. So you can actually deploy it in the environment and it can just learn to adapt its plans quickly. Then we could use that to do a whole bunch of experiments that we would want that system to do. You know like, solve off-switch problems or solve reward tampering problems or side effects, problems and so on. So I think that’d be really exciting, and I think that’s well within the kind of system that we could build in the near future.
Lucas Perry: Cool. So then wrapping up here, let’s talk a little bit about the pragmatic side of your team and DeepMind in general. Is DeepMind currently hiring? Is the safety team hiring? What is the status of all of that, and if listeners might be able to get involved?
Jan Leike: We always love to hire new people that join us in these efforts. In particular, we’re hiring research engineers and research scientists to help us build this stuff. So, if you, dear listener, have, let’s say, a Master’s degree in machine learning or some kind of other hands on experience in building and training deep learning systems, you might want to apply for a research engineering position. For a research scientist position the best qualification is probably a PhD in machine learning or something equivalent. We also do research internships for people who maybe have a little bit early in their PhD. So this is the kind of thing that applies to you and you’re excited about working on these sort of problems, then please contact us.
Lucas Perry: All right, and with that, thank you very much for your time, Jan.