The fascinating Facebook debate between Yann LeCun, Stu...

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The fascinating Facebook debate between Yann LeCun, Stuart Russel and Yoshua Bengio about the risks of strong AI

End of September 2019, a fascinating debate happened spontaneously in the comment section of a Facebook post.

Yann LeCun, Chief AI Scientist at Facebook, had posted an article he had co-written with Tony Zador (an American neuroscientist) entitled Don’t Fear the Terminator - Artificial intelligence never needed to evolve, so it didn’t develop the survival instinct that leads to the impulse to dominate others.

Soon a debate ensued between him, Stuart Russel and Yoshua Bengio.

Stuart Russel is a professor of Computer Science at the University of California, Berkeley. He's the author of one of the most used textbooks on AI, if not the most used. He's also known for warning people about the risks of Slaughterbots in a Youtube video that got more than 3 million views.

Yoshua Bengio is a professor at the Department of Computer Science and Operations Research at the Université de Montréal and scientific director of the Montreal Institute for Learning Algorithms (MILA).

Yann LeCun and Yoshua Bengio are often referred to as 2 of the 3 godfathers of modern AI and in particular deeplearning (along with Geoff Hinton). These 3 were awarded together the 2018 Turing Award for conceptual and engineering breakthroughs that have made deep neural networks a critical component of computing.

Both Yann LeCun, Yoshua Bengio and Stuart Russel were featured in that landmark book by Martin Ford : Architects of Intelligence: The truth about AI from the people building it

Here below are their contributions to the debate. (many other people participated but I didn't include them out of clarity, the full debate can be found here). I've retained some contributions from others that are helpful to understand the debate

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Chris Rose
What seems missing in all these musings is the impartial arbiter of physics. Let's take the simple:
In a fistfight, exactly what advantage does super-intelligence confer?
Then abstracting it out, paying attention to inviolable physical constraints, what advantage does super-intelligence convey over billions of years of evolution?
We can muse about both these things, but there are likely theorems lurking and that's what's needed.

Yann LeCun 
Physics has a way of setting limits on the power of intelligence.
First, there is a limit on how much computational power you can pack in a given volume (just because of thermal dissipation).
Second, there is a limit on communication bandwidth per volume (because of energy) and latency (because or light speed).
Hence there is a limit on the amount of computation per unit volume.

More importantly, the smarter the machine, the larger and more power hungry it will need to be, and the more vulnerable it will be to physical attacks.

Emilio Frangella 
I don't think we can predict the behavior of an intelligence that will be several orders of magnitude more advanced than the intelligence of the whole humanity combined.

Yann LeCun
A virus can't come close to predicting the behavior of your intelligence, which is several orders of magnitude more advanced than the combined intelligence of billions of viruses. 
But it can still kill you.
The point is that if we can build a super-intelligent AI that ends up threatening us (for some unforeseen reason), we can build another system, with access to the same amount of resources, whose only purpose will be to disable the first one. It will almost certainly succeed. For the same reason a virus can kill you. 

Elliot Olds 
Yann, the smart people who are very worried about AI seeking power and ensuring its own survival believe it’s a big risk because power and survival are instrumental goals for almost any ultimate goal.

If you give a generally intelligent AI the goal to make as much money in the stock market as possible, it will resist being shut down because that would interfere with its goal. It would try to become more powerful because then it could make money more effectively. This is the natural consequence of giving a smart agent a goal, unless we do something special to counteract this.

You’ve often written about how we shouldn’t be so worried about AI, but I’ve never seen you address this point directly.

Stuart Russell 
It is trivial to construct a toy MDP in which the agent's only reward comes from fetching the coffee. If, in that MDP, there is another "human" who has some probability, however small, of switching the agent off, and if the agent has available a button that switches off that human, the agent will necessarily press that button as part of the optimal solution for fetching the coffee. No hatred, no desire for power, no built-in emotions, no built-in survival instinct, nothing except the desire to fetch the coffee successfully. This point cannot be addressed because it's a simple mathematical observation

(MDP means markov decision process, ou processus de décision markovien : en théorie de la décision et en théorie des probabilités, un processus de décision markovien est un modèle stochastique où un agent prend des décisions et où les résultats de ses actions sont aléatoires.)

Yoshua Bengio 
Yann, I'd be curious about your response to Stuart Russell's point.

Yann LeCun 
You mean, the so-called "instrumental convergence" argument by which "a robot can't fetch you coffee if it's dead. Hence it will develop self-preservation as an instrumental sub-goal."
It might even kill you if you get in the way.

Once the robot has brought you coffee, its self-preservation instinct disappears. You can turn it off.
One would have to be unbelievably stupid to build open-ended objectives in a super-intelligent (and super-powerful) machine without some safeguard terms in the objective.
One would have to be rather incompetent not to have a mechanism by which new terms in the objective could be added to prevent previously-unforeseen bad behavior. For humans, we have education and laws to shape our objective functions and complement the hardwired terms built into us by evolution.
The power of even the most super-intelligent machine is limited by physics, and its size and needs make it vulnerable to physical attacks. No need for much intelligence here. A virus is infinitely less intelligent than you, but it can still kill you.
A second machine, designed solely to neutralize an evil super-intelligent machine will win every time, if given similar amounts of computing resources (because specialized machines always beat general ones).
Bottom line: there are lots and lots of ways to protect against badly-designed intelligent machines turned evil.

Stuart has called me stupid in the Vanity Fair interview linked below for allegedly not understanding the whole idea of instrumental convergence.
It's not that I don't understand it. I think it would only be relevant in a fantasy world in which people would be smart enough to design super-intelligent machines, yet ridiculously stupid to the point of giving it moronic objectives with no safeguards.

Here is the juicy bit from the article where Stuart calls me stupid:
<<Russell took exception to the views of Yann LeCun, who developed the forerunner of the convolutional neural nets used by AlphaGo and is Facebook’s director of A.I. research. LeCun told the BBC that there would be no Ex Machina or Terminator scenarios, because robots would not be built with human drives—hunger, power, reproduction, self-preservation. “Yann LeCun keeps saying that there’s no reason why machines would have any self-preservation instinct,” Russell said. “And it’s simply and mathematically false. I mean, it’s so obvious that a machine will have self-preservation even if you don’t program it in because if you say, ‘Fetch the coffee,’ it can’t fetch the coffee if it’s dead. So if you give it any goal whatsoever, it has a reason to preserve its own existence to achieve that goal. And if you threaten it on your way to getting coffee, it’s going to kill you because any risk to the coffee has to be countered. People have explained this to LeCun in very simple terms.” >>

Tony Zador 
I agree with most of what Yann wrote about Stuart Russell's concern.

Specifically, I think the flaw in Stuart's argument is the assertion that "switching off the human is the optimal solution"---who says that's an optimal solution?

I guess if you posit an omnipotent robot, destroying humanity might be a possible solution. But if the robot is not omnipotent, then killing humans comes at considerable risk, ie that they will retaliate. Or humans might build special "protector robots" whose value function is solely focused on preventing the killing of humans by other robots. Presumably these robots would be at least as well armed as the coffee robots. So this really increases the risk to the coffee robots of pursuing the genocide strategy.

And if the robot is omnipotent, then there are an infinite number of alternative strategies to ensure survival (like putting up an impenetrable forcefield around the off switch) that work just as well.

So i would say that killing all humans is not only not likely to be an optimal strategy under most scenarios, the set of scenarios under which it is optimal is probably close to a set of measure 0.

Stuart Russell 
Thanks for clearing that up - so 2+2 is not equal to 4, because if the 2 were a 3, the answer wouldn't be 4? I simply pointed out that in the MDP as I defined it, switching off the human is the optimal solution, despite the fact that we didn't put in any emotions of power, domination, hate, testosterone, etc etc. And your solution seems, well, frankly terrifying, although I suppose the NRA would approve. Your last suggestion, that the robot could prevent anyone from ever switching it off, is also one of the things we are trying to avoid.The point is that the behaviors we are concerned about have nothing to do with putting in emotions of survival, power, domination, etc. So arguing that there's no need to put those emotions in is completely missing the point.

Yann LeCun 
Not clear whether you are referring to my comment or Tony's.
The point is that behaviors you are concerned about are easily avoidable by simple terms in the objective. In the unlikely event that these safeguards somehow fail, my partial list of escalating solutions (which you seem to find terrifying) is there to prevent a catastrophe. So arguing that emotions of survival etc will inevitably lead to dangerous behavior is completely missing the point.

It's a bit like saying that building cars without brakes will lead to fatalities.
Yes, but why would we be so stupid as to not include brakes?

That said, instrumental subgoals are much weaker drives of behavior than hardwired objectives. Else, how could one explain the lack of domination behavior in non-social animals, such as orangutans.

Stuart Russell 
"Why would be build machines that are not aligned to our values?" That's what we are doing, all the time. The standard model of AI assumes that the objective is fixed and known (check the textbook!), and we build machines on that basis - whether it's clickthrough maximization in social media content selection or total error minimization in photo labeling (Google Jacky Alciné) or, per Danny Hillis, profit maximization in fossil fuel companies. This is going to become even more untenable as machines become more powerful. There is no hope of "solving the value alignment problem" in the sense of figuring out the right value function offline and putting it into the machine. We need to change the way we do AI.

Yoshua Bengio 
All right, we're making some progress towards a healthy debate. Let me try to summarize my understanding of the arguments. 
Yann LeCun and Tony Zador argue that humans would be stupid to put in explicit dominance instincts in our AIs. 
Stuart Russell responds that it needs not be explicit but dangerous or immoral behavior may simply arise out of imperfect value alignment and instrumental subgoals set by the machine to achieve its official goals. 
Yann LeCun and Tony Zador respond that we would be stupid not to program the proper 'laws of robotics' to protect humans. 
Stuart Russell is concerned that value alignment is not a solved problem and may be intractable (i.e. there will always remain a gap, and a sufficiently powerful AI could 'exploit' this gap, just like very powerful corporations currently often act legally but immorally). 
Yann LeCun and Tony Zador argue that we could also build defensive military robots designed to only kill regular AIs gone rogue by lack of value alignment. 
Stuart Russell did not explicitly respond to this but I infer from his NRA reference that we could be worse off with these defensive robots because now they have explicit weapons and can also suffer from the value misalignment problem.

So at the end of the day, it boils down to whether we can handle the value misalignment problem, and I'm afraid that it's not clear we can for sure, but it also seems reasonable to think we will be able to in the future. Maybe part of the problem is that Yann LeCun and Tony Zador are satisfied with a 99.9% probability that we can fix the value alignment problem while Stuart Russell is not satisfied with taking such an existential risk.

And there is another issue which was not much discussed (although the article does talk about the short-term risks of military uses of AI etc), and which concerns me: humans can easily do stupid things. So even if there are ways to mitigate the possibility of rogue AIs due to value misalignment, how can we guarantee that no single human will act stupidly (more likely, greedily for their own power) and unleash dangerous AIs in the world? And for this, we don't even need superintelligent AIs, to feel very concerned. The value alignment problem also applies to humans (or companies) who have a lot of power: the misalignment between their interests and the common good can lead to catastrophic outcomes, as we already know (e.g. tragedy of the commons, corruption, companies lying to have you buy their cigarettes or their oil, etc). It just gets worse when more power can be concentrated in the hands of a single person or organization, and AI advances can provide that power.

Tony Zador 
Stuart Russell "Thanks for clearing that up - so 2+2 is not equal to 4, because if the 2 were a 3, the answer wouldn't be 4? "
hmm. not quite what i'm saying.

If we're going for the math analogies, then i would say that a better analogy is:

Find X, Y such that X+Y=4.

The "killer coffee robot" solution is {X=642, Y = -638}. In other words: Yes, it is a solution, but not a particularly natural or likely or good solution.

But we humans are blinded but our own warped perspective. We focus on the solution that involves killing other creatures because that appears to be one of the main solutions that we humans default to. But it is not a particularly common solution in the natural world, nor do i think it's a particularly effective solution in the long run.

Yann LeCun 
Humanity has been very familiar with the problem of fixing value misalignments for millenia.
We fix our children's hardwired values by teaching them how to behave.
We fix human value misalignment by laws. Laws create extrinsic terms in our objective functions and cause the appearance of instrumental subgoals ("don't steal") in order to avoid punishment. The desire for social acceptance also creates such instrumental subgoals driving good behavior.
We even fix value misalignment for super-human and super-intelligent entities, such as corporations and governments.
This last one occasionally fails, which is a considerably more immediate existential threat than AI.

Tony Zador 
Yoshua Bengio I agree with much of your summary. I agree value alignment is important, and that it is not a solved problem.

I also agree that new technologies often have unintended and profound consequences. The invention of books has led to a decline in our memories (people used to recite the entire Odyssey). Improvements in food production technology (and other factors) have led to a surprising obesity epidemic. The invention of social media is disrupting our political systems in ways that, to me anyway, have been quite surprising. So improvements in AI will undoubtedly have profound consequences for society, some of which will be negative.

But in my view, focusing on "killer robots that dominate or step on humans" is a distraction from much more serious issues.

That said, perhaps "killer robots" can be thought of as a metaphor (or metonym) for the set of all scary scenarios that result from this powerful new technology.

Yann LeCun 
Stuart Russell you write "we need to change the way we do AI". The problems you describe have nothing to do with AI per se.
They have to do with designing (not avoiding) explicit instrumental objectives for entities (e.g. corporations) so that their overall behavior works for the common good. This is a problem of law, economics, policies, ethics, and the problem of controlling complex dynamical systems composed of many agents in interaction.
What is required is a mechanism through which objectives can be changed quickly when issues surface. For example, Facebook stopped maximizing clickthroughs several years ago and stopped using the time spent in the app as a criterion about 2 years ago. It put in place measures to limit the dissemination of clickbait, and it favored content shared by friends rather than directly disseminating content from publishers.

We certainly agree that designing good objectives is hard. Humanity has struggled with designing objectives for itself for millennia. So this is not a new problem. If anything, designing objectives for machines, and forcing them to abide by them will be a lot easier than for humans, since we can physically modify their firmware.
There will be mistakes, no doubt, as with any new technology (early jetliners lost wings, early cars didn't have seat belts, roads didn't have speed limits...).
But I disagree that there is a high risk of accidentally building existential threats to humanity.
Existential threats to humanity have to be explicitly designed as such.

Yann LeCun 
It will be much, much easier to control the behavior of autonomous AI systems than it has been for humans and human organizations, because we will be able to directly modify their intrinsic objective function.
This is very much unlike humans, whose objective can only be shaped through extrinsic objective functions (through education and laws), that indirectly create instrumental sub-objectives ("be nice, don't steal, don't kill, or you will be punished").

As I have pointed out in several talks in the last several years, autonomous AI systems will need to have a trainable part in their objective, which would allow their handlers to train them to behave properly, without having to directly hack their objective function by programmatic means.

Yoshua Bengio 
Yann, these are good points, we indeed have much more control over machines than humans since we can design (and train) their objective function. I actually have some hopes that by using an objective-based mechanism relying on learning (to inculcate values) rather than a set of hard rules (like in much of our legal system), we could achieve more robustness to unforeseen value alignment mishaps. In fact, I surmise we should do that with human entities too, i.e., penalize companies, e.g .fiscally, when they behave in a way which hurts the common good, even if they are not directly violating an explicit law. This also suggests to me that we should try to avoid that any entity (person, company, AI) have too much power, to avoid such problems. On the other hand, although probably not in the near future, there could be AI systems which surpass human intellectual power in ways that could foil our attempts at setting objective functions which avoid harm to us. It seems hard to me to completely deny that possibility, which thus would beg for more research in (machine-) learning moral values, value alignment, and maybe even in public policies about AI (to minimize the events in which a stupid human brings about AI systems without the proper failsafes) etc.

Yann LeCun 
Yoshua Bengio, if we can build "AI systems which surpass human intellectual power in ways that could foil our attempts at setting objective functions", we can also build similarly-powerful AI systems to set those objective functions.
Sort of like the discriminator in GANs...

Yoshua Bengio a couple direct comments on your summary:
- designing objectives for super-human entities is not a new problem. Human societies have been doing this through laws (concerning corporations and governments) for millennia.
- the defensive AI systems designed to protect against rogue AI systems are not akin to the military, they are akin to the police, to law enforcement. Their "jurisdiction" would be strictly AI systems, not humans.
But until we have a hint of a beginning of a design, with some visible path towards autonomous AI systems with non-trivial intelligence, we are arguing about the sex of angels.

Yoshua Bengio
Yann LeCun, about discriminators in GANs, and critics in Actor-Critic RL, one thing we know is that they tend to be biased. That is why the critic in Actor-Critic is not used as an objective function but instead as a baseline to reduce the variance. Similarly, optimizing the generator wrt a fixed discriminator does not work (you would converge to a single mode - unless you balance that with entropy maximization). Anyways, just to say, there is much more research to do, lots of unknown unknowns about learning moral objective functions for AIs. I'm not afraid of research challenges, but I can understand that some people would be concerned about the safety of gradually more powerful AIs with misaligned objectives. I actually like the way that Stuart Russell is attacking this problem by thinking about it not just in terms of an objective function but also about uncertainy: the AI should avoid actions which might hurt us (according to a self-estimate of the uncertain consequences of actions), and stay the conservative course with high confidence of accomplishing the mission while not creating collateral damage. I think that what you and I are trying to say is that all this is quite different from the terminator scenarios which some people in the media are brandishing. I also agree with you that there are lots of unknown unknowns about the strengths and weaknesses of future AIs, but I think that it is not too early to start thinking about these issues.

Stuart Russell 
Yann's comment "Facebook stopped maximizing clickthroughs several years ago and stopped using the time spent in the app as a criterion about 2 years ago" makes my point for me. Why did they stop doing it? Because it was the wrong objective function. Yann says we'd have to be "extremely stupid" to put the wrong objective into a super-powerful machine. Facebook's platform is not super-smart but it is super-powerful, because it connects with billions of people for hours every day. And yet they put the wrong objective function into it. QED. Fortunately they were able to reset it, but unfortunately one has to assume it's still optimizing a fixed objective. And the fact that it's operating within a large corporation that's designed to maximize another fixed objective - profit - means we cannot switch it off.

Regarding "externalities" - when talking about externalities, economists are making essentially the same point I'm making: externalities are the things not stated in the given objective function that get damaged when the system optimizes that objective function. In the case of the atmosphere, it's relatively easy to measure the amount of pollution and charge for it via taxes or fines, so correcting the problem is possible (unless the offender is too powerful) In the case of manipulation of human preferences and information states, it's very hard to assess costs and impose taxes or fines. The theory of uncertain objectives suggests instead that systems be designed to be "minimally invasive", i.e., don't mess with parts of the world state whose value is unclear. In particular, as a general rule it's probably best to avoid using fixed-objective reinforcement learning in human-facing systems, because the reinforcement learner will learn how to manipulate the human to maximize its objective.

Yann LeCun, let's talk about climate change for a change. Many argue that it's an existential or near-existential threat to humanity. Was it "explicitly designed" as such? We created the corporation, which is a fixed-objective maximizer. The purpose was not to create an existential risk to humanity. Fossil-fuel corporations became super-powerful and, in certain relevant senses, super-intelligent: they anticipated and began planning for global warming five decades ago, executing a campaign that outwitted the rest of the human race. They didn't win the academic argument but they won in the real world, and the human race lost. I just attended an NAS meeting on climate control systems, where the consensus was that it was too dangerous to develop, say, solar radiation management systems - not because they might produce unexpected disastrous effects but because the fossil fuel corporations would use their existence as a further form of leverage in their so-far successful campaign to keep burning more carbon.

Yann LeCun, this seems to be a very weak argument. The objection raised by Omohundro and others who discuss instrumental goals is aimed at any system that operates by optimizing a fixed, known objective; which covers pretty much all present-day AI systems. So the issue is: what happens if we keep to that general plan - let's call it the "standard model" - and improve the capabilities for the system to achieve the objective? We don't need to know today *how* a future system achieves objectives more successfully, to see that it would be problematic. So the proposal is, don't build systems according to the standard model.

Yann LeCun 
Stuart Russell the problem is that essentially no AI system today is autonomous.
They are all trained *in advance* to optimize an objective, and subsequently execute the task with no regards to the objective, hence with no way to spontaneously deviate from the original behavior.
As of today, as far as I can tell, we do *not* have a good design for an autonomous machine, driven by an objective, capable of coming up with new strategies to optimize this objective in the real world.
We have plenty of those in games and simple simulation. But the learning paradigms are way too inefficient to be practical in the real world.

Stuart Russell, in pretty much everything that society does (business, government, of whatever) behaviors are shaped through incentives, penalties via contracts, regulations and laws (let's call them collectively the objective function), which are proxies for the metric that needs to be optimized.
Because societies are complex systems, because humans are complex agents, and because conditions evolve, it is a requirement that the objective function be modifiable to correct unforeseen negative effects, loopholes, inefficiencies, etc.
The Facebook story is unremarkable in that respect: when bad side effects emerge, measures are taken to correct them. Often, these measures eliminate bad actors by directly changing their economic incentive (e.g. removing the economic incentive for clickbaits).
Perhaps we agree on the following:
(0) not all consequences of a fixed set of incentives can be predicted.
(1) because of that, objectives functions must be updatable.
(2) they must be updated to correct bad effect whenever they emerge.
(3) there should be an easy way to train minor aspects of objective functions through simple interaction (similar to the process of educating children), as opposed to programmatic means.
Perhaps where we disagree is the risk of inadvertently producing systems with badly-designed and (somehow) un-modifiable objectives that would be powerful enough to constitute existential threats

Yoshua Bengio 
Yann LeCun this is true, but one aspect which concerns me (and others) is the gradual increase in power of some agents (now mostly large companies and some governments, potentially some AI systems in the future). When it was just weak humans the cost of mistakes or value misalignment (improper laws, misaligned objective function) was always very limited and local. As we build more and more powerful and intelligent tools and organizations, (1) it becomes easier to cheat for 'smarter' agents (exploit the misalignment) and (2) the cost of these misalignments becomes greater, potentially threatening the whole of society. This then does not leave much time and warning to react to value misalignment.