6 ms·
The post is long and complicated and I haven't read most of it, so whether it's actually any good I shan't try to decide. But the above seems like a very weird
by gjm11 3y ago
The post is long and complicated and I haven't read most of it, so whether it's actually any good I shan't try to decide. But the above seems like a very weird argument.
Sure, the code is doing what it's doing. But trying to understand it at that level of abstraction seems ... not at all promising.
Consider a question about psychology. Say: "What are people doing when they decide what to buy in a shop?".
If someone writes an article about this, drawing on some (necessarily simplified) model of human thinking and decision-making, and some experimental evidence about how people's purchasing decisions change in response to changes in price, different lighting conditions, mood, etc., ... would you say "You can just apply the laws of physics and see what the people are doing. They're not doing something more or less than that."?
I mean, it would be true. People, so far as we know, do in fact obey the laws of physics. You could, in principle, predict what someone will buy in a given situation by modelling their body and surroundings at the level of atoms or thereabouts (quantum physics is a thing, of course, but it seems likely that a basically-classical model could be good enough for this purpose). When we make decisions, we are obeying the laws of physics and not doing some other thing.
But this answer is completely useless for actually understanding what we do. If you're wondering "what would happen if the price were ten cents higher?" you've got no way to answer it other than running the whole simulation again. Maybe running thousands of versions of it since other factors could affect the results. If you're wondering "does the lighting make a difference, and what level of lighting in the shop will lead to people spending least or most?" then you've got no way to answer it other than running simulations with many different lighting conditions.
Whereas if you have a higher-level, less precise model that says things like "people mostly prefer to spend less" and "people try to predict quality on the basis of price, so sometimes they will spend more if it seems like they're getting something better that way" and "people like to feel that they're getting a bargain" and so on, you may be able to make predictions without running an impossibly detailed person-simulation zillions of times. You may be able to give general advice to someone with a spending problem who'd like to spend more wisely, or to a shopkeeper who wants to encourage their customers to spend more.
Similarly with language models and similar systems. Sure, you can find out what it does in some very specific situation by just running the code. But what if you have some broader question than that? Then simply knowing what the code does may not help you at all, because what the code does is gazillions of copies of "multiply these numbers together and add them".
Again, I make no claim about whether the particular thing linked here offers much real insight. But it makes zero sense, so far as I can see, to dismiss it on the grounds that all you need to do is read the code.
- xanderlewis 3y agoYou’re spot on; it’s like saying you can understand the game of chess by simply reading the rules. In a certain very superficial sense, yes. But the universe isn’t so simple. The same reason even a perfect understanding of what goes on at the level of subatomic particles isn’t thought to be enough to say we ‘understand the universe’. A hell of a lot can happen in between the setting out of some basic rules and the end — much higher level — result.
- danielmarkbruce 3y agoAnd yet...alpha zero.
- xanderlewis 3y agoMy entire point is that implementation isn’t sufficient for understanding. Alpha Zero is the perfect example of that; you can create an amazing chess playing machine and (potentially) learn nothing at all about how to play chess. …so what’s your point? I’m not getting it from those two words.
- danielmarkbruce 3y agoUnderstanding how the machine plays or how you should play? They aren't the same thing. And that is the point - trying to analogize to some explicit, concrete function you can describe is backwards. These models are gigantic (even the 'small' ones), they are looking to minimize a loss function by looking in multi thousand dimensional space. It is the very opposite of something that fits in a human brain in any explicit fashion.
- gjm11 3y agoSo is what happens in an actual literal human brain. And yet, we spend quite a lot of our time thinking about what human brains do, and sometimes it's pretty useful. For a lot of this, we treat the actual brain as a black box and don't particularly care about how it does what it does, but knowing something about the internal workings at various levels of abstraction is useful too. Similarly, if for whatever reason you are interested in, or spend some of your time interacting with, transformer-based language models, then you might want some intuition for what they do and how. You'll never fit the whole thing in your brain. That's why you want simplified abstracted versions of it. Which, AIUI, is one thing that the OP is trying to do. (As I said before, I don't know how well it does it; what I'm objecting to is the idea that trying to do this is a waste of time because the only thing there is to know is that the model does what the code says it does.)