Opening theory: Why principles are never enough

Unless you've been living under a rock over the weekend, or otherwise avoiding all chess news, you probably know that Fabiano Caruana beat Alireza Firouzja in 9 moves the other day. You may not know that Firouzja went on to win the match 3-2, because that wasn't what grabbed the headlines. A SuperGrandmaster didn't know a 100-year-old trap! Since that's only tangentially related to the point of this post, I'll link you a video from agadmator if you're interested in the game:

One reason this created so much buzz is that we expect the top GMs to just know this stuff. It certainly wouldn't have happened the other way around - nobody out-prepares Caruana! Opening traps are supposed to be a gimmick of us mere mortals - the Under 2000 club; the titled players are (we assume) "booked up". Any occasion where they are so obviously not demands attention; this author couldn't ignore it. Had it not been for that, I would have begun this post by returning for a more in-depth look at a position I touched on last week:

As you go down through the ratings, 6.Qxb6 overtakes 6.Qc2 as the most common move, at least partly because some players use the London opening as a substitute for knowing theory. It is seen as a "setup" opening where White can make the same general 9 first moves or so - a little deviance depending on what Black does, but not much. 4...Qb6 upsets this rhythm as it creates a concrete threat that needs dealt with. White thinks he has dealt with this favourably, but hasn't, and now we're thinking about the following ideas:

Do the arrows look busy? The point is that we have similar ideas and threats on the Kingside. I'll be attacking down the Queenside, as I explained last week, but that's beside the point. I'm thinking about getting my knight to h5 and winning the bishop pair. I'll need to play h6 to achieve this or the dark-squared bishop can escape with Bg5. The pawn move will have another motive: I want to play Bf5, and take control of that juicy b1-h7 diagonal, but White can use the same idea against me with Nh4 (since I'll need to play e6 at some point). Pawn to h6 allows Bh7. What if I play Bf5 immediately instead of Nf6?

This looks wrong, as I haven't prepared the move with h6. I am also violating an opening principle: develop knights before bishops. What I missed is that again, Bf5 would create a threat: an exchange on b1, followed by Rxa2. Since White will have to spend a move to deal with this, I have plenty time to push h6 - if I even need to, because I haven't committed with e6 yet. Here is one continuation:

Now, to give you a breather from what has become, if not a "deep dive", then certainly an initial submersion into London theory, I'll add some context in what inspired me to write this post. If you're here for pure chess, skip to the next diagram. This week, I've been dipping into the forums, and offering advice here and there. On one such occasion, I suggested to a 500 ELO player that they learn some opening theory. A stronger player than me responded by asking what good theory would do when you'll get taken out of book on Move 5. Now, they had a point: there is a conventional wisdom among coaches that you don't waste time teaching students opening theory below a certain ELO. Their pattern recognition has not developed to a point where they will be able to internalise all but the most basic points; you need to develop other skills first before they are ready to properly learn openings. Better to learn opening principles, as these can be applied in any game, and nobody will get very far without knowing them. Anyone remember how dodgy computers used to be in the opening once they were taken out of book? Besides, players with 500 ELO are losing their games because of nothing to do with the opening.

I don't disagree that opening principles are of fundamental importance. Any student that doesn't know them needs taught them pronto. I'm not arguing that principles are anything other than essential, because you'll always get taken out of [your] theory sooner or later. You need something to fall back on. But that's what opening principles should be: guidelines to help you when the game you're playing has strayed beyond the realms of what you already know. If that's happening 2 moves in, you don't know enough. You also can (and should) use them when you're starting out, before you've had the chance to learn any theory. But they are not a replacement. Principles can only get you so far, and you will need to understand at least a handful of openings to take you the rest of the way. We have seen, from the examples above, both players miss the right idea because they didn't know the theory as well as they should. I knew better than my opponent, but still missed 7...Bf5. To illustrate the point, let's come round to White's side of the table and look at what he should do:

The chances of White finding this plan if they haven't learned it are remote. Remember: there is a good chance that White was playing the London in the first place because they didn't want to learn theory. But that doesn't get them off the hook! They still need to know this, or they will struggle. At the very least, they'll take time on their clock, figuring out what to do. By the way, if you're wondering why Black sacrificed a pawn first before Bf5:

Similar to White's situation, how many players with the black pieces are going to play into this unless they've properly learned it? If you look at an engine analysis of the above line of what White should do when Black correctly sacrifices on e5 first, it sways between 0.0 and a slight advantage for Black. So why would White play the London at all, then? Well, again, theory would help the White side here. It's not a setup that you can just play in any order. Know the lines, and you can avoid the ones you don't want. For example, here is another recent game I played against the London:

So, as Black, I need to adjust my strategy to the particular order White is playing their moves. That would be difficult if I didn't know the various plans I might employ. By the way, before this post leaves the shores of the Thames (I guess), I don't want to give you the impression that all players who play the London are theory dodgers. Many have studied it extensively to get the best out of it. Indeed, here is a game I played online where I used the London:

White to play and win at least a pawn? Full disclosure: I did not play this move, even though I saw it (and knew to look for it because of theory). I preferred to connect rooks, and Black did nothing to address the threat that would have been a good move on Move 11, and still worked on move 12: Nxf7! - and once the knight is captured, the d6 bishop hangs.

Cut to the chase, Alisdair. Why are opening principles not enough?

In a nutshell, because there is a whole sub-section of theory devoted to taking advantage of the player who knows principles and nothing else. Consider one of the first openings we get shown to teach us principles when we're beginners:

So we see the themes are well learned here. I have played 1...e5 in response to 1.e4 many times, but haven't touched the Damiano defence with a 10-foot pole. However, if we tweak the opening a bit:

This time, the strange-looking pawn push to f6 is the only move that works, as Black needs to protect the e5 pawn and cover the g5 square. Nc6/d6/Bd6/Qe7/Qf6 all lose to Ng5! Opening traps exist in the weird void between theory and principles, where the opponent is taken out of book, and the principles don't work. Here is an example of me falling victim to that just this week:

Don't get any ideas, if you're playing White against me. Fool me once, and all that. I have since looked up how to deal with this. The Sicilian is still a relatively new opening for me, and I didn't have all the lines down. Er... I mean, I STILL haven't learned this one, if you're playing White against me, you should TOTALLY go for this line!!

I'm sure I could have used better examples, but we're all familiar with these offbeat openings where the opponent needs to find counterintuitive moves, right? I don't really want to reveal my prep where I deliberately hang three pieces to get a forced mate in 17. (Um... I probably shouldn't have put it on my profile then). But ultimately, someone who is following principles which work to varying degrees is going to be beaten by someone who KNOWS the position - it's just logic. An example from my favourite opening to round off with: