Discussion moved here from One-Two-Three.
Alex Weldon: Like a lot of Go proverbs this one (don't play 1-2-3, just play 3 - see One-Two-Three) contradicts other advice, namely the idea of inducing moves. In Attack and Defence, James Davies says that if you want to play c, it is often better to look for a move that will induce a move from the opponent, which will, in turn, "force" you to play the move you wanted anyway. Basically, you're inducing the opponent to play a "thank you" move for you.
So, basically, this principle comes down to saying "inducing moves aren't always good." This makes sense, though, since things that look like kikashi aren't always good, either, if they're actually "thank you" moves.
I suppose the way to look at it is this: you're going to play anyway. Rather than automatically playing , , , consider and first. Imagine is already on the board, and you're considering playing , as a kikashi. If it is indeed kikashi, the 123 is probably good. If it's aji keshi, or otherwise helps White more than it helps Black, Black immediately at is better.
Charles In the case of a good inducing move, makes look better; in the case of a redundant 1-2-3, the point is that makes look unnecessary. As Alex suggests, the principle falls into the category of concepts of which one should be aware, and gradually learn to apply appropriately.
Confused: As a rather weak player, I have trouble understanding where this proverb should be applied and why. Does this proverb cover the following situation?
Well, this page is marked 'dan-level' and there's a reason for that. These ideas have more holes in them than most proverbs, if you insist on them as rules.
The discussion here, to be full enough to be useful, ought to include the crosscut then extend stuff (see discussion pages linked from there); because that's really just an important special case. But that hasn't been brought to a satisfactory conclusion, in my view.
What seems useful to say is:
The '123 principle' is a small-scale version of a key proverb beware of going back to patch up.
Kupopo: I'm certainly out of my league in this discussion, but according to the example at the bottom of canonical form, the sequence in the above example must continue with Black 3 at a and White 4 at one of several points inside his own territory, preventing a white invasion. Regardless of whether or not White a is better then before, it's Black's turn to play, and he may have to give up sente (but probably not) to take that point, thus stealing one or two points of territory from White. Am I missing something?
Charles Yes. The point is not whether Black may gain something by this play (he may); but whether Black has already gained something by getting White to answer.
Bill: As the author of the canonical form page, your comment alarmed me, Kupopo. I checked, and indeed the example on that page is different. at a is surely canonical, but somewhere inside his own territory is probably not, and may not be. One problem is that the diagram here is incomplete, so we cannot answer that question.
Bill: I am sorry for raising an objection, because I think that there is some useful advice here. Very often players, particularly kyu players, make unnecessary and even disadvantageous exchanges, which this warns against.
However, this piece of advice is not a principle, nor a proverb, nor a heuristic. If it were a principle we should have the following:
Charles The so-called principle is a sort of axiom of criticism, best as self-criticism, in a minimalist spirit.
Nothing like a good reductio ad absurdum, is there? Of course if applied literally this argument implies Black should play the final move of the game rather than .
That is not of course what is meant: here in the second diagram Black prefers to have exchanged for before playing .
To take this up in detail.
If not, we might plausibly get this position: all stronger players recognise that though this is safer for Black than playing a pincer, it is also unambitious.
In any case the point is that the / exchange in the first diagram is so far from redundant that it actually sets up the conditions for what follows. As is typical of opening moves, all subsequent stones should fit in; the early plays occupy 'high ground' of strategic importance.
I have added some amplification to the One-Two-Three page to expand on the principle.