Indeed there seem to be two possible interpretations of "general" being used here.
1) General = "Often true"
2) General = "Always true without exceptions or with an explicit and complete enumeration of the exceptions"
The first is the common usage in everyday speech. The second also appears in everyday speech but appears most frequently in mathematics.
I suggest that the first meaning be adopted in the remainder of this thread (but not for future threads). We can perhaps use the term "universal" when intending the second meaning.
Under such conventions, two
general principles may contradict each other but two
universal principles may not.
Examples of general principles:
- Hane at the head of two stones
- From a wall of two, extend three
- Play at the point of symmetry
Examples of universal principles:
- A contiguous string of stones surrounding a contiguous string of empty points 4 long and without any bends (i.e., a "straight four") is unconditionally alive.
- A go board is worth 10.32 gobans.
Universal principles are not only fewer in number than general principles, but also more difficult to state properly.
I think that we can all agree that both types are useful as long as we understand them for what they are.
Universal principles can be used as shortcuts to speed up calculation (reading). General principles can be used to find candidates branches to read out first since we cannot read every possible variation. In one popular 4-4 one-space pincer 3-3 invasion joseki, the general principle "hane at the head of two stones" is violated. Someone who does not know this joseki may consider this hane as a candidate move, but will reject it if he has carefully read out the sequences that start with it. Does this mean that the general principle is bad? No. If the hane works with sufficiently high frequency, the player will earn back the time he lost reading out the hane in the long run. Of course, what is a good general principle may change with what kind of moves most people are playing at any given moment in time, but, as amateurs, we do not need to conscious innovators of game play.
If general principles reflect the Bayesian posterior beliefs of collective experience of past go players, then pattern recognition built up by playing games (or replaying pro games) might reflect the Bayesian posterior beliefs of individual experience.
I don't know what further conclusions to draw... It seems that the transmission of go skills is a very difficult task that is still far from being understood. However, this sort of question is not unique to the go world. Effective transfer of cognitive skills is one of the white whales of business education. The case study method, which is the most commonly used, often ends up giving students a bad habit of digging up the solution used in a known case that is closest to the one they are facing. Most MBAs fail to recognize that the case-to-solution correspondence is not a continuous one.
One conjecture that feels right: Pattern recognition learning is probably more efficient in games with smaller boards. That is, reviewing a database of 2,000 pro games on a 13x13 board is probably exponentially more helpful for getting better at 13x13 games than reviewing a database of 2,000 pro games on a 19x19 board is for getting better at 19x19 games. I imagine that this has something to do with the attention that pattern recognition has received in the chess world.