(Moved from second section)
SnotNose: Can't this difference be eliminated? It seems like one of attitude and patience. Maybe it should be in the previous list?
Charles Well, this was actually provoked by the way the Reference games were chosen: let's take a Takemiya, Go Seigen, Jowa and so on. Now tell me honestly - who in amateur circles really knows enough to put together a study package?
SnotNose: I so strongly disagree that your original statement belongs in this second list and not the first that I feel I must not be understanding it. Maybe putting it in other words would help. Anyway, I still don't follow. We have to make choices to do anything. Some choices can be made based on a "rational understanding" because we know enough to do so. Sometimes we are faced with situations where a choice must be made but we can't make it rationally, though we are willing to belive that someone (with more knowledge or skill) could make it rationally. We can be honest about this and then still make a choice (could be a random one). But a choice must be made so we can move on. So, we choose some set of games to study, say. Which ones and why? We don't have a good way of selecting. But, once selected are there not elements of each that can be studied ratioinally? Sure!! By doing this am I attempting to "digest the most inaccessible and impractical things?" No. Not by a long shot. I'm attempting to digest what I can digest and leave to chance (or some other arbitrary rule) that which I cannot. There's no problem here. Amateurs can eliminate the useless "study" of ideas that are so far beyond them that they're not really capable of studying them (Takemiya's cosmic style go may well be one of them, just as an example).
Charles OK then - suppose go isn't about power. How many amateurs could then study it? A very high proportion of good amateurs do take it be about power. Suppose that isn't a fundamental.
SnotNose: Ack (sound of a brain in spasm). Ok, suppose it isn't about power. How many amateurs could then study it? Many many many many. I think amateurs are more flexible of mind than you suggest. Anyway, do pros agree what it is about, fundamentally? (I would be surprised if it were about just one thing, rather than the balance of many ideas...but that's another topic.) My last words on this will be: (1) I still don't follow you Charles. Maybe I am incapable of it. I'll take the blame there and resign while I still have a shred of dignity :). (2) I contend that I do "study on the basis that rational understanding is possible and worthwhile; rather than attempting to digest the most inaccessible and impractical things." I can't imagine not studying on this basis. If, for a second, I thougth that my study was irrational or not worthwhile or that I was attempting to digest inaccessible or impractical things, I'd stop and do something else. I can't possibly belive this and still go on. Those who can bewilder me. Since I believe I do this, I think this is not a difference between pros and amateurs that connot be closed. But, I refer back to point (1). Perhaps this is a difference between Charles and SnotNose that can't be closed. So be it.
RafaelCaetano: If that makes you feel better, I also have no idea of what Charles is talking about.
Warp: One book which helped me a lot to understand one of the main things which make pros so strong compared to amateurs was The Direction of Play. Until reading that book I didn't really know what is it that makes pros so incredibly strong (naturally they have lots of experience, reading skills, etc etc, but that didn't seem to be all of it). Some people belittle this book, probably because of its sometimes pompous (and even rude) style, but I really recommend reading it to anyone who wants to understand why pros are so strong as they are. It really enlightened me. (I don't really know if it helped me to be a stronger player, though, but the enlightenment was rewarding enough in itself.)
Charles 'Fraid admiration for Kajiwara is probably in the same category as thinking it would be cool to understand Jowa's games. As far as I understand it, he was respected by other pros for his intensity in getting the maximum local plays. But the strategic application of the same idea - which the book is ostensibly about - is perhaps dubious (evidenced by Kobayashi Koichi's career, and Cho Hun-hyeon's aversion).
My reason for saying what I did is the analogy with academic careers, where the advice one gets on direction is hugely important, and rarely remarked on.
Velobici: Charles, could you expand on the above comments regarding Kobayashi Koichi and Cho Hun-hyeon, please.
Charles Kobayashi attended, when young, Kajiwara's study group. His early pro games are in a highly aggressive style. It looks very much as if he became genuinely strong when he dropped attacking play for his later, 'miserly' style: while retained the 'drill' local work ethic for his stones. Cho comments in his book that he thought Kajiwara's fuseki teachings were obscurantist: impossible to get hold of.
BobMcGuigan: One of the most impressive pro-experiences I've had was watching them play fairly fast games against strong amateurs, say AGA 7-Dan or a little stronger. I watched a pro playing a two stone game against such a player at a US Go Congress once. The pro made several moves during the opening which looked kind of luke warm but, when some serious fighting broke out in the middle game some 40 or 50 moves later, somehow these stones were in just the right places to help him in the fight. So, rather than encyclopedic knowledge of joseki or rapid deep reading, which most pros certainly have, I am most impressed by their knowledge of shape and positional judgement.
Charles I'm glad this proves somewhat contentious.
If I can add a possible summary: necessary conditions for amateurs to come close to pro level aren't hard to specify. They can be read out of other games, sport and so on. It doesn't make much sense to talk about pros who aren't technically strong. But sufficient conditions - a whole set of them, with real explanatory value: it might be beyond us to understand.
I expect another storm to break ...
SnotNose: This page wasn't intended to describe how an amateur can come close to pro level play, but if one wishes to use it (or view it) that way, it can't be stopped. The intention was to document some ways that amateurs play that pros do not and which can easily be changed. My hypothesis is that there are some basic things (Kageyama would call them fundamentals) that pros do that amateurs can emulate. By doing so, amateurs will become stronger and might improve faster. And these basic things are, in many cases, not hard to do. They're good habits, really. And, I'm not talking about blindly copying pro play or memorizing joseki. I'm talking about more basic approaches to play (as in the first list).
Charles Problem is, it's written by amateurs. I may be jaded; but I think amateur insight into pro go is fairly rubbishy. So I made some provocative remarks above.
SnotNose: A valid point. We're really comparing amateur habits to hypothesized pro ones. Still, even if we're wrong, the comparison is useful if it helps amateurs see the value of good habits. I am a strong beliver in the idea that if one wishes to improve in something, one should eliminate all possible barriers to improvement, even if they seem small. After all, if you eliminate a lot of small stuff, it adds up! Second, I believe Kageyama implied thesis in LessonsInTheFundamentalsOfGo that a significant part of professionalism is one of attitude. One can have (or at least mimic) a professional attitude even toward something outside of one's profession. Mostly it is a matter of taking the endevor seriously and, in some sense, respecting it (not doing things that trivialize it). Viewing anything in the way a professional might can help one become much better at it, if only because one maximizes one's efforts. Time is not wasted fooling around doing things that don't help. So, asking oneself "could I imagine a professional doing this?" is worthwhile. It is more or less the same as asking "am I taking this seriously? Can I do better?"
kokiri I think that attitude is something that is often only really tangentially considered.
I remember reading in the British Go Journal (I think) a dan player saying that hardcore reading skills are really only needed once or twice in a game, whereas the vast majority of the moves in a game are played by instinct, so this is an important 'skill' to develop.
The other side of the coin is the fact that a lot of games at levels approaching shodan seem dissolve into fights where no-one knows the outcome.
Is there some point where the rationale of playing ceases to be an animalistic 'this looks good, this looks good, this looks right... oh I'm in a ko fight, now where do I have any good ko threats...' and flips into a more rational 'this way of playing looks ok - oh, it leads to ko. I don't have enough ko threats, so I'll try this line instead'?
One thing that makes me mad is when people (usually my father) play a move inside a small group during the endgame at the same time as saying 'I don't think I need to play here'.
I think it's a difference between a result based approach (I'm winning by about 15 so I don't need to take any chances) vs. a learning based approach (I can't see any weakness, I'm going to trust my judgement) and I'm firmly in the latter camp.
Charles I like the way we have overviews at SL: this is almost something distinctive about the site, and sometimes the debates seem almost to justify the importance attached to some 'master term' (such as haengma, nerai. thickness, temperature ...). This page is another such attempt really. Or the dictionaries page: it might be simpler, if brutal, to say the pros know all that stuff (and we don't, and that's the difference).
But what is even better, really, is that all these big-scale discussions speak to significantly different facets. Food for thought.
John F. As a linguist I've always been able to see great parallels between language and go, both in how it's learnt and ways of thinking about it (moves as verbs and nouns, building in to phrases and clauses - there IS a grammar to go). But what has always struck me even more is the way so many families produce ranks of good go players. There are numerous examples of brothers and sisters, fathers and sons, etc becoming pro. But this is only the tip of an iceberg. There is a much, much vaster corpus of players who have siblings who reach high (usually very high) amateur dan level before drifting off to another career. I came across another one tonight, funnily enough - Mannami Kana's sister was strong enough to be instrumental in the career of the new prodigy Iyama Yuta.
At one time I thought this may have been a feature of go, but there are quite a few examples in shogi (though I sense that the relative numbers are far fewer). I thought for a time it was a Japanese thing, but it's common in Korea, China and Taiwan.
As far as I can tell, it's uncommon in chess. The Polgar experiment is not only exceptional, it's somewhat artificial.
I'm pretty certain I'm right in saying that when this parallel sibling development happens in go, the siblings who don't go on to be pro are almost invariably very strong amateurs. For example, Go Seigen's brothers were early 7d amateurs, Kitani Reiko's brothers were 5d (one became a doctor instead).
I infer, therefore, that reaching a very high amateur grade is possible, even likely, without a great deal of effort if you start young and (I imagine) live in the right environment, and having brothers and sisters who play can be a big factor. The reason I say "without a great deal of effort" is that this parallels how children can pick up a second language in a bilingual environment, but the evidence of biographies and anecdotes bears this out anyway. 
Possibly it can also be inferred that the obsessional nature of some pros when they were young is not what made them strong players, but rather what made them choose go as a profession.
Where there are multiple players in a family down the generations as opposed to across one generation, it is noticeable that one generation can be very strong but the adjancent ones tend to be weak (at pro level, one pro may end up as nothing more than a lesson pro; if the player stays as amateur he seems to end up as no more than 2d or 1d (by the by, this was the case with GSG - his father was about amateur 1d, his son never got past 2d.
This seems to me to show again that having siblings who play is the best way to become very strong.
Rich: As further backup, Nie Weiping is the younger of two go-playing brothers. There was a book published recently that claimed that relative sibling position was one of the most important factors in shaping personality and deciding career; I can imagine that youngest siblings could have the most to prove.
 Bob: John's remarks about youth and the right environment reminded me of a description of conditions in the Kitani dojo. It may have been Kato (if I recall correctly) who said that Kitani did very little explicit teaching. There were a lot of very talented children deshis and all Kitani did was provide the right atmosphere and the deshis became strong.
HandOfPaper: Does anyone know the context of Cho Chikun's remark (the one about hating go)? Without the context, this could be interpreted as a remark he just threw out to antagonize people asking annoying questions.
Quicksilvre: Cho was in Amsterdam to play Game 1 of the 25th Meijin final when the Dutch press asked him why he loved go so much, prompting him to reply, "I hate go." Apparently, his feelings come from the stress Cho puts himself through during games (especially big two-day events).
ilan: Anyway, what does the term "pro" refer to? If it means, "good enough to earn a living at go", then I believe one should include top amateur players who don't have a professional rating. Most of the technical comments given in this page apply to these players as well, since most comments refer to good play.