In respect to rating differences between Karpov and Fischer, I think the argument is using their respective ratings at the time the match would be played, not their peak ratings. According to the January 1975 list, Fischer was at #1 with a 2780 rating and Karpov was at #2 with a 2705 rating. Third was Korchnoi with a 2665 rating. 4-5th place were tied with Tal and Polugaevsky at 2645 ratings. It's worth mentioning that Fischer had been inactive for several years so his rating may not be what it was then, possibly higher or lower. What we can know is that Karpov was clearly the highest rated active player at the time and if ratings mean anything indicate the best chance among the top active players to challenge Fischer with chances to win.
Fischer vs Karpov

It doesn't matter anyway: the Soviets -- I mean FIDE -- anointed Karpov anyway. There's a certain Macbeth quality to it.

It doesn't matter anyway: the Soviets -- I mean FIDE -- anointed Karpov anyway. There's a certain Macbeth quality to it.
Wrong, it does matter. Karpov was declared champion only because Fischer refused to defend his title. This is very clear - by claiming otherwise you are guilty of historical revisionism.
This was Fischer who resigned his title, FIDE didn't strip him of it. They gave into most of Fischers demands, extended the match limit from 24 to a maximum of 36 games and didn't give Fischer essentially a +1 score going into the match. It's hard to feel bad for Fischer really, I feel bad for Karpov and the chess world far more than I do Fischer. Whatever his reasoning for not playing Karpov, he chose not to, and that choice is forever on him and him alone.

Yes and what was the rating gap between Kasparov and Kramnik when Kasparov lost to Kramnik?
Since you're so stupid, I will explain. When you improve, your rating doesn't go up until you play. When you're off form, your rating doesn't go down until you play.
Fischer lost 5 rating points for totally whipping an off form Spassky. His peak rating may have been 2785, but he was not playing at 2780 level against Spassky. He wasn't playing anywhere close to that level.
Karpov wouldn't have been playing chess against Fischer's peak rating but Fischer, who is human and whose actual strength fluctuates more than a rating.

Frankly, Ghostliner, you lack the moral qualification to judge me. Surely, we can disagree while still being civil. I lived through that period of history. I participated in it. I cannot deny my own experience. It would be dishonest.
The USCF blamed itself for Fischer's disappearance, and rightly so. Ask Steve Doyle, if he's still alive. He was president of the USCF at the time. He's a big part of why our letter to Fischer was authorized. If he, as USCF leader, can admit that Fischer was wronged, then will you change your stance? Or will you remain stuck in the concrete of hearsay?

The earlier pages of this thread are interesting, but some of the more recent comments are just wrong.
For the record, Karpov's peak live rating was higher than Fischer's peak live rating (2790.9 vs 2789.7). The difference is meaningless. A match between these two, who at the time of their dominance were the best the world had seen, would have been spectacular.
Yes, Kasparov was marginally but clearly better than Karpov. Their matches were close, but when Kasparov needed to win or draw, he was able to find a way. Kasparov won the matches, 4 wins 0 losses and 1 draw. That's important to remember.
Carlsen is marginally, but clearly better than Kasparov at his best. Kasparov's best rating was 2856 while Carlsen's best is 2889. Even those who argue there has been ratings inflation don't argue there has been more than 30 points inflation from 2000-2014. Carlsen has now won the World Championship and defended it. It's safe to say he's the best ever.
I think that's very dubious. I'm in no mood to spend a lot of time on this, but ELO ratings are always relative to a certain pool of players. Carlsen stands head and shoulders above players now from a peak rating and current rating standpoint, but that does not necessarily imply Kasparov at his peak would be in the same position. All we really know is that in 2000, Kasparov was such and such points above Anand/Kramnik/rest of field and was 2851. Suffice it to say, the pools are not necessarily of the same strength. For instance, would someone reasonably argue that Viswanathan Anand is roughly the same strength now as he was in 2000? After all, his current rating is one point above his 2000 rating, but ratings don't tell nearly the same story.
TL;DR, In my opinion, one cannot use ratings to conclude Carlsen is marginally better than Kasparov at his best. There are better metrics (certainly available for honest perusal anywhere. I don't care to define or find them now) etc.
Not that quoting Wikipedia is the best way to go, but it doesn't sound to me as if the USCF did much to stop Fischer:
"Due to the continued efforts of U.S. Chess Federation officials, a special FIDE Congress was held in March 1975 in Bergen, Netherlands in which it was accepted that the match should be of unlimited duration, but the 9–9 clause was once again rejected, by a narrow margin of 35 votes to 32"
It had been enough if two delegates had voted differently for Karpov to have to score 10-8 to win the title, that's maybe the scariest part of it all, that Fischer's demands were so strongly supported.

Frankly, Ghostliner, you lack the moral qualification to judge me. Surely, we can disagree while still being civil. I lived through that period of history. I participated in it. I cannot deny my own experience. It would be dishonest.
The USCF blamed itself for Fischer's disappearance, and rightly so. Ask Steve Doyle, if he's still alive. He was president of the USCF at the time. He's a big part of why our letter to Fischer was authorized. If he, as USCF leader, can admit that Fischer was wronged, then will you change your stance? Or will you remain stuck in the concrete of hearsay?
Sure we can disagree. I am being civil. I also think your claims are quite wrong and I'm entitled to say so.
There is zero evidence that Fischer was railroaded out of the cycle. He was World Champion, clearly the best player in the world and wasn't the sort of person to be pushed around by anyone. I'm not saying FIDE was perfect (it still isn't now), but implying that they were 'in the pocket' of the Soviets is stretching it a bit. The President of FIDE at the time was Max Euwe, in my opinion you do him a great disservice by implying he acted as some kind of stooge.

You keep missing the point, Ghostliner. The USCF was the stooge.
You're entitled to question my veracity, I suppose, but you do so out of ignorance. Contact Leland Fuerstman through Facebook. He was then and still is president of the Charlotte Chess Club. He and other contemporaries will corroborate my story.

You keep missing the point, Ghostliner. The USCF was the stooge.
You're entitled to question my veracity, I suppose, but you do so out of ignorance. Contact Leland Fuerstman through Facebook. He was then and still is president of the Charlotte Chess Club. He and other contemporaries will corroborate my story.
The USCF was a stooge for whom?
Ok, just for clarity, can you repeat your story please?

First, I'll answer your question, and then I'll tell my story again. The USCF was a stooge for FIDE, which was a stooge for the Soviet Union. Look back at the history, and you'll see that almost every player in contention since its formation was a Soviet. The USSR (Union of Soviet Socialist Republics) included Russia, the Ukraine, all the Baltic states, Poland, Czechoslovakia, and others.
In the early 1980s, we, officers of the NCCA, began formulating a plan to get Fischer to come back to active chess. The wound of his disappearance was still fresh. After working diligently for nearly two years, we came up with a plan that we thought would work.
At that year's conference in Florida, by the USCF Congress, we presented our ideas. There was strenuous debate until a final plan emerged. Be mindful that we had been in constant touch with Claudia Mokarow (Fischer's secretary, who lived in Pasadena), and so I would say that she, too, had a critical role in helping to plan.
At that conference, the USCF finally agreed to send Fischer a letter, offering him a generous salary to do whatever he wished, whether tutoring GMs, giving demos, making appearances -- anything he wished. We would provide him health insurance, housing, transportation, and other support items. We would also declare him to be "The Undefeated World Chess Champion."
For the last item, we had to fight tooth and nail, but we emerged victorious in the end. The USCF would admit that it let Fischer down by not standing beside him. You see, it wasn't Fischer vs Karpov; it was Fischer vs the Soviets. They cheated routinely; for example, they would gather in hotel rooms to review adjourned positions, which was not allowed. There therefore included an apology.
We mailed the letter to Fischer, via Claudia, and waited. After about 6 weeks, we received a plain white post card from her that said simply, "He wants $10,000 to open the letter." By now, Doyle had come in, and he was absolutely livid, screaming that he refused "to shove that much money through a hole to see what happens --- what if he responded wanting more!?"
And so, even though we begged and pleaded, it was no go. For a pithy sum we gave up on our greatest treasure. The USCF had already failed him once, and now here again.
Many years later, as a shell of himself, he played Spassky. Someone with a temperament superior to Doyle's, and not affiliated with the USCF, must have paid him to open a letter.

Incidentally, Fischer's demand was likely a test of the USCF's fidelity. After all, we were promising the moon, and Claudia probably told him so. So why not test their sincerity? in his position, i probably would.

@KantWasWrong:
Thanks for clarifying. The circumstances surrounding that letter and Fischer's demand for $10,000 just to read it are documented elsewhere but you've fleshed it out with some interesting details. I don't dispute your account, which I'm sure is accurate.
However, you've made some other claims on this thread which are highly questionable, and that's being generous. Specifically I'm referring to this:
Frankly, I believe this account not only flies in the face of the historical record, it also requires that we turn logic on its head. The Soviets were desperate to win back the title of World Chess champion and Karpov was their man - why on earth would Karpov "refuse to challenge Fischer" in these circumstances?

Your logic is unsound. Karpov refused to play Fischer because the KGB forced him to refuse, on account of Fischer's demand that Karpov's room be guarded and monitored. Due respect, but you are clearly uninformed about the politics of the time.

Your logic is unsound. Karpov refused to play Fischer because the KGB forced him to refuse, on account of Fischer's demand that Karpov's room be guarded and monitored. Due respect, but you are clearly uninformed about the politics of the time.
Really? And presumably they used their top-secret, "mind control" raygun to coerce Fischer into choosing exile as well. The KGB wasn't the all-powerful monolith you seem to think it was, we know they demanded that Spassky claim the match in Reykjavik after Fischer defaulted game 2 - Spassky refused.
You've been watching too many cold-war thrillers my friend; one doesn't need an elaborate conspiracy theory to explain Fischer's exile, one only has to look at the man himself. It's not possible to overstate the scale of Fischer's achievement: this man took on the entire Soviet chess machine and brought it to its knees and he did it single-handedly, with virtually no help from anyone else.
It was a remarkable and extraordinary feat; but at the end of the day Bobby was a human being just like the rest of us, even before 1972 it was clear that the emotional, nervous and psychological strain of his undertaking was taking a huge toll on him. Once his goal was achieved exile was a natural next step - as Karpov himself has said: "Once Bobby Fischer became World Champion there was nowhere else for him to go."
When asked about his prospects against Fischer at the time (in 1975), Karpov's response was: "I have some chances."
I think it's also worth pointing out that Fischer's attitude towards the Soviet chess community always had two sides. He despised the machine but largely admired and respected the players and was on friendly terms with most of them. He rated Spassky as a player and they became close personal friends, despite the naked hostility between the two respective camps in '72.
Their friendship endured too, one of Fischer's last wishes was that Spassky would act as pall-bearer at his funeral.