Paul Morphy's Rating>2638

The theory is that Paul Morphy's fide rating in today’s standards, if he happened to come from the grave and played as well as he was in his prime from the 1800s, would be about 2638. While this is not world champion level, he would still be considered a strong grandmaster. This conclusion came about by looking at Morphy's match and tournament scores of his games that were not played at odds or other handicaps. Only opponents that Morphy played a substantial amount of games against, at least 12, were used in order to increase the accuracy of the conclusions. This precaution factors in the idea that chess players often have 'bad days', and with all the traveling players did back then they were often sick for the first few games in a match.

Morphy’s record against Eugene Rousseau in match play was 45/50; which would make his rating at least 358 points higher than Rousseau.

Against Louis Paulsen in tournament and match play, his record was 9.5/12; making his rating at least 226 points higher than Paulsen.

Against George Hammond in a match, Mophy scored 15/16; making his rating at least 412 points higher than Hammond.

Against John William Schulten in a match, Morphy scored 23/24; making his rating at least 457 points higher than Schulten

Against Henry Edward Bird in a match, Morphy scored 10.5/12; making his rating at least 320 points higher than Bird.

Morphy scored 14/17 in matches against Adolf Anderson; making Morphy at least 257 points higher than Anderson.

This astounding record is 117/131, 89%.

All of the players listed were strong and considered some of the best masters of their day.

It can be estimated that this lot of masters today would have an average fide rating of today’s standards of at the 'very least' 2300. So 2300+338=2638, 338 is the average amount of points Morphy scored higher than his "rivals" in the previous part of this text.  It should be noted that Adolf Anderson in particular was 'estimated' to be over 2600 by Aprad Elo (the inventor of the rating system in the first place). One should also note that Aprad Elo himself believed Morphy was 2690.

On top of this evidence, it is said that Morphy often played 8 blindfold games at a time while still managing to win the great majority of the games. I asked one of my friends who is a Grandmaster, 2496 at the moment, how many blindfold games he could play while still keeping most of his strength, and he replied that he was sure he could play 3 at the same time and maybe a 4th without over exerting himself. Morphy being able to easily play twice as many blindfold games further proves that he was not just any 'weak grandmaster, strong international master level', and that he could in fact be a strong 2600 rated Grandmaster.

The idea of how much rating points Morphy was higher than his opponents was calculated by plugging in his win percentage into the chart that corresponds with elo ratings at  https://www.chessville.com/Reference_Center/WinPercentageExpectancies.htm

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The match and tournament results of Morphy are from

1.  ^ Edo Historical Chess Ratings – Morphy, Paul

2.  ^ Jeremy Spinrad, Collected results 1836–1863

3.  ^ C. Sericano, I grandi matches 1850–1864

which are summarized in https://en.wikipedia.org/wiki/Paul_Morphy .

I think this is a solid guess.  I forgot what rating chessmetrics (similar to what you just now did but ridiculously in depth) put Morphy at but I think it was around that.

Adolf Anderson, Louis Paulson, & Henry Bird all would have been rated higher thatn 2300, enough so - IMHO - that your average of 2300 is waaaay too low.  I think you need more empirical evidence than just your supposition.

The Chessmetrics site estimates (scientifically) that Morphy's peak rating would have been 2743.  Other peak ratings from your list above:

Anderssen = 2744
Bird = 2635
Hammond = not given
Paulson = 2710
Schutten = not given

I think the chessmetric ratings are just used to determine the dominance of a player in his time, and that we can compare this dominance from era to era?

It's not strength per se that is being measured.

We'll also find that the ratings are not equivalent to FIDE ratings, if we just look at the numbers for modern players whose ratings we are well aware of.

For the record chessmetrics ratings are only meant to compare players of the same time period and thus are highly inaccurate for comparing players of different periods.

That is definetely incorrect. With the rating difference of 338 (as in your formula), he would have been expected to score 88 points out of 100 against other masters. Of course, he didn't. Another approach is to actually look at the games (and it quickly becomes obvious that he was nowhere around 2638 strength).

Chessmetrics doesn't take into account the different standard practices of the 19th century,  or, more precisely, it treats 19th century player the same as modern players, which tends to ignore many of the things that not only made the 19th century more charming but actually defined many players' relative skill - the very measuring tool, I would imagine of retro-rating. While I'm by no means a statician, I am firmly in EDO chess'  retro-rating camp particularly when it comes to pre-20th century players (EDO only rates players up to the year 1900). see: http://www.edochess.ca/Edo.explanation.html to help understand the differences in systems.

Appropos to this discussion, you might read down on the link provided above to a section called "Results (updated 2010)" in which Morphy is talked about in some detail. Rod Edwards explains why Morphy is assigned a peak rating of 2821. 

I think I remember seeing an estimate of 2680-90 somewhere, but that seems too low.  I'd hazard a guess around 2730s today accounting for inflation.  If he got up to date with theory he'd be even higher.

Morphy may have played at 2600 strength in the openings that were popular in his day, the King's Gambit, Giuoco Piano, Evans Gambit etc. But if he played against modern GMs he would likely never even get any of these openings on the board. It's a bit like saying that Newton was on the level of a modern physicist based on his accounts of Newtonian physics while today's field is much broader.

 As stated in the original post he in fact did score about 88/100.  It should be noted many of Morphy's 'blunders' were made on purpose in attempts on his part to finish the game faster, as stronger players often do against much weaker opposition. 

I agree with NM tonydal. You can't possibly compare players of different times. You can only compare them relative to their contemporaries. And it gets paricularly difficult in comparing 19th and 20th or 21st century players. 19th century players often rated themselves through piece odds (there was no real chess clock until the latter part of the century, so even time odds wasn't possible) and these games were perfectly valid though, in truth, they required a different skill set, casual games were usually treated as seriously as match games  (there were few tournaments until the last quarter of the century).  Players were generally amateurs who devoted relatively little time to the game (compared to professionals of today). There was no real chess instruction, few books (and books were expensive) or public libraries, no databases other than what was in the books few people had or in magazine.

It was indeed a very different world back then.

John William Schutten

Just for the record: John William Schulten

It's like saying Napoleon sucks as a general because he didn't know how to deploy nuclear weapons.  If you took a modern grandmaster and magically erased from his knowldege,  all the advances in chess since 1850, and made him play against Morphy in a match without seconds; I think most mordern grandmasters would be in deep trouble.

For some reason the OP left out a match that ought to have been included: Morphy-Harrwitz 5.5-2.5.

If Morphy came back from his grave playing like he did in the 1800s his rating would be 2100 at the most

I left this match out as Morphy was sick for the first part (which he lost 2 games).  Also if I included smaller matches like this I would also need to include many more games where he completley demolished his opponents.    

Yes, Morphy was having a bad day actually.

Harrwitz was arguably stronger than Anderssen at that time, making his omission somewhat spectacular.

Morphy was a notoriously bad traveller and yet he insisted on playing after the channel journey. He started poorly, Harrwitz was obnoxious, Morphy proceeded to roll him, Harrwitz then excused himself from the remainder of the match on a health excuse.

Harrwitz was nevertheless a wonderful player.

Well, that is your opinion. It is far from clear what it means to assign ratings to players who played before ratings even existed, and when competitive chess was in the cradle. 

Well, people tend to mix two notions:

1) Relative achievements - Morphy was #1 at his time, that says it all. Ratings are just a way of showing who the #1, 2 and so one are.

2) Objective achievements - the topic-starter seemed to believe that Morphy had the chess skills of a 2638 of year 2010. That's a dubious estimate. Saying so is not an attempt to deprive Morphy of greatness, but simply being fair in evaluating his playing strength. By modern standards, Morphy is a conservative master (with no opening & endgame knowledge), but rather good practical skills. My guess is that it corresponds to something in the IM - weak GM range. Not a 2600+ GM for sure. Those are not inferior to him in tactics, but definitely have a better understanding of opening, middlegame plans, endings. FMs and below can't boast an overwhelming theoretical advantage compared to him, but are definetely inferior in calculation and understanding. So he should have scored over 50 percent against them.