Why is it called "to not pull any punches" and how did this phrase originate?

If one does not pull any punches, he speaks bluntly.

Why is this idiom phrased this way?

Is it because the motion of a punch, i.e., to speak bluntly, can be described as a push, which is the opposite of a pull, and thus to pull a punch would be to minimize the impact of the punch, i.e., to not speak bluntly?

What is the origination of this phrase?

Solution 1:

From Christine Ammer, The American Heritage Dictionary of Idioms (1994):

pull no punches Behave unrestrainedly, hold nothing back, as in The doctor pulled no punches but told us the whole truth. This expression comes from boxing, where to pull one's punches means "to hit less hard than one can." This idiom, too, has been applied more generally, as in They decided to pull their punches during these delicate negotiations. {First half of the 1900s.}

From Robert Chapman & Barbara Kipfer, Dictionary of American Slang (1995):

pull one's punches v phr prizefighting by 1934 To soften one's blows; be lenient and moderate [example omitted].

I found instances of the idiom going back to 1915 (in Google Books search results) and to 1909 (in Library of Congress Chronicling America search results), but the sense of "pulling" as meaning "holding back from throwing (a punch) at full force" is already in place in those earliest examples.

Early Google Books matches

The earliest match for an allied phrase in Google Books search results is from Charles Van Loan, “Too Much Pepper,” in Everybody’s Magazine (June 1915):

Duffy had one great advantage: he didn't have to pull any punches to keep from hurting a friend [because no one in the melee was a friend of his]. Everything that landed was so much velvet. They [his six adversaries] finally got him out [of the room], of course, but every one of 'em had some sort of a receipt for the transfer and the room looked as if it had been struck by forked lightning. It’s no easy matter to put a strong man on the other side of a door if he’d rather not go. Duffy took some of the furniture with him when he finally landed out in the hall. Bentley and Petersen had three black eyes between ’em, McGrath had a split lip, Price’s nose was mashed, and Morton and Harlow were bruised in the shins where Duffy had kicked ’em.

From H. C. Witwer, “Your Girl and Mine,” in The American Magazine (September 1917):

”Listen!” I says, in answer to his proposition. “How would a worm like to hear that fishin’ had been barred all over the world? What am I supposed to do for this, blow up a bridge?”

Neither!” he smiles. “You’ll be my personal attendant and trainer. I want some big husky like yourself to get me in shape for these pictures. I want a man who can teach me boxing, wrestling, how to take punishment, and exercise that will put muscle in me and toughen me up so that when Desperate Dan throws me over a cliff in the third reel I won’t have to spend the following month in a ward. So I want a trainer. I yearn to be toughened up. You can go as far as you like, and you won’t have to pull any punches on me when we begin training. I won’t, I assure you! I expect to get beaten up the first few times, so have no qualms. Now what do you say?”

The first matches for the phrase “pulled his punches” is from Frank Condon, “Punch and Julie,” in Collier’s (August 6, 1921):

The general and justifiable complaint had been that in his [filmed] fight scenes Hugh Foley pulled his punches. His fights, said the critics and the public, were fake brawls and devoid of sincerity. Instead of knocking the loathsome villain for a couple of goals, Hughie hit him softly and tenderly, pretending a vast amount of violence but deluding nobody. Least of all did these bogus battles deceive the lynx-eyed gentry that walk in and sit down after paying their two bits to the cashier.

From William Hamilton, The Stock Market Barometer (1922):

Knowing and liking [Charles H.] Dow, with whom I worked in the last years of his life, I was often, with many of his friends, exasperated by his overconservatism. It showed itself particularly in his editorials in the Wall Street Journal, to which it is now necessary to allude because they are the only written record of Dow’s theory of the price movement. He would write a strong, readable and convincing editorial, on a public question affecting finance and business, and in the last paragraph would add safeguards and saving clauses which not merely took the sting out of it but took the “wallop” out of it. In the language of the prize ring, he pulled his punches.

From Everybody’s Magazine, volume 49 (1923) [combined snippets]:

”Do you know what it’s like to battle with two busted hands, Mr. Overton? I can tell you it’s hell! Is there any other fighter, alive or dead, what wouldn't have pulled his punches with two busted hands? Is there any other fighter that could have helped pullin' his punches? Now, I'm askin' you, Mr. Overton!”

The first five instances of "pulling punches" work out this way: one unrefereed melee, one proposed training regimen, one instance of fake fighting for a film, one metaphorical use of "pulling punches" in connection with editorial writing, and one instance of a boxing match in which a fighter's hands were "busted." Somewhat surprisingly, not one of these instances involves throwing a prize fight. In any case, the reasons why a person might legitimately want to pull punches (actually or metaphorically) are more numerous than you might initially expect.

Earlier newspaper use of the term

The Library of Congress’s database of historical U.S. newspapers turns up some even earlier instances of pulling punches, going back to early 1909. One of the earliest instances is from “James M’Sherry Makes Debut as Coming Champion,” in the [New York] Evening World (January 16, 1909):

”This boy can be developed into a great fighter,” said Johnny White. “He could enter the ring today and beat all the Burkes and Thomases in the game. He is a fighter of Ketchel’s style, and will soon be able to give Ketchel an argument. The chief fault with him is that he has been teaching boxing so long and pulling his punches that he is afraid to let them go. …”

MacSherry was the boxing instructor at Yale. An article in the Salt Lake [City] Herald (February 19, 1909) offers the provocative headline “Teachers Make Poor Fighters: Boxing Instructor Seem Unable to Deliver a Strong Punch” and then quotes the [New York] Evening World at some length on the problem of pulling punches:

Unfortunately, a boxing instructor can’t cut loose and hit hard. He’d lose too many pupils if he handed out black eyes. So, as a general rule, men who teach boxing for any length of time forget how to hit hard. And that’s a knack that I very elusive when once lost. Tommy West, one of the toughest fighters of ten years ago, once started a boxing school and taught for several months. When he began fighting again he found that he couldn’t help pulling his punches. So he got together a training staff of sluggers and fought them as hard as he knew how for a month. In course of time he regained his wallop. But Tommy told me he’d never teach another pupil until he retired from the ring for good.

From Max Balthasar, “Papke Is Out of the Ring Now,” in the Salem [Oregon] Capital Journal (May 20, 1910):

Papke’s work, or rather, lack of work, was the worst ever seen in a local [San Francisco] ring, and although many fakes have been pulled off here, his has all the others beaten by a mile. That Thomas was not a party to the job is plain, as the Californian, 15 pounds lighter than his opponent, entirely devoid of the dash he showed in training and scared half to death, really tried his best, but that is not saying much.

The go had hardly passed the fifth session when it was plain to everybody in the house, with the exception of Referee Jack Welch, that Papke was not trying, that he was pulling his punches, purposely missing, and hugging at every opportunity. Time after time Thomas left openings as wide as a barn door and instead of taking advantage of them Papke would make a fake lead, miss and fall into a clinch. Occasionally he fought viciously—with his face—assuming a bull dog expression with which he hoped to bull the spectators into the belief that he was going to do something real saucy, but then he would refuse.

When the seventh round opened the house resounded with boohs, cries of “fake,” “throw them out,” “cal lall [call all] bets off” and “rotetn [rotten].”

This last account is especially interesting because it describes "pulling punches" in the context of a fixed fight—and the crowd's reaction to it.

Solution 2:

You punch away from you; you pull toward you. So to pull a punch is to pull back the blow toward you and away from your opponent.

A boxer would pull a punch against a sparring partner or to throw a fight against a real opponent (that is, to intentionally lose to that opponent).