How was 'hone in on' bastardised to mean 'home in on'?

It doesn't make "strict logical sense" because honing as originally defined and used has nothing to do with homing. They are neither sharpening something (the first sense) nor perfecting something over a long period of time (a long-established use that started as a figurative use of the original sense).

So if we expected all senses for which words were used to be fully justified by their etymologies, we would be led to reject it in this place.

But note that this argument against hone in is described as "strict". That in itself leans toward not accepting the argument; only someone who was being very strict would insist upon it.

And it's also of the form "while [argument], conclusion". This form is used to concede an opposing point while still concluding otherwise ("while expensive, it's long-lasting and so good value", "while a potential source of jobs, the damage to the environment would be too great" etc.)

Since they've shown how one could reasonably consider this eggcorn as reasonably sensible in its own right (unlike say "play it by year" or "for all intensive purposes") then while they concede that point, on balance they consider it reasonable.

"Hone in" is usually referred to as an "eggcorn", which is a mis-rendering based on mishearing the original expression. There are dozens, if not hundreds, of these. They are frequently discussed by the American Dialect Society: http://www.americandialect.org/publications/ads-l-the-american-dialect-society-email-discussion-list

I recently was surprised to read a variation -- "hone onto" -- used by a professional writer whom I would have expected to know better. It made me suspect that an increasing number of people are becoming unfamiliar with the older meaning of "hone".

This might be related to an increasing trend toward "information work" and away from the use of physical tools, and the increasing number of things with "no user serviceable parts inside". (Vernor Vinge wrote about this in "Rainbows End", for example.) Thus we more have people don't know the names of various tools, or indeed what a hone is, how to use one, or what "to hone" used to mean.

Etymology is nominally the study of trends in word usage and meaning, which in turn is closely tied to cultural changes. I'm not sure whether analysis like the above is etymology per se, but I would think if you were seriously studying the etymology of words, you should probably look to their foundations.

Christine Ammer, The American Heritage Dictionary of Idioms, second edition (2013) offers the following discussion of "home in on":

home in on Move toward or focus on a goal, as in He began with a couple of jokes before homing in on the main subject of his talk. This expression originally alluded to a vessel, aircraft or missile being guided to its target by a radio beam or some other means. {c. 1920}

Ammer doesn't mention "hone in on"—presumably because she views it as being either a minor variant or an error.

Webster's Dictionary of English Usage: English Dictionary (1989) has a lengthy entry for "hone in on," anticipating that the phrase might someday become sufficiently widespread that dictionaries would include entries for it and usage commentators everywhere would decry its rising popularity—all of which have indeed come to pass. Here is the WDEU entry for "hone in on":

hone in on An issue looming on the usage horizon is the propriety of the phrase hone in on. George Bush’s use of the phrase of this phrase in the 1980 presidential campaign (he talked of "honing in on the issues") caught the critical eye of political columnist Mary McGrory, and her comments on it were noted, approved, and expanded by William Safire. Safire observed that hone in on is a confused variant of home in on, and there seems to be little doubt that he was right. Home in on is a fairly new phrase itself, one whose origins can be traced to the verb home as it relates to homing pigeons. The OED shows that home was first used in the sense "to fly back home after being released at a distant point" in the late 19th century. ... Our first example of home in on is from 1951, in a context having to do with aviation. Our earliest record of its figurative use in a general context is from 1956. We did not encounter hone in on until George Bush used it in 1980, but we did record two instances of hone in in the '60s:

...looking back for the ball honing in to intercept his line of flight —George Plimpton, Paper Lion, 1965

Wallace has been able to "hone in some basic issues ...," Bush said —Houston Post, 14 July 1968

George Bush again? Probably so. He was a congressman from Houston in 1968.

The George Bush in question is George H.W. Bush—the forty-first U.S. president, and father of the forty-third president.

The early days of 'home in on'

As WDEU observes, the expression "home in on" isn't exactly ancient. The earliest match for the verb phrase "home in" that an Elephind search finds is from 1917 and involves pigeons. From "Homing" in the [Perth, Western Australia] West Australian (October 13, 1917):

The West Australian Homing Association flew their race last week from Rawilinna, on the trans-Australian railway line, a distance (air line) to Perth of 555 miles. The birds had to fly against a north wind, and not one homed on the day of liberation, but arrived next day, with the following results:-S. Dower (Mount Lawley), blue c h, 870yds. per minute; 1; T. Birchnell (Swan View), blue c h, 863yds. per minute, 2; W. Joss (Perth), red c h, 856yds. per minute, 3. Also homed in on the same day, W. Ferguson, W. Hardy.

This instance actually includes the full character string "home in on," but the "on" introduces a prepositional phrase introducing a time frame ("on the same day"), not a target of the homing in. Earlier instances of "home" without "in" appear decades earlier in connection with pigeon racing—as WDEU notes. For example, from "Sydney Homing Pigeon Society" in the Sydney [New South Wales] Morning Herald (May 30, 1883):

The birds were liberated at intervals of 10 minutes, commencing at 10 a.m., the weather being then fine and clear; but unfortunately for those liberated after the first hour the wind had risen; bringing with it a heavy shower of rain, notwithstanding which they homed in good style. The result was as follows:-1, Haymarket's A, 90½ minutes; 2, Slowgrove's G. B. D., 88 minutes; 3, Haymarket's C, 100 minutes. From the above it will be seen that Mr. Slowgrove's bird homed in less time than Mr. Haymarket's, but as the loft of the former is about 3 miles nearer Moss Vale than the latter's, the usual allowance of 1½ minute per mile was added.

The earliest instance of the phrase "homed in on [a target]" that Elephind produces involves not birds but resentful human hosts. From "The Gentle Grafter," in the Edgefield [South Carolina] Advertiser (July 13, 1921):

“It is no secret to the people who come and camp on us that Jim and I are a poor couple struggling to get a start in the world, and that every dollar counts with us. Also they perceive that I do my housework, and that by homing in on us they add immeasurably to my labor and the expense of our living.

"But does that keep them away?" It does not.

This instance is unique among the matches I examined, however. An example more typical of the now-popular sense of "home in on" as "identify and move toward [a target]" appears in "Helps Planes from Ascension Base," in the Irvington [New York] Gazette (August 17, 1944):

"I remember after one C-46 crew went into the drink it took us two days to find the survivors. They had gotten away from their wrecked plane safely and had sent out a signal on their life raft’s emergency radio.

"We were homing in on them soon after they were forced down but lost the signal. We learned later that a transient plane had buzzed the raft to see what it was and had knocked down the aerial which had been flying from a kite.

This example is seven years older than the WDEU's earliest instance, but it, too, involves aviation. An early figurative use of the phrase appears in a panel of the comic strip "Terry and the Pirates" in the San Bernardino [California] Sun (March 18, 1951), in which Terry is shown speaking outside a door marked “Commanding General":

"Must be a rumble on. Lots of big bass homing in on the old man's office."

'Hone in on' horns in on the proceedings

I discovered two odd and unexpected things about the earliest instances of "hone in on": first, they are roughly as old as the first instances of "home in on" (slightly older, actually); and second, they seem to involve garbling not of "home in on" but of "horn on on." From a diary entry written at Gengoult, Toul, France, dated May 5, 1918, in "Philip Washburn Davis," in Memoirs of the Harvard Dead in the War Against Germany, volume 3 (1922):

I got in back of the second plane and pulled up near and saw the French cocardes on the wings, so flew over it and to the right to join Jim who was way out in front. What was my surprise to see him attacking the other machine. "The darn fool is attacking a French plane," I said to myself. Just then the plan went into a vrille, a very slow one, too, which gave me time to pull up on him, and sure enough I saw the German insignia on the black wings, not even crosses but a white diamond with perhaps a little cross in the middle. As the Boche came out of the vrille, Jim shot again. The Boche piqued, smoke came out at the left and then flames. As Jim dove under I piqued on the Boche but didn't fire, as I figured he was finished anyway and I didn’t want to hone in on Jim's credit. I pulled up and saw Jim come around and give the Boche another round. He was taking no chances on his first Boche. After that the Boche was falling pretty fast. I went through a lot of burned wing cloth and leveled out at about 3000 metres. I saw Jim going off toward France but stayed around a little while to see the Boche crash in a wood in the German lines.

The writer of this diary entry was a 30-year-old native of Massachusetts, a Harvard graduate, and a member of the "Lafayette Flying Corps" of U.S. aviators in World War I. By "hone in on," he doesn't mean "zoom toward [a target]"; he means "intrude upon."

Likewise, from Peter Manton, "Mystery at Mamby House," in the [Rockhampton, Queensland] Morning Bulletin (February 26, 1940)

"You're well-informed, my friend."

Pike grinned, baring his teeth again.

"I have to be. And you're the nephew of Sir Nicholas, naturally bursting to hone in on this affair, for family honour. And what have you?" Pike poised a fragile lump of fried turbot on his fork. "Boloney. Forget it. Go and do some more hunting, Arden. It's safer, and you'll be more use there, anyway. And listen, buddy, don't start getting hot under the collar, eat your breakfast and think straight." He was talking evenly, and without the slightest embarrassment. "I know this game, and I'm telling you what's good for you."

Here again, the evident sense of the expression "hone in on" is "butt in," not "zero in." And from Meridel Le Sueur, "O Prairie Girl: Be Lonely" (written in the 1930s but not published until 1945):

Surprise, that's his racket, that's the thing Hitler's got, surprises . . . the poor rubes don't know what's up and don't believe any thing's going to happen and before they know it he's over the hurdles with the dough in his jeans pretty as a picture.

Yeah, Hone says, that baby's smart.

Plenty, Ganz says. I'd like to hone in on his racket. What we need in this country is somebody like Hitler, that's what we need. Hitler knows we don't need so many people, kill off half of 'em, leave only the best people who know what it's all about.

Here the fact that a character named Ganz uses the expression "hone in on" in a conversation with a character named Hone is certainly odd—but I don't think that Ganz is alluding to his interlocutor's name (for one thing, Meridel Le Sueur is all about no-nonsense socialist realism, not wordplay).

The earliest instance I found of "hone in on" in a place where "home in on" (as opposed to "horn in on") would make more logical sense appears in testimony of February 18, 1948, before the House Committee on Foreign Affairs, in Foreign Assistance Act of 1948:

Mrs. [Frances] BOLTON [of Ohio]: I am in complete agreement with Mr. Mundt as to this financial end of it, but what we have agreed to do is consider a foreign policy. Now that involves any number of things, and the people of this country want us to hone in on what the foreign policy is going to be. They want us to be intelligent about it.

This instance, like any other discrete instance of "hone in on" in print, might reflect a typographical error. After all, the N key on a typewriter's keyboard is right next to the M key. But it seems equally likely to me that even these earliest occurrences of "hone in on" in print are intentional and accurate representations of the speaker's or writer's word choice. Following are a number of additional instances of "hone in on" from before 1980 (the year of WDEU's oldest instance of the phrase). From a sports headline in a college newspaper, the Daily Kent [Ohio] Stater (October 18, 1960):

'Bombers' Hone in On Target

From "All-America Honors Beckon," in another college newspaper, the [University Park, Pennsylvania] Daily Collegian (May 23, 1968):

There may be some truth to the rumor that the Creator chiseled out McGuone specifically for goal tending of one form or another. His junior high days were spent diving for loose balls on the soccer field and it was just natural that he should have honed in on the nets when he took up lacrosse in his freshman year at Sewanhaka High School on Long Island.

From "Quarterfinals at Wimbledon," in the [Palm Springs] Desert Sun (June 25, 1971)

WIMBLEDON, England (UPl)—The money players hone in on each other today.

At stake: the quarterfinals of the 85th Wimbledon Tennis | Championships — the world’s toughest and most prestigious tennis event.

From Elizabeth Gilliland, "Hitler's Sleepwalk & the German Renaissance," in the Columbia [University, New York City] Daily Spectator (November 2, 1972):

Friedrich's meeting with Rudolf Serkin is over cold cuts:

Rodolf Serkin has an invisible keyboard that is always before him. Sitting in a restaurant, or even walking along Rittenhouse Square in Philadelphia, he is apt to illustrate a point by holding forth his arms and letting the fingers flicker over the keyboard. The piano is not just his profession but his life.

This illustrates Friedrich's mastery at honing in on salient features of the personalities he interviews or knows of, from musicians to Nazi leaders.

From "Duet Aids in Rescue from Sub" in the [Palm Springs] Desert Sun (September 23, 1973):

CORK, Ireland (UPI) - The sound of sea chants floated from the tiny submarine lying crippled at the bottom of the Atlantic.

Inside, Roger Chapman, a bathtub baritone at home, and Roger Mallinson, observing his 35th birthday, were singing for their lives at the top of their lungs.

The duet enabled rescue subs to "hone in" on their voices through the ocean bottom's inky blackness and locate the position of the two Britons, whose disabled craft was brought to the surface Saturday in history’s deepest sea rescue.

From "Procession Puts Parents in a Tizzy," in yet another college newspaper, the Stanford [California] Daily (June 21, 1977)

Less analytical spectators were settling for photographs. Movie cameras whirred, shutters clicked, and telephoto lenses honed in on one particular cap and gown.

From James Wise, "Creating the Future of Impact Management," in Recreational Impact on Wildlands: Conference Proceedings: October 27–29, 1978 (1979):

"If the manager says, there's a problem up on the hill, go and do some research on it, he's going to probably get something fascinating and esoteric, but maybe not very useful. He has to be very specific of what the requirements are, and only then can the researcher hone in on a particular problem and the results will be much more applicable, more easily interpreted." That is, if the problem (or the manager) is still around when the research is finished.

Although most of these instances of "hone in on" in the sense of "home in on" are from college newspapers, they are probably responsible for a much smaller proportion of such instances overall. U.S. newspaper databases are skewed heavily in favor of college newspapers and small independent newspapers from the mid-1920s onward because copyright restrictions on the material they may disclose to the public. I have no doubt that many additional instances of "hone in on" exist in major metropolitan daily newspapers that Elephind and Chronicling America are not permitted to search.

What about 'horn in on'?

Christine Ammer, The American Heritage Dictionary of Idioms, second edition (2013) has this entry "for horn in on":

horn in on Intrude, join without being invited. For example, She has a rude way of horning in on our conversations. This expression alludes to an ox or bull pushing in with its horns. {c. 1900}

If the "circa 1900" origin of "horn in on" is accurate, the expression isn't much older than "home in on" (by 1921) or "hone in on" (by 1918). In fact, the earliest Elephind match is from William Slattery, "Rumor Says Bat Nelson Has Called McFarland Match Off" in the San Francisco [California] Call (April 29, 1909):

Well, boys! There's another bid for the Jeffries-Johnson match on now. Guess where its from this time? Why Goldfield, of course. Nobody ever has a chance to stop Goldfleld when that busy mining town sees a show to horn in on anything that looks big. It's a sort of Johnny on the spot place, and it always has a live press agent on its staff.

And a couple of years later, from "Bob Thayer's Sporting Gossip," in the Washington [D.C.] Times (October 21, 1911):

Governor Austin Crothers of Maryland and John E. George, organizer of some of the fastest amateur teams Maryland has ever known, together with Connie Mack and Johnny McGraw, will be special guests. I don't belong in Maryland, but I wish I did, bo that I could horn in on this dinner. It'll be held at the Walton in Philadelphia some time next week and should be a rouser.

But even in the world of "horn in on" the idiom does not always run smooth. Consider this instance from "Fertile Ground: Sowing the Seed Which Flourisheth" in the Port Macqaurie [New South Wales] News (January 21, 1933):

Do you know that before I found my right vocation in life I tried my hand at twenty-seven different kinds of job? And that's no record on our side of the Pond. I sold papers on the sidewalks of New York. I was bell-boy in a big hotel on Farm-street in San Francisco. I shone shoes in Chicago. I did twenty odd -other things before I horned in on my true metier in life. And that was candy. Berger's Candy. Why is Berger's Candy like the British Empire? Because the sun never sets on it.

It's hard to see how a person could "intrude without being invited" on one's own metier. Far more reasonable is the idea that one might "move toward or focus on" one's eventual metier "as a goal." But that's the definition of "home in on," not "horn in on."

At first blush, it may seem odd that people might confuse "horn in on" and "home in on," but it's not hard to find examples where either term would suit a particular situation. Consider this instance from "Bluffs: How They Live and Thrive in New York," in the Bismarck [North Dakota] Daily Tribune (July 12, 1914):

Doubtless you have met, in the course of your journeyings, the flash diner out.

There are several varieties of this species of bluff, diverging all the way from the harmless frequenters of garish restaurants, where the food is too highly spiced and the music too loud, to the more menacing kind that stand about in exclusive palaces of pleasure waiting to horn in on anything from a sup of tea to a partridge and truffle dinner.

The notion of freeloading "flash diners" waiting to pounce on an acquaintance in order to cadge a free meal certainly fits the notion of "horn in on"—but it works quite well with "home in on," too. And any time two similar phrases make sense in the same context, the likelihood that one may become confused with the other increases.

In fact, some evidence suggests that "horn in on" may have originally meant "freeload." Consider the cartoon "Horning in on the Firm's Lawyer," in the El Paso [Texas] Herald (April 18, 1918), subtitled "Indoor Sports: Watching the Office Egg as He Spiels to the Sec. of the Firm's Lawyer Trying to Get a Case Settled Without Cost." The point isn't that the "egg" is intruding on the lawyer—the secretary says that the lawyer "isn't in at the present moment"—but that he is trying to get legal counsel for free; other employees note that the "egg" also "uses all our stamps" and "never phones unless its from here."

This sense of "horn in on" is much like the one suggested in the Bismarck Daily Tribune instance noted above. It even works in the 1918 "hone in on" example by the Harvard fighter pilot, who might be saying not that he didn't want to intrude on a fellow pilot's triumph but that he didn't want to steal credit for the "kill"—that is, to claim responsibility for downing a plane after someone else had done the hard part.

Other senses of "horn in on" also appear in early examples. For instance, from F.S. Hunter, "For the Sheriff Comes Tomorrow," in the Omaha [Nebraska] Daily Bee (September 6, 1914):

Not that we wish to horn in on the cost of living, but we remember some time ago a few persons in Washington were talking about free sugar. You know what it costs now.

The sense of the expression "horn in on" here seems to be something like "bring up for consideration." Still "intrude" as a possible meaning of "horn in on" exists from the matches onward.

Conclusions

"Home in on," "hone in on," and "horn in on" all debut in book and newspaper databases in the first quarter of the twentieth century. Today, "horn in on" is distinct from the other two, with the specific meaning "intrude without invitation"; and "home in on" has a long pedigree (originating in pigeon racing) of meaning "target," while "hone in on" strikes most people as being a Johnny come lately to the party that offers only a weak (and not especially logical) echo of "home in on."

A look at the history of the three phrases, however, suggests that speakers and writers have used all three far less rigidly than most people today imagine. In fact, overlapping usage and shifting senses have been features of popular usage of the three phrases during much of their existence.