some of my favourite authors are self published Some of them show just how bonkers the modern publishing industry is. Their works are quirky, original and innovative. They remained unpublished because they are too long, too short, too gay, too whatever else the publishing industry objects to at the time. There is a lot to be said for a story where the author has employed the editor and retained creative control. I'm not with a publisher only been writing two years and have yet to be offered something I would be happy with. For some characters a name change isn't a problem, but for others it can be a major character issue. For example my character Socrates if a publisher changes his name it messes up the entire series of books as he becomes the Greek philosopher and Plato's mentor in a later story. (It is based on the idea that the only evidence of Socrates existence is Plato's plays). The names I've chosen in my fantasy are often relevant to the character in some way and changing it would be as devestating to the story as making characters more straight or changing the time it is set in. Michael Morpurgo whilst writing often calls his MC Michael and then changes it later. There is nothing wrong with it, and certainly hasn't destroyed his career.
Ok, as a premise for a story you can take that as true, but just to disabuse you of a misconception... it's not true. The historical Socrates is referred to in far more contemporary sources then just Plato's dialogues (Xenophon, Aristophanes, etc). He served as a hoplite in the Peloponnesian war, saved the life of Alkibiades at the battle of Potidea, and was executed by the Athenian authorities for corrupting the youth and bringing the gods into disrepute. I'm sure you know this, but I write for the benefit of anyone else who might be tempted to believe your fictional premise If it was really important to the characterisation or plot (as opposed to you just thinking it's important because of your authorial bias), I can't see a publisher asking you to change it. They're not THAT dumb...
I know his story and have the bases covered, it's a time travel it was based on an idea put forward by a history professor years ago that Socrates could have been a fictional character cooked up by those who wrote about him as a teaching tool, so that they could commit the offence of sophistry indirectly. However that only becomes an issue in book five, so a publisher may not allow that to be taken into account on a two/three book deal. I've seen publisher's editors make dumber decisions in the past ten months with books I have beta-read for others.
It's an interesting theory, but hardly new - it's done the rounds a few times, but is essentially both irrefutable and unprovable. However, I find the idea that 3 separate writers of very different literary genres (philosophy, history, comedy) would have made up a character with the same name to express their respective views. I find it far more plausbile that they each used a real historical figure and each interpreted him in their own way. And besides, Aristophanes was famous for poking fun at prominent Athenian citizens - that's the whole point of satire! If the character of Socrates in the Clouds wasn't based on a real person, where's the funny? Ok, before Cogito comes over here with a big stick and his 'OFF TOPIC!' face on, I'll try to steer this back to the OP's question... I'd keep the name as it is for now. Write it the way you want to, and only worry about the little details if and when you submit it to an agent. They may say change it, they may not. If they advise you to change it, you may just respond by chanigng agents (although I wouldn't advise this, as getting accepted by an agent is about as likely as winning the lottery these days, so being able t get another one is not a given).
It would bother me a bit. I suppose it's just one of those things that makes the reader stop for a moment too long to wonder about the real-life circumstances surrounding the author's choice of name. In my opinion, anything that makes the reader stop and wonder about the author's motives instead of the character's motives is an unnecessary speed bump. My MC lives many of the experiences I've had in my own life and my novel itself is somewhat semi autobiographical. For my own comfort, I've kept my female MC's name the same amount of syllables as my own. I've also had her name end in an "i" as mine does, but this is because her love interest has a weird way of pronouncing her name (as he did in real life) that just wouldn't be the same without the "i" That's as far as I take it though.
I'm merely exploiting it for a couple of stories and adding a twist, along with Lewis Carroll's migraines and missing diaries. I'm not sure I believe the idea that Socrates was a fictional character used as a shield by intellectuals to keep themselves alive, but I loved the idea and story. I've just written around 20 stories based on my favourite historical what ifs (one being a made up one pertaining to the world). A publisher is unlikely to care about a second series based on a minor character in a first novel, but I do. Fact remains if they start calling him Bob, Jack or Blah in the first story which it won't effect, it messes up several stories. Satire can be funny based on fictional people Alan B'stard, Jim Hacker etc come to mind - they are caricatures of real people. My real name has literary significance so it was fun to use the surname for a certain character and my first name for another. Like using Emma as my matchmaker or Uncle Tom as the servile, downtrodden twin brother. The homage is to previous writers rather than myself, kind of like Thomas Hardy did with his stories and Dickens sometimes. Jane Austen had a limited collection of names based on those around her (Including Jane Bennett).
It really depends on the name... while Johnson might be acceptable, something like, I don't know, Sevensfield, wouldn't work. I wouldn't even do Smith, because while that's the name that most people automatically think of when they think of common name, it seems so stereotypical. Like, Johnson is really a common name. Smith is only common because we decided it is. I mean, if you think about it, how many people are named Smith? And how many people are Johnson? So I think you get my point, and I get what you mean by it just worked out that way. I've had plenty of characters who I think of a first name and the last name just comes to me. So again, it depends on the name, but overall I'd say just find a knew name, unless it's really that important to you.