There is a lie going around that the dialect/language question is controversial in Linguistics. It really isn’t. Most linguists have a pretty good idea of where to draw the line. If you don’t believe me, study the internals of the Summer Institute of Linguistics change request forms for languages. The field is a lot more uniform on this question than the cranks think.
Hardly anyone thinks Valencian is a separate language. There were 5-10 experts writing in on Valencian and they were all in agreement.
Romagnolo and Emilian were split with zero controversy. All it took was a few authoritative statements by the experts in these varieties to settle the question.
In other words, the language dialect question is what is known as a fake controversy.
Really the only controversy about this question comes from nationalists and language activists.
Sadly, many linguists are nationalists, and their work has been poisoned by their ideology for a long time now. Some of the worst ones of all are in Europe.
Linguistics in the Balkans and Poland has been badly damaged by nationalist linguists for a long time, with no sign of things getting better.
Similar nonsense is going on in of all places ultra-PC Denmark and Sweden. Bornholmian and Southeast Jutnish should have been split from Danish long ago. In fact, Jutnish was split, but Danish nationalist linguists pathetically had it removed.
The many langues d’oil have never been listed and probably never will be. No doubt this is due to the state of Linguistics in ultra-nationalistic France. There are easily 10-15+ langues d’oil that could be split off.
Greek linguist nationalists have raised their ugly heads over splits in Macro-Greek.
Bulgarian Linguistics is all nationalist and has been lost in retardation forever now. No, Macedonian is not a Bulgarian dialect.
There have been some ugly and ridiculous fights in the Baltics especially with Estonian and Latvian, neither of which is a single language. I doubt that Estonian and Latvian linguists are comporting themselves well here given the fanatical nationalism that overwhelms both lands.
There are easily 350-400 language inside of Sinitic or Chinese according to the estimate of the ultimate Sinologist Jerry Norman. The real figure is clearly closer to 1,000-2,000 separate languages. Chinese nationalism is mandatory for anyone doing Sinitic linguistics. No one wants to bring down the wrath of the Chinese government by pulling the curtain on their big lie that Chinese is one language. I am amazed that SIL even split Chinese into 14 languages without getting deluged with death threats.
Arabic is clearly more than one language, and SIL now has it split into 35 languages. This is one odd case where they may have erred by splitting too much. That’s probably too many, but no one can even do any work in this area, since Arabists and especially Arabic speakers keep insisting, often violently, that Arabic is a single language. Never mind that they routinely can’t understand each other. We have Syrians and Yemenis at my local store, and no, the Syrian Arabic speakers cannot understand hard Yemeni Arabic, sorry. Some of the Yemeni Arabic speakers have even whispered conspiratorially in my ear when the others were not around that speakers of different Yemeni Arabic varieties often cannot even understand each other, and that’s not even split by SIL. I have a feeling that the Arabic situation is more like Chinese than not.
A Swedish nationalist wiped out several well documented separate languages inside of Macro-Swedish simply by making a few dishonest change request forms. SIL pathetically fell for it.
Occitan language activists wiped out the very well-supported split of Occitan into six separate languages based on ideology. They are trying to resurrect Occitan, and they think this will only work if there is one Occitan language with many dialects under it. Splitting it up into six or more languages dooms the tongue. So this was a political argument masquerading as a linguistic one. SIL fell for it again. Pathetic.
No one has talked much about these matters in the field, but a man named Harold Hammerstrom has written some excellent notes about them. He also takes the language/dialect question very seriously and has proposed more scientific ways of doing the splitting.
SIL was recently granted the ability to give out new ISO codes for languages, and since then, SIL has become quite conservative, lumping varieties everywhere in sight. This is because lumping is always the easy way out, as conservatives love lumping in everything from Classification to Historical Linguistics, and the field has been taken over by radical conservatives for some time now. Splitters are kooks, clowns, and laughing stocks. One gets the impression that SIL is terrified to split off new tongues for fear of bad PR.
As noted above, the language/dialect question is not as controversial in the field as Net linguist cranks would have you believe. SIL simply decides whatever they decide, and all the linguists just shrug their shoulders and go back to Optimality Theory, threatening to kill each other over Indo-European reconstructions, scribbling barely readable SJW sociolinguistic blather, or whatever it is they are crunching their brains about.
SIL grants an ISO code or refuses to grant one, and that’s that. No ISO code, no language. The main problem is that they refuse to split many valid languages mostly out of PC fear of causing a furor. Most of the opposition to splitting off new languages comes from linguistic hacks and cranks who exist for the most part on the Internet.
Most real linguists don’t seem to care very much. I know this because I talk to real linguists all the time. When it comes to the dialect/language split, most of them find it mildly intriguing, but hardly anyone is set off. You tell them that some dialect has now been split off as a separate language or two languages have now been merged into one, and they just perk up their ears and say, “Oh, that’s interesting.” Sometimes they shrug their shoulders and say, “They (SIL) are saying this is a separate language now,” as if they really don’t care one way or another.
Linguists definitely get hot under the collar about some things, but not about the dialect/language question, which is regarded more as a quizzical oddity. Most linguists furthermore care nothing at all about the mutual intelligibility debate, which at any rate was resolved long ago by SIL way back in the 1950’s. See the influential book by Cassad written way back then for the final word on the science of mutual intelligibility. Some enterprising linguists are finally starting to take mutual intelligibility seriously, but even they are being much too wishy-washy and unsciency about it. A lot of very silly statements are made like “there is no good, hard scientific way to measure mutual intelligibility, so all figures are guesswork.”
There’s no need for these theoretical shields or hyper-hedging because no one cares. No one in the field other than a few nutcases and kooks on the Internet even gives two damns about this question in the first place. The mutual intelligibility question is actually much less controversial in the field that the linguist kook loudmouths on the Net would have you believe.
We have more important things to fight about, like Everett’s resurrecting of the hated Sapir-Whorf Hypothesis; Chomsky’s Universal Grammar (defended pathetically by the Old Guard and under attack by the Everett crowd who everyone hates); not to mention Altaic; and Joseph Greenberg’s poor, regularly pummeled ghost, along with mass comparison in general.
The field is full of many a silly and pretty lie. One for instance is that Linguistics rejected the Sapir-Whorf Hypothesis long ago, and now it is regarded as a laughing stock. Actually that’s not true. Really a bunch of bullies got together and announced very arrogantly that Sapir-Whorf was crap, and then it become written in stone the way a lot of nonsense our field believes does.
If you go back over the papers that “proved” this matter, it turns out that they never proved one thing. They just said that they proved Sapir-Whorf was nonsense, and everyone fell for it or just got in line like they were supposed to.
Not to mention that Linguistics is like an 8th Grade playground.
Let’s put it this way. If you advocate for Sapir-Whorf in academia, I pray for your soul. You also damn well better have tenure.
I don’t know how anyone advocates for Altaic these days. I would never advocate for Altaic or any remotely controversial historical linguistics hypothesis without tenure.
The field is out for blood, and they burn heretics at the stake all the time. We’ve probably incinerated more wrong thinkers than the Inquisition by now.