I agree they are pretty different languages, and you give some solid points as to why: CLOS, dynamic scoping, multi-methods, etc. My point was your link mentioned exactly none of those examples, in fact gave no examples at all, and so wasn't very convincing.

The second point that the argument that Common Lisp is the "true Lisp" because that's why it was made is a faulty syllogism. Just because that was their goal of creating Common Lisp doesn't necessarily mean that is the case.

And Common Lisp isn't the only language with a standard: Scheme had an IEEE standard less than a year after ANSI Common Lisp, and has several RnRS updates since then.

Long story short, I don't think any language should be considered the "true Lisp". Maybe the original Lisp, but even then only as a technicality. And trying to declare a language as the "true Lisp" comes off as a little insulting to related languages and a little bit arrogant. It implies, to a certain degree, that you look down on other languages as lesser, inferior, failed attempts to reach the true zen of Lisp. I'm sure you didn't mean it that way, but as a fan of Scheme (and Common Lisp too!) it reads that way.

Maybe there's no platonic ideal Lisp, and that's the problem, since the thing that makes programmers feel good is some vague sense that there is such an ideal. A sort of god. ;) On the level of communication and definitions though, it seems totally reasonable to me that if your goal as a community of all sorts of versions/dialects of Lisp is to unify into one standard, then you get to call your new unification the Lisp.

I see your point about arrogance, though I think the insulting tone could be turned around easily -- you have these Lisp-like languages that don't even have Lisp in their name nor a lot of Lisp's crucial features trying to appropriate/claim an inheritance on all the hard work and glory and name recognition that went into Common Lisp and its predecessors. Let them have their name. I'm a pretty big fan of Clojure (and do like what Racket is doing when I read up about it) but imagine trying to sell Clojure to an old Lisp hand with "it's like Lisp" and watching them type (inc "a") vs (1+ "a"). https://pastebin.com/kBfNvxei vs https://pastebin.com/hPB2cy1X and there's no contest. (You might win them over with further persistence but they'll probably be wondering where all their favorite parts about Lisp are in this so-called Lisp-like.)

>Is it that absurd? Where is Scheme's CLOS, condition system, built-in debugging framework, and batteries-included standard library? Type declarations? Dynamic scoping? Multi-methods?

Does Lisp from 1960 have these things? Then I guess it isn't really Lisp?

How I see it, Lisp 1.5 was Lisp, but as time went on and many 'versions' of Lisp for different systems with different capabilities came into being, there was no longer really a singular Lisp. Then there was a great unification that spit out Common Lisp, and that became Lisp. So if Lisp 1.5 was released today as something new, it wouldn't be Lisp, but merely another Lisp-like. It's too different. No one today thinks that if you drop "Lisp" in a conversation you really mean Lisp 1.5. (Maybe if you write it as LISP...) It's either going to mean Common Lisp, or maybe a reference to the vague Lisp Family. I don't think Lisp will ever be synonymous with "Scheme".

Maybe you'd appreciate some Lisp history, to also answer your question about "what other dialect[s]"?

http://www.paulgraham.com/thist.html

http://lispm.de/30ycltl

I do know some of the history. I was just asking those questions as a challenge. Regarding the question of the other dialect, the parent used the term as a way of distancing Scheme from what I assume is the one true Lisp: Common Lisp. But the point the passage they had an issue with noted two dialects. The other, of course, being that one true Lisp.

The way I see it, the things that make Lisp "Lisp" are not exclusive to either one. One might say that the intersecting characteristics aren't interesting, but these characteristics are what Lisp is truly about.

SML and Caml are both ML. Haskell 98 and Glasgow Haskell are both Haskell. Dyalog APL and APL2 are both APL. And so on.

He was just giving those as examples of ways in which Scheme and Common Lisp differ. Which is a fair point. Of course it does raise the question: are those features essential attributes of the Platonic ideal that is True Lisp, or simply nice addons Common Lisp provides?

Yeah, that's what I was getting at.

No, but the Common Lisp of 1984 has much of the Lisp of 1960. It's backwards compatible in many ways.