It expresses pretty much all of the core principals of a LISP. If it looks like a LISP, thinks like a LISP, behaves like a LISP; then do you really gain anything by trying to separate from other LISPs?

Or less extremely, why don't we consider Python and Ruby to be the same family, or Java and C#? Those pairs are arguably more similar than the pair of Common Lisp and Scheme.

The dialects of Dutch in Belgium contain completely different words and phrases - but the core is still Dutch.

But for large parts of the speech they are recognisably similar.

So I'd say yes all the lisps you mentioned are dialects of Lisp. You can't run one directly in the other, but they are reconisably similar programming constructs.

Referring to the broad Algol-family isn't uncommon (well, at least, I do it quite a bit.)

> Or less extremely, why don't we consider Python and Ruby to be the same family, or Java and C#? Those pairs are arguably more similar than the pair of Common Lisp and Scheme.

Java and C# are frequently described as being part of a single close language family (much closer than the broad Algol-family; sometimes in an intermediate-breadth family that also includes ), and Ruby and Python are much less similar than Scheme and Common Lisp.

We sometimes do though, don't we? Not that terminology, but I often see the people talking about "curly brace languages" or "C/C++/Java/C#".

Edit: In hindsight at the end of the day I should have been more careful with the "Scheme is not Lisp" (at least I didn't say "Scheme is not a Lisp") comment...I'm only continuing these threads because I read the original submission pretty close to when it was posted and back then I only knew a bit of SICP, tried enough Lisp to duplicate some SICP examples, and was frustrated with the Lisp-2 syntax along with what I perceived as a REPL freakout on any error so I put Lisp aside. It would have been helpful for someone to tell me "Scheme is not Lisp" back then and get me to actually explore all that Common Lisp has to offer.