I take it that the language itself presents a variety of phonemes, but makes no structural demands on a traditional system of ordering— which is why so many (presumably the vast majority) of historical writing systems have arranged their characters more or less haphazardly. In fact a single standardized ordering is not theoretically necessary even for literacy: we could both have learned every letter of the Roman alphabet and become equally literate without having used the same ordering of letters to do so. Certainly no “underlying structure” of English (or of Latin, had we been ancient Romans) would lead us both to arrive at the same ordering independently.

You are right, of course, that in this post I only presented the characters of an extended Roman set, and not the Devanagari equivalents, since most of my audience would not recognize the latter. But this transliteration scheme was not developed as a natural consequence of the structure of Sanskrit, nor would it be likely to have arrived at this arrangement from mere consideration of the language independently of any other script: it was developed specifically to have one-to-one correspondence with Devanagari and related Indic scripts, and inherited its order from them, not from a deeper structure in the languages they are used to write. And now that the ordering is learned in tandem with the script—wherever the ordering originally came from—it is shared with speakers and writers of other languages that presumably have quite different “underlying structures,” including, for instance, Nepal Bhasa, whose “structures” are not even Indo-European, and which would nevertheless appear not to interfere with the ordering, or even to suggest a different one more natural for its own structures.

My main point here was that the ordering of characters in a writing system—though it may certainly be a feature of the interests and preoccupations of the people who formulate it—is most likely not a feature intrinsic to the language itself. In a different history, the languages of India might have been written in arbitrarily ordered scripts, and the languages of the Mediterranean in ones with such orderly phonemic arrangement; I am suggesting that India deserves credit for its totally awesome invention, but that it most likely is not a simple consequence of the structure of the language, which would just as easily have been accommodated by any arbitrary ordering.

I believe it remains contentious (and it might finally be unanswerable) whether the Prakrits evolved from early Sanskrit, or if early Sanskrit was merely one of many related dialects that became a prestige variety.

I have no contention with the (it seems to me quite probable) claim that the phonemic ordering I praise here predates Devanagari. I did make explicit in my original post that this ordering is shared by other, related scripts (no one of which I should consider less awesome than Devanagari, though I don’t know them), and I presume they inherited it from a common source. However, I have no way of evaluating the claim that this ordering predates any script. It seems rather improbable to me, but many claims about ancient India seem rather improbable to me, and some of them are true, so this one might be as well. I’d be interested to see evidence one way or the other. But I would continue to think that it is not properly a feature of the language—since it works just as well for other languages, and other orderings work just as well for this one—even if it is a very ancient and even pre-literate feature of the culture that grew up around the language.

“So the consonants in Devanagari are arranged like so:

k — kh — g — gh — ṅ
c — ch — j — jh — ñ
ṭ — ṭh — ḍ — ḍh — ṇ
t — th — d — dh — n
p — ph — b — bh — m”

This is wrong. The consonants of Sanskrit written in an extended version of the Roman script is as presented. The consonants of the Sanskrit language in the Devanagari script are like so:

क – ख – ग – घ – ङ
च – छ – ज – झ – ञ
ट – ठ – ड – ढ – ण
त – थ – द – ध – न
प – फ – ब – भ – म

But the ordering of the phonemes is the same and the ordering predates any script, Devanagari or otherwise. The Devanagari script itself evolved out of Brahmi script, which was developed for a series of Prakrit languages for the Emporer Ashok. The Prakrit languages, in turn, had evolved out of early Sanskrit, most likely in conversation with Dravidian precursors.

But it is not clear to me how a structure of the Sanskrit language itself is responsible for this, or any other, ordering of sounds.

My understanding—which may very well be mistaken—is that something like this ordering is used for most or all of the family of brahmi scripts, most or all of which are used for writing languages that are not Sanskrit, and many of which are used for languages that are not even Indo-European. Unless these scripts all inherited their ordering from Devanagari or a precursor to Devanagari which itself was formulated specifically to write Sanskrit (which I do not believe to be the case), it would seem that this ordering is not due to any structural demands of Sanskrit. Perhaps it is due to a cultural feature of the people who inherited the Vedas, but I don’t see how their language (or any one of their languages) is by its nature more or less given than any other to be written in such a phonologically ordered script.

Also, though it is an aside, I am given to understand that there is considerable uncertainty about dating Pāṇini, and controversy over whether he is “pre-writing in South Asia.”

Once writing happens the orality of Sanskrit is, in my opinion, a ideologically-driven fiction, as evidenced by the sections of bandha forms of citra in the earliest kavya, as well as, less concretely, the obsessive nature of the protestations to the “fact” of orality.

If you mean that this ordering is a consequence of Sanskrit itself, or of the people who used it, I think there might be a case to make that it’s less fundamentally a fact of the script than a consequence of the culture, and especially with regard to the position of the Vedas. But it’s not demanded by or necessary for the language. And it’s shared by many other languages besides Sanskrit that use the same or related scripts.

All human languages are script-independent. That’s why so many scripts are used across multiple, sometimes even unrelated languages; and why so many languages have been written in multiple scripts. It is an interesting fact that, for a literary language, Sanskrit has seemed unusually unattached to one particular script, and maybe that’s what you’re suggesting. It’s a fact that might reflect the unusual regard for the sounds of the language, over and above the look of it on the page, which regard also resulted in the careful structure of the native scripts.

Does ‘क’ somehow mean unvoiced, unaspirated velar stop when ‘ka’ does not?

Sanskrit is wonderfully script-independent. To me it’s one of its charms.