The existence of indo-european languages is itself ironclad evidence of the existence of a proto-indo-european language. The alternative would be that each of the populations speaking an indo-european language just made up identical vocabulary independently.

Details of PIE are subject to revision based on new evidence. Its existence is not in question.

I think what you are saying is that the existence of indo-european languages could only reasonably be explained by them having originated from a common ancestral language. I agree with you.

The open question is whether this common ancestral language is the imagined / reconstructed extinct language called Proto-Indo-European that does not currently have any supporting physical evidence (cave paintings, stone carvings, Papyrus manuscripts, tablets, and whatnot) proving its existence, or is it one of the many surviving languages still spoken today?

I don't think we know the answer to that question.

PIE is, exactly, the name of that ancestral language. We are able to deduce many details of that language from a large amount of distributed evidence about extant languages and extinct written languages. A great many details have been elucidated from this evidence, more all the time. Sometimes new evidence leads to changes to the deduced model.

It is hard to understand what you think is the difference between the ancestral language and PIE. PIE was almost certainly not a written language, so carvings or manuscripts can exist only in fantasies. We have enormous evidence of the existence of non-written languages.

It should be obvious that a non-written language from 8000 years ago would not be spoken today, just as much newer languages Latin and Sanskrit are long dead, as was Hebrew until artificially revived. Spoken Hebrew is evolving fast.

Assuming PIE existed, you would be right. I am not saying it didn't.

While of course no PIE writings have been ever found, it's interesting that we have also not found references to PIE anywhere in writings in any other languages, from the times of the Sumerian Script all the way until William Jones showed up (or until slightly before his time). Please correct me if I am wrong.

William Jones was a sharp cookie to theorize PIE, no doubt. But for us to believe in the existence of PIE, we have to believe that there was no other cookie sharp enough elsewhere in the world, between 3400 BC (Sumerian Script) and 1786 AD (William Jones) who could have looked at Latin, Greek, Hebrew, Arabic, Sanskrit, and Persian, like Jones did, and derived a theory similar to PIE, and written about it.

One possible explanation could be that people who came before us considered this idea, and discarded it due to lack of sufficient merit, and we are simply reinventing that wheel.

On another note, all the old assertions regarding the death and follow on artificial revival of Sanskrit have been invalidated. Sanskrit, as a language, has stayed very much alive since ancient times. References:

- Hatcher, Brian A. (2016). "Sanskrit and the morning after". The Indian Economic & Social History Review. 44 (3): 333–361. doi:10.1177/001946460704400303. ISSN 0019-4646. S2CID 144219653

- Hanneder, J. (2009), "Modernes Sanskrit: eine vergessene Literatur", in Straube, Martin; Steiner, Roland; Soni, Jayandra; Hahn, Michael; Demoto, Mitsuyo (eds.), Pāsādikadānaṃ: Festschrift für Bhikkhu Pāsādika, Indica et Tibetica Verlag, pp. 205–228

- Seth, Sanjay (2007). Subject Lessons: The Western education of colonial India. Durham, NC: Duke University Press. pp. 172–176. ISBN 978-0-8223-4105-5.

Since I got downvoted and accused of "pointless contrarianism" elsewhere in this thread, I would like to say that I am not trying to offend anyone, nor waste anyone's time with my questions/thoughts/explanations. I am bringing up an issue that I think deserves discussion. I don't see what the problem is. If you don't like what I have to say, scroll past my comment. If you like what I have to say, I am happy to engage.

Maybe PIE speakers invented all of chemistry, general relativity, and quantum mechanics 8000 years ago, but owing to lack of any written language or higher-math educational institutions, their descendants have since forgotten it all. But it is not the way to bet.

You already admitted that an ancestor to the PIE-family languages existed. Are you objecting to linguists calling that ancestral language PIE? Maybe you have some other name to propose, and would like to persuade the entire population of modern linguists to switch to using your proposed name that you have not revealed to us yet?

You were downvoted for reasons you could learn from. Maybe read the posting guidelines?

What is your proposed theory? It is understandable to be sceptical considering the scandal that was proto-altaic, however there is evidence in form of successful reconstructions of PIE languages.

This brings up the topic of standard of evidence that's considered acceptable in various fields. Successful reconstruction of PIE languages is similar to mathematical derivations in theoretical physics. In physics, successful derivation of mathematical results would not be considered "evidence". Evidence is mostly limited to observed phenomenon. Linguistics as a field seems to accept reconstructions as evidence. Which is cool. But it is interesting to consider the implications of using the standard of evidence of physics as applied to Linguistics, because it would certainly weaken (not eliminate) the case for PIE. It may create space for inquiry into non-PIE-assumed theoretical work.

This is interesting. If PIE did not actually exist, what language would be the root instead? Because chronologically, there does need to be some root language that explains the patterns.

My question got downvoted. I wonder whose feathers I ruffled.

People who do not like pointless contrarianism like your comment.