Good question Seniya, I get the same thing too!
The most important thing is that it is not about one or the other. It is that taking both is better than taking just one.
Comparative studies give us a unique angle into the suttas, one that reveals things that might otherwise have been hidden. As other commenters have noted, you can’t know the value of research until you’ve done the work. This whole field is still very much in its infancy, and we don’t know what we don’t know. If there is some chance that something might be learned from the Agamas, isn’t it worthwhile?
Let me just state the elephant in the room. Theravadins take their own Pali scriptures as the be-all and end-all of Buddhism, and for the most part are too attached to their own sectarian identity to consider anything else. Which means—and I know this may come as a shock—that Theravadins are human! That’s not a bad thing. It’s better to be attached to something beautiful and profound like the Suttas than to some hateful rubbish. Still, being human, there is a possibility for growth, too.
Let’s address each of the specific points in turn.
True. And this is relevant if your purpose is to understand the entire sutta doctrine of a specific school. However, in reality no-one apart from a few specialists ever does this. Practically speaking we almost always want to know what the meaning of a specific passage is, and the existence or otherwise of other texts of that school is irrelevant.
It’s worth noting in passing, incidentally, that we have a mostly-complete set of Tipitaka texts from the Sarvastivadins: DA (Incomplete and largely unpublished Sanskrit manuscript), MA, SA, part of EA (?), several Dhammapada, Jataka, and similar collections; Vinaya; and all seven of their Abhidharma texts.
The Pali texts will always remain the foundation of our understanding of early Buddhism. I pointed this out in my essay on the Nikayas. But if we can learn from other sources, why wouldn’t we take it?
This is kind of meaningless. The dates tell us little by themselves, and all the evidence suggests that the traditions were pretty good at preserving things.
Which we only know because people did not accept the sectarian notion of scripture, but actually did the work to find out what is going on.
What we should take away from this situation is this. Almost all of the Agamas contain exactly the same doctrines as the Pali canon. And the few occasions where later ideas do appear—which are almost all limited to the EA—are easily identified and well-known to scholars. This shows us two things:
- The schools were reluctant to add new doctrines to the suttas. Like the Theravada, they put their new teachings in separate books.
- Where they did insert things, they did it clumsily, so it is easy to identify.
Sure. But this is well-known to scholars, and is what they work with every day. One point that this overlooks is that understanding of words is the lesser part of textual analysis. Meaning in texts arises at a higher level; and at those higher levels, there is very often no ambiguity at all.
Consider, for example, a stock phrase like the jhana formula. This is found hundreds of times in Pali, so often that it is frequently abbreviated almost entirely. Translation of certain terms in the formula are tricky (kāma, vitakka, etc.) and scholars have different takes on that. In the Chinese texts, there are various renderings, just as there are in modern translations. And if what you want to do is to specifically figure out the meaning of these terms, obviously the Pali is your primary focus of research.
But here’s the thing. There is no doubt that it is the same formula. When it occurs in a Chinese translation, we know just as certainly that this is the jhana formula as we do in Pali. And it frequently turns out that this higher level view is very interesting. For example, the same sutta might contain the jhana formula in a Pali version, but omit it in a Chinese version.