Thanks @bridif1 for bringing this up, and resurrecting (rebirthing?) it, and to Bhante @Sujato for his contributions:
Perhaps we could also ask “What use is it? What can be done with it?” My, possibly simplistic, view of physical science is that we have observations, and we have models that can be used to make predictions. We could ask “is a photon real?”, but I tend to think that the idea of “reality” is secondary. Primary is that with the model provided by quantum mechanics we can make accurate predictions, and use that predictive power to engineer things (such as the technology we’re relying on to discuss here…).
Now, it’s not clear to me that Dhamma should be considered to be the same type of knowledge system as Science (I’m suspicious of the idea of trying to reduce all knowledge systems to a single type - we discussed this recently regarding psychology: The Social and Psychological fields - Arts or Sciences?, and I think the same arguments apply to Dhamma). However, if we consider the first-person observations from meditation (and life!) to be our empirical data, and the information in the suttas as our model, then we might ask how the model enables us to eliminate dukkha:
I’ve been recently revisiting Patrick Kearney’s talks on what he calls “life after life”. [Here’s one version: Dharma Seed - Anatta & the problem of life-after-life]
His thesis is that the Buddha was not interested in rebirth as a theory of post-mortem survival. If we take it that way, we’re making Sati’s mistake:
“Absolutely, reverends. As I understand the Buddha’s teachings, it is this very same consciousness that roams and transmigrates, not another.”
And we would likely suffer the same criticism:
“Silly man, who on earth have you ever known me to teach in that way? …
MN38 SuttaCentral
The teaching is about letting go of (among other things) views of self.
Past-life memories are presented in detail in many suttas as a prelude to awakening, e.g. MN4 SuttaCentral
I remembered: ‘There, I was named this, my clan was that, I looked like this, and that was my food. This was how I felt pleasure and pain, and that was how my life ended. When I passed away from that place I was reborn somewhere else. There, too, I was named this, my clan was that, I looked like this, and that was my food. This was how I felt pleasure and pain, and that was how my life ended. When I passed away from that place I was reborn here.’ And so I recollected my many kinds of past lives, with features and details.
So, is the “reality” or not of these memories the point? Or did clearly seeing the identities that he had taken on over countless lives help to understand how fruitless it was to obsess about identity?
After his awakening the Buddha taught, e.g. SN12.20 SuttaCentral
When a noble disciple has clearly seen with right wisdom this dependent origination and these dependently originated phenomena as they are, it’s impossible for them to turn back to the past, thinking:
‘Did I exist in the past? Did I not exist in the past? What was I in the past? How was I in the past? After being what, what did I become in the past?’ …
After awakening, the Buddha is not tied to concepts of beings. Phenomena arise according to causes and conditions. Those phenomena can, of course, be interpreted as the arising of being (a common simile is a river giving rise to whirlpools), but the understanding is not defined by that interpretation (it’s useful to know about the whirlpools if you are kayaking, but the whirlpool is not something separate from the river).
Of course, since I don’t have the Buddhas awakening, I’m still very much tied to concept of self! So I doubt that the above is particularly accurate. However, it does give me a way of approaching Bhante’s question: “What does it mean?”