Seeing the thread on scientific proof of rebirth, I thought it might be interesting to talk about philosophically defending it.
The traditional Theravadin defense of the rebirth seems to be mainly a religious argument (I have no problem with that) based on the authority of the Buddha. This is fine for those who accept his authority, but I think we can do a bit better.
Historically, the only Buddhist I can think that provided a solid argument for rebirth is Dharmakirti - and this argument is the one that modern Tibetans rely on without having changed much.
His argument was mainly that mind is irreducible to matter, and hence a mental phenomenon has to have been caused by a past mental phenomenon at the moment of conception (which means it must have come from a past life). Hayes gives a good overview here: https://www.unm.edu/~rhayes/rebirth.pdf
I thought perhaps we could update his argument today in the following way:
Physicalism and specifically Emergentism is wrong. Mental phenomena are non-reducible to physical phenomena. (In this step I would basically refer people to the modern philosophical literature on philosophy of mind, needless to say, I support the critics of physicalism)
Mental phenomena have as one of their necessary causes other mental phenomena (as well as other physical phenomena).
There must have been a mental phenomena which stretches back before my birth which conditioned my first mental activity in this life.
Since this causal stream of mental phenomena have causally interacted with this body at this time, it is likely that it will causally interact with another body in the future and has causally interacted with other bodies in the past.
But wait there’s more! Here’s my second argument free of charge, this one is not based on Dharmakirti:
Physicalism and specifically Emergentism is wrong.
Mental phenomena interact in some way with physical phenomena causally, and hence must follow similar or analogous laws.
Information and energy cannot be created or destroyed (this is confirmed by modern physics).
Mental phenomena or the information contained therein survive death in some way.
There is the possibility for this information/phenomena to become embodied again in the future (it was embodied before, it can be so again).
Thoughts? I am not a professional philosopher by any means so this is probably the best I can do at taking a crack at this thing. It probably is not perfectly convincing but perhaps someone else can make them better?
Edit: Also, I totally forgot to mention that there is an argument in the Western tradition which comes from Plato and possibly Socrates and goes something like this;
Persons have certain innate knowledge (like the fact that two proportional triangles have equal interior angles)
This would only be possible if we learned it before our birth.
But I am not totally sure if this is a very strong argument in any case