Having discussed the broader context of Śāntideva’s work, I think it is instructive to turn now to the two passages that Evan Thompson quotes from Śāntideva’s Bodhicaryāvatāra as supposed examples of the way that Śāntideva’s “philosophical arguments fall apart” without rebirth. These respectively say (in the Wallace and Wallace translation he cites), first, “In the past, I too have inflicted such pain on sentient beings; therefore, I, who have caused harm to sentient beings, deserve that in return./Both his weapon and my body are causes of suffering. He has obtained a weapon, and I have obtained a body. With what should I be angry?” (BCA VI.42-43) And second, “since my adversary assists me in my Bodhisattva way of life, I should long for him like a treasure discovered in the house and acquired without effort.” (VI.107)
Note first of all that neither of these passages explicitly make any mention of rebirth. And I think that both would make sense even if rebirth were not involved. On the second (BCA VI.107), I’m not even sure Śāntideva is himself thinking about past lives at all. This discussion of adversaries seems to me an inspiring passage on patient endurance in this life: those who oppose us help us develop the virtue (specifically patient endurance) that leads us to a better life.
Regarding the first (BCA VI.42-3), on previous harm inflicted on sentient beings, I agree that here Śāntideva is probably thinking about past lives, but it is important to point out that even here he does not specify this. More importantly, I think the logic of the passage still works in a this-worldly way. Notice that Śāntideva is not saying I have caused harm to this sentient being, the one who is harming me right now. Rather, he is just saying I have caused harm to sentient beings in the past, and that therefore I deserve it I return. And who among us has not inflicted significant pain on other sentient beings – intentionally or otherwise – in this present life? The pain I receive now may well be disproportionate to the pain I have inflicted, but I don’t think proportion is the point of the passage: in the larger context of the chapter, the point of this passage is to remind us that we are not innocent, as one more way to prevent the anger that he has explicitly said is destructive to ourselves, in this life and another. In neither of these two passages that Thompson himself cites as exemplary, then, is it the case that “the eudaimonistic aspect of karma—that good mental actions bring about good results—has no warrant and motivation” without rebirth.
Thompson wants us instead to see these passages as part of “the mind-expanding Mahāyāna narrative in which all beings strive over countless aeons to be happy and every sentient being has been your mother”. But they aren’t! The idea that every being has been one’s mother does appear in many Tibetan commentaries on Śāntideva – perhaps the majority of them – but it never appears in Śāntideva’s own writings. I don’t recall ever having seen it in any other Indian Buddhist source, either. Indeed it is perhaps the place where I see the most striking contrast between Śāntideva’s own words and the way the Tibetans interpret him; from what I have seen, the overall Tibetan Buddhist worldview is generally more pro-familial than the Indian. Those Tibetan interpretations are one reasonable way to interpret Śāntideva, but they are not Śāntideva’s own words or thoughts, any more than naturalized karma is. Those Tibetans, too, are innovating. They are putting their own spin on Śāntideva’s words just as we modernist Buddhists are. Since our discussion is all about innovations to tradition, I think it is important to be crystal-clear about that.
Moreover, since “cherry-picking” can refer to picking passages in isolation without their context, let’s be clear about the specific context of both of the passages Thompson quotes. They are not in the chapter of the BCA on metaphysical insight or understanding (prajñā); their primary purpose is not understanding the world or its events. If we were to take the point of these passages as to “give you a way to understand and respond to all the bad things that happen to you in this life, even if they seem undeserved”, an appropriate word for what we were doing would indeed be “cherry-picking”. For if we look at them in context, we see that that is not their purpose. (Thompson is welcome to draw inspiration from those passages for the concerns about theodicy that so clearly bother him, but he should not pretend that they were what motivated Śāntideva to compose them.)
Rather, these passages are part and parcel of the chapter on patient endurance (kṣānti), whose primary purpose is to enjoin us to avoid anger – framed, at its opening, by the passage I quoted earlier, about the bad consequences of anger iha paratra ca. The bad mental action of anger leads to bad results, for us as well as for others, in this life and in future ones – it interferes with flourishing – and therefore it is to be avoided. In Śāntideva’s own intention and worldview (a worldview which includes rebirth), the primary purpose of the passages in this chapter is not to give us a way of understanding others’ bad actions, but to show us why anger is not justified. As far as understanding others’ bad actions goes, the quoted point about past harm one has oneself caused others takes up less than a verse. Rather, when Śāntideva talks at length about understanding others’ bad actions, it is in making an argument against free will (VI.22-33), pointing out that others’ actions are deterministically caused and therefore not subject to blame. That longer passage also makes no reference to rebirth or multiple lives. Rebirth is in the background of all of these discussions for Śāntideva, but it is far from the only thing that informs them.
It’s in the later chapter on metaphysical insight (chapter IX), rather than the chapter Thompson quotes from (chapter VI), where Śāntideva is trying to describe the nature of the world and events in it – where understanding is his main purpose. But Śāntideva’s primary metaphysical commitment there, which later tradition often views as the climax of the book, is not to a cosmology of ethicized rebirth. Rather, it is to the emptiness of all things, including karma and rebirth themselves. The upshot of that commitment for our lives is to acknowledge the emptiness of all those things, including action and its fruits, and respond to it with a complete detachment from them, a sense of their unworthiness. I do disagree with Śāntideva on that score as well, for reasons I’ve already noted – and it is that point, not rebirth or its absence, that is really at the heart of my disagreement with him and other traditional Indian Buddhists. Rebirth is less important, to Śāntideva and to me.
Now there are some important ways that removing rebirth from Śāntideva’s worldview poses problems for it. Most important of these is the suicide objection: if the goal is an end to suffering and there is no rebirth, should we not just kill ourselves – or even kill others, if we are Mahāyānists? My own response to that objection, which Śāntideva would disagree with in my formulation of it, is that there are worthy goods other than the ending of suffering. But Śāntideva himself does seem to think that bodhisattvas overflow with happiness in the life that they have, though he has some other passages to the contrary; even on his view, the bodhisattva’s life may well be better than nonexistence, for oneself and for others.
In all, I cannot accept Thompson’s accusation that I am cherry-picking Śāntideva’s worldview. I am aware that Śāntideva believed firmly in rebirth. I am also aware that there is now significant evidence indicating that ethicized rebirth, of the sort that Śāntideva believed in, does not actually happen. I think that my approach of naturalizing his worldview is considerably more faithful to Śāntideva than is an approach that says “well, everything he says depends on rebirth, so if rebirth isn’t real then he’s completely wrong and we shouldn’t view our approach as following his in any way”.