ethics without rebirth?

Some, such as Bhikkhu Punnadhammo, argue that rebirth is the crux of Buddhist ethics, and that discarding the doctrine of rebirth amounts to discarding the very ethical basis of Buddhism itself. But is that really the case? Personally, I don't think so.

For starters, I'd say that rebirth is more like an ethical carrot and stick than anything (good rebirth = carrot, bad rebirth = stick). The real underlying principles behind Buddhist ethics, however, are kamma — the idea that certain actions produce pleasant, painful or neutral feelings/results — and ahimsa or harmlessness.

Essentially, Buddhist ethics revolve around seeing our desires for happiness and freedom from pain in all living creatures. If we don't respect that in them, how can we ever expect the same? This is especially true regarding human beings.

Here I agree with the Buddha that, besides some rare and special cases, there's no one that's as dear to us as ourselves, that all beings essentially want to be happy in their own way (according to their specific capacities), and that it's a fairly decent and logical reason to desire their happiness as well as our own (SN 3.8).

The reason is simple. If our happiness comes at the expense of their happiness, they'll do everything in their power to upset that happiness. Conversely, if they were to infringe upon ours, wouldn't it follow that we'd do everything in our power to upset theirs? It seems like a vicious circle to me, and one of the ways to break this circle is an ethical framework that takes the happiness of others into consideration.

This, in turn, can eventually lead to the development of things like compassion and generosity, among others (such as the wings to awakening), which takes what was once a selfish or self-centred desire for happiness and transforms it into a selfless desire/achievement.

While rebirth easily fits into this framework, and has traditionally been a source of motivation for ethical behaviour in Buddhism, I don't see it as the 'basis' since you can just as easily remove it from the equation and the framework itself still stands. At least that's how I see it, anyway.