David N. Snyder wrote:What would Buddha do?
I don't think this should be a problem for the Buddha of the pali tipitaka. He can see the kamma of others, so he would act accordingly based on the ripening of kamma involved.
It's only a dilemma for the rest of us.
A virtue ethicist would not flip the switch.
A utilitarian or a lay Buddhist would just flip the switch. Having right intention, there is no killing intent present and therefore no unwholesome kamma accumulated. Unless the guy on the other track is an arahant, in which case the lay Buddhist is kammically screwed for a minimum of 1.62×10^12 years.

