At the descriptive level, certainly, you would expect different cultures to develop different sorts of ethics and obviously they have; that doesn't mean that you can't think of overarching ethical principles you would want people to follow in all kinds of places.

Of all the arguments against voluntary euthanasia, the most influential is the slippery slope: once we allow doctors to kill patients, we will not be able to limit the killing to those who want to die.

Animal factories are one more sign of the extent to which our technological capacities have advanced faster than our ethics.

Becoming a vegan is a sure way of completely avoiding participation in the abuse of farmed animals. Vegans are a living demonstration of the fact that we do not need to exploit animals for food.

Suppose I grant that pigs and dogs are self-aware to some degree, and do have thoughts about things in the future. That would provide some reason for thinking it intrinsically wrong to kill them - not absolutely wrong, but perhaps quite a serious wrong. Still, there are other animals - chickens maybe, or fish - who can feel pain but don't have any self-awareness or capacity for thinking about the future. For those animals, you haven't given me any reason why painless killing would be wrong, if other animals take their place and lead an equally good life.

Of course, infanticide needs to be strictly legally controlled and rare - but it should not be ruled out, any more than abortion.

Human decision-making is complex. On our own, our tendency to yield to short-term temptations, and even to addictions, may be too strong for our rational, long-term planning.