In your example of people not caring about their health: the environmental impact of diet is in a different ethical class for me. If you choose to ignore your own health that's your deal, but if you make choices that negatively impact the lives of millions I think the ethics are different.

The impact of any individual unit of meat consumption by an individual is incredibly marginal. The standard society generally uses to determine whether an individual has harmed another is way higher than that. The satisfaction an individual gets from eating meat might well be greater than the dissatisfaction that instance causes others, and indeed since there's no objective standard it's impossible to measure exactly.

That goes on and on. You may draw a line somewhere and declare "no, from here on it's nonsense", but there's no objectivity, there's no reason why the line should be exactly there, and not, say, on the other side of eating meat.

Empathy for who/what exactly? Eating a steak is not going to cause anybody any measurable pain. Empathy means feeling what somebody else is feeling.

Guests of who, exactly?

Looking at "who was there before and will be after my visit", then human civilization outlives each and every one of us.

And how do we weigh the satisfaction of potential future people against people currently existing? It's not easy; if we assign some value to future people, then that implies we should try to have more children, to maximise the sum total of future people's satisfaction.

>Looking at "who was there before and will be after my visit", then human civilization outlives each and every one of us.

Metaphysically speaking, it's quite possible that every moment of human experience is going to happen anyway, regardless of what we do: https://en.wikipedia.org/wiki/Boltzmann_brain.

Not quite. While it would be true (The Repugnant Conclusion) if every future person had positive quality of life, there can be a point where adding new people pushes everyone's quality of life into negative.

> Metaphysically speaking, it's quite possible that every moment of human experience is going to happen anyway, regardless of what we do: https://en.wikipedia.org/wiki/Boltzmann_brain.

My point was more that the purpose of life could be seen as sustaining the continuity of this civilization. Presumably, Boltzmann brains would not correspond to any civilization more often than any other, so they don't take anything away from the value of a life and the duty to preserve resources.