I don't think nationalism is alone holding the field; it's in contention with a lot of different things.

There are a lot of weapons that we've developed which we've pulled back from - biological weapons, chemical weapons, etc. This may be the case with armed autonomous robotics, where we ultimately pull back from them.

Grain that is used to feed animals that end up on our tables as turkeys and hams could have gone to feed starving people.

Without in any way minimising the economic and psychological blow that people experience when they lose their jobs, the unemployed in affluent countries still have a safety net, in the form of social security payments, and usually free healthcare and free education for their children. They also have sanitation and safe drinking water.

I don't think nationalism is alone holding the field; it's in contention with a lot of different things.

The idea that we can actually have an impact on places more or less instantly, too, by responding in some way or not responding, I think, also makes it true.

The statement "I am in pain" may be one piece of evidence for the conclusion that the speaker is in pain, but it is not the only possible evidence, and since people sometimes tell lies, not even the best possible evidence. Even if there were stronger grounds for refusing to attribute pain to those who do not have language, the consequences of this refusal might lead us to reject the conclusion. Human infants and young children are unable to use language. Are we to deny that a year-old child can suffer?