When I was a kid I got excited about donating money to one of those “Sponsor a third-world child and they’ll write to you” charities. My dad said no, it wouldn’t be right to start if you couldn’t commit to keeping it up for years, and that I’d do better to make a one-time general donation. (I think he was right.)
When you pick out a pet at the shelter/wherever, ideally you are making a commitment till death do us part. What about when you take in a starving stray cat on a cold winter’s night? Can you take it to the shelter in the morning, knowing it will probably be soon put to sleep? (I think yes. You were just preventing it from suffering overnight.) How about keeping it for a few weeks and then taking it in to the shelter? What about if a year goes by – is it now wrong to send it to its death? The longer you live with the cat, the more heartless you’d have to be to off it, right?
You are a rich philanthropist who has built schools in poor countries. Hundreds of kids benefit from the education and dozens of teachers are employed. Now your spouse is diagnosed with stomach cancer and you pull all your funding to put into cancer research. (Seems like you should make some effort to preserve the schools you’ve invested so much in, but is it an ethical requirement?)
I’m juggling some issues in real life that hinge on this question, so I’d appreciate any input.