In college, I took a course called Problems in Philosophy. Near the end of the semester, I sat in the back of the lecture hall, probably trying to discreetly eat a peanut-butter-and-jelly sandwich and trying to satisfy my participation requirement by speaking exactly once, while the class discussed Peter Singer’s argument that the moral logic we apply to everyday life implies that we are obligated to forgo small luxuries in order to give to the very poor:
“To challenge my students to think about the ethics of what we owe to people in need, I ask them to imagine that their route to the university takes them past a shallow pond. One morning, I say to them, you notice a child has fallen in and appears to be drowning. To wade in and pull the child out would be easy but it will mean that you get your clothes wet and muddy, and by the time you go home and change you will have missed your first class.
I then ask the students: do you have any obligation to rescue the child? Unanimously, the students say they do. The importance of saving a child so far outweighs the cost of getting one’s clothes muddy and missing a class, that they refuse to consider it any kind of excuse for not saving the child. Does it make a difference, I ask, that there are other people walking past the pond who would equally be able to rescue the child but are not doing so? No, the students reply, the fact that others are not doing what they ought to do is no reason why I should not do what I ought to do.
Once we are all clear about our obligations to rescue the drowning child in front of us, I ask: would it make any difference if the child were far away, in another country perhaps, but similarly in danger of death, and equally within your means to save, at no great cost – and absolutely no danger – to yourself? Virtually all agree that distance and nationality make no moral difference to the situation. I then point out that we are all in that situation of the person passing the shallow pond: we can all save lives of people, both children and adults, who would otherwise die, and we can do so at a very small cost to us: the cost of a new CD, a shirt or a night out at a restaurant or concert, can mean the difference between life and death to more than one person somewhere in the world – and overseas aid agencies like Oxfam overcome the problem of acting at a distance.
At this point the students raise various practical difficulties. Can we be sure that our donation will really get to the people who need it? Doesn’t most aid get swallowed up in administrative costs, or waste, or downright corruption? Isn’t the real problem the growing world population, and is there any point in saving lives until the problem has been solved? These questions can all be answered: but I also point out that even if a substantial proportion of our donations were wasted, the cost to us of making the donation is so small, compared to the benefits that it provides when it, or some of it, does get through to those who need our help, that we would still be saving lives at a small cost to ourselves – even if aid organizations were much less efficient than they actually are.
I am always struck by how few students challenge the underlying ethics of the idea that we ought to save the lives of strangers when we can do so at relatively little cost to ourselves.”
I heard this argument, found it airtight, and was terrified. Was it wrong to buy a cup of coffee? Would I have to give up all of life’s small delights in order to help others? I was already spending as little money as possible — I ate mostly rice, peanut butter, and bananas, and refused to buy “luxuries” like salt — and I didn’t want to live that way forever. I decided that Singer’s argument was too extreme, that it had to be wrong even though I couldn’t articulate why.  I tried to push it out of my head for a year, but couldn’t. I slowly accustomed myself to the idea of living on very little. I realized that I didn’t need a big house, foreign vacations, or frequent restaurant meals to be happy. (I also learned that a year’s worth of salt costs about a dollar and that I should buy that sort of thing instead of torturing myself.)
Second semester sophomore year, I saw a corner of a formal-looking letter peeking out from my boyfriend’s desk drawer. I snooped and found out that he had become a member of Giving What We Can: he pledged to donate everything he made over some threshold to charities that work to alleviate global poverty. We talked, and talked, and I started donating to charities recommended by Giving What We Can and Givewell.
A year or so later, I got real about living far less luxuriously than the median American. I calculated the cost of rent, food, taxes, and insurance, and decided that I could comfortably live on about $18,000 per year, or far less if I moved to a less expensive area.  I also joined Giving What We Can, and pledged to donate the greater of 10% of my income or everything I made over $34k, post-tax and inflation-adjusted.
All of my friends have nicer homes than the 450 square foot one-bedroom that my fiancé and I pretend has two bedrooms. I have only ever paid for one trip that wasn’t for the purpose of visiting my or my boyfriend’s family, and it cost about $400. I’ve spent a lot of time figuring out how to cook cheap but healthy food. I don’t feel deprived, because as long as I save money on the big things, I can afford to eat out regularly and buy clothes that don’t have holes in them. In fact, joining Giving What We Can has relieved a lot of anxiety. I gave myself a $100 a month discretionary/fun budget and a $1000 a year travel budget, and as long as I stay inside that range, I don’t feel guilty about spending money on myself instead of donating it.
After college, I found out that there’s a movement behind the conclusions that I thought my boyfriend and I had come to on our own. “Effective Altruists” hold that people should be more altruistic and should try to have the greatest impact possible, which may mean to donating to cost-effective charities, working in an altruistic job, or earning as much money as possible in order to donate it. They are friendly and have Meetups and stuff.
 While it’s possible to save a life for the cost of a night out, it isn’t likely. For example, it costs about $5 for the Against Malaria Foundation, one of the most cost-effective charities, to provide a bed net, explain how to use it, and return months later to ensure that it is being used. Although malaria is very prevalent in some tropical countries, it causes death far less often than you would think; various organizations have estimated a cost per life saved of about $4000 for AMF. (Going off memory, don’t quote me.) However, a thousand bed nets make hundreds of people healthier even if they don’t save a life. Perhaps we should ask if we are morally obligated to move into an apartment that costs $150 less per month if doing so saves a life every two years.
 Two years out of college, these calculations seem pretty accurate. I’ve actually paid off my college loans and have been saving a large fraction of my grad student stipend.