First premise: suffering and death from lack of food, shelter, and medical care are bad. Second premise: if it is in your power to prevent something bad from happening, without sacrificing anything nearly as important, it is wrong not to do so. Third premise: by donating to effective charities, you can prevent suffering and death from lack of food, shelter, and medical care, without sacrificing anything nearly as important. Conclusion: therefore, if you do not donate to effective charities, you are doing something wrong.
