The Law of Diminishing Marginal Utility

The number of animals who humans inflict suffering on is in the tens, while actually in the hundreds of billions. We could easily reduce this immense amount of suffering by shifting towards plant base diets. Second issue that i've been most concerned about is global poverty. You can do much more good by helping people in low income countries than you can by helping your fellow citizens. It's the law of diminishing marginal utility.