Finally, it’s ten percent because if you believe in something like universalizability as a foundation for morality, a world in which everybody gives ten percent of their income to charity is a world where about seven trillion dollars go to charity a year. Solving global poverty forever is estimated to cost about $100 billion a year for the couple-decade length of the project. That’s about two percent of the money that would suddenly become available. If charity got seven trillion dollars a year, the first year would give us enough to solve global poverty, eliminate all treatable diseases, fund research into the untreatable ones for approximately the next forever, educate anybody who needs educating, feed anybody who needs feeding, fund an unparalleled renaissance in the arts, permamently save every rainforest in the world, and have enough left over to launch five or six different manned missions to Mars. That would be the first year . Goodness only knows what would happen in Year 2.