The philosopher that wrote How Are We to Live? is known for what 1975 book that argues in favor of vegetarianism?
How Are We to Live?: : Ethics in an Age of Self-Interest is a book on applied ethics by bioethical philosopher Peter Singer. Peter Singer:  He is known in particular for his book "Animal Liberation" (1975), in which he argues in favor of vegetarianism, and his essay "Famine, Affluence, and Morality," in which he argues in favor of donating to help the global poor.
"Animal Liberation"