Crowds at Squires, Library of Congress
Historically, the ethics of peoples has been based on religion. Not surprisingly, morals differ from person to person and place to place because different cultures have different religions.
If there is to be a philosophical basis for how we ought to lead our lives and seek the good life, then this basis probably cannot be founded on religious tenets of God's existence. As we have seen, both á priori and á posteriori proofs for God's existence are not philosophically well developed enough to be reliable for further inferences.
Thus, our task in this part of our study is to see to what extent we can base ethical principles on reason alone. Toward this end, it is important to mention that if scientific determinism were true and psychology is a science with the potential of accurate prediction, it's quite possible the whole enterprise of ethics would be moot, since with no free will, we cannot recommend or freely decide upon alternative courses of decision or action.