{ 1 } - we ought to treat others as we want to be treated.
{ 2 } - a desire or action can violate reason only by being based on a factual error or by picking means insufficient to our ends.
{ 3 } - we can't deduce an "ought" from an "is."
{ 4 } - "ought" implies "can."

In other words, moral conclusions can't be deduced from descriptive premises alone. We need a moral premise to deduce a moral conclusion.

So we can't give facts about society (or evolution, or God, or desires, or whatever) -- and then from these alone logically deduce a moral conclusion. We could always consistently accept the facts and yet reject the moral conclusion. It follows that neither science nor religion can establish the basic principles of morality.