The atheist Euthyphro Dilemma

 The Euthyphro Dilemma is usually formulated against Christians as:

1) Does God choose what is good because it is good,

2) or does God chose what is good?

For the Christian, neither choice is acceptable.

To affirm that God choose what is good because it is good is to establish an autonomous moral principle that has authority over Him

To affirm what is good is whatever God has said it is to render morality arbitrary

The solution for the Christian is a 3rd option: God is Good itself. Since God is simultaneously the source and the measure of all goodness, the dilemma disappears.

But the atheist has an Euthyphro Dilemma of their own concerning the source of their morality:

A common atheist view of morality is that human instinct/society has decided that human well-being [Or harm mitigation] as the root of morality. Both atheistic views of morality often require people to act against their interests.

However:

The Marquis de Sade an atheist philosopher, concluded that Nature teaches us the principle that the strong ought to rule over and therefore exploit the weak.

Friedrich Nietzsche atheist philosopher, said a healthy society does not exist for its own sake, but exists for the sake of a higher type of person.

Both philosophers chose instincts such as the desire to dominate and cruelty, which are the antithesis of the "human well-being/harm mitigation" morality. The question therefore arises: why should we choose a "well-being or harm mitigation" morality over those of the Marquis de Sade and Nietzsche?

To argue that our morality’s source is human instinct/society means that we have no reason to prefer a "well-being or harm mitigation" morality over the Marquis de Sade and Nietzsche’s, since their moralities are derived from the same human understanding as today's atheists who should be aware of the fact that there are humans who do not have the same instinct for compassion as they do. So why prefer one morality over another?

Why should the human instinct/society be the arbiter of what is good? We look to history to see that it has been wrong in the past: Abolitionists held the minority view during most of human history, yet their anti-slavery philosophy is now almost universally accepted, except for the minority who continue to enslave people today.

If, as atheists assert, human instinct/society is the source of their "well-being or no harm mitigation" morality, a Euthyphro-style Dilemma arises.

The atheist Euthyphro-style Dilemma is this:

1) is a "well-being or no harm/harm mitigation morality" good because human instinct/society says so, or

2) is it morally good because it is a good?

If they say it is morally good because human instinct/society says so, then they run into the problem of those who feel/operate according to different instincts - aka Nietzsche and the Marquis de Sade. Why well-being or no harm/harm mitigation morality" over Nietzsche and the Marquis de Sade?

If we say it is morally good because it is good or benevolent, then we admit a morality is external to us.

Whereas theists argue that morality’s external source is God, atheists who wish to adhere to an external morality have the burden of demonstrating this morality’s external source.

I suppose that a 3rd option would be that which best helps humans survive as a species, but why humans? What makes us special? Why not cockroaches or rats or the tardigrade? If it's about well-being or harm mitigation, those 3 probably caused less harm than humans combined...