The opening of John Stuart Mill's Utilitarianism has often been scoffed at for containing one of the great philosophical boners:

From the dawn of philosophy, the question concerning the summum bonum, or, what is the same thing, concerning the foundation of morality, has been accounted the main problem in speculative thought, has occupied the most gifted intellects, and divided them into sects and schools, carrying on a vigorous warfare against one another.

Hey, I've scoffed at it. The summum bonum is definitely not the same thing as the foundation of morality.

But I realized, recently, that Mill's error is a very common error. He identified two distinct things. And yet, many philosophers are pointing in the direction of the summum bonum when they talk about the foundation of ethics.

Here's the trouble: there is no one foundation for ethics. That is, the article is misplaced. The foundation of ethics? No one such thing.

Why?

The practical foundation of ethics is its function in human society, and the reasons for the use of ethical language and concepts by human beings. Morality is a toolset. Ethical norms, ideals, virtues, etc., are tools for the influencing of human conduct.

But when philosophers talk about a foundation for ethics, they're not always talking about where it comes from, and why its constituent parts have these or those characteristics (though it would be better if they would look at this more often).

No, what they are looking for is a foundation for a particular ethical system. Why this ethical system, and not another? The reason is the foundation for morality. It's why the true morality is, well, true.

Substitute the word fit for true, if you had trouble with the introduction of the word into the discussion. Think of a tool that holds true, that is, is ideally suited to its task.

The task of a universal morality is to prescribe rules that would allow us to live better lives.

How one toolset, with non-vague prescriptions, could be utterly distinct and completely persuasive is one of the troubles of moral philosophy.

But do you see my point? The foundation of ethics, as I describe it, as a social control toolset, is not what people are looking for. This designation and theory (a metaethical theory, not too far from emotivism and prescriptivism) merely describss and helps explain what people are doing when they do ethics.

What they want, on the other hand, is the ideal ethical system.

Determining that is a bit harder.

Why?

Define the perfect saw. Describe the perfect fastener system.

These are tools. But perfection and universality of use? No way. It depends, says the carpenter.

This might be the legitimate answer of moralists to the absolutist demand of the theologian or Kantian moral philosopher.

Or: it could be that the toolkit, evolved over time to meet differing needs, is broad enough and varied enough to handle most circumstances, and the trouble with some moralists is they misidentify which tool they need at which occasion, taking the moral notions of the family and applying them to politics, or vice versa.

And there may be a key in that only some moral notions are universalizable; the rest are up to personal taste, and that's OK.

Another key might be: there is no summum bonum. No greatest good. There are only many goods, and what we must be most on the watch out for are to avoid a number of obvious and dangerous bads, or evils.