The founders used the term "self evident," but Ayn Rand improved on that in the "Objectivist Ethics," writing ...
To challenge the basic premise of any discipline, one must begin at the beginning. In ethics, one must begin by asking: What are values? Why does man need them?
"Value" is that which one acts to gain and/or keep. The concept "value" is not a primary; it presupposes an answer to the question: of value to whom and for what? It presupposes an entity capable of acting to achieve a goal in the face of an alternative. Where no alternative exists, no goals and no values are possible.
Ayn Rand goes on to discuss the importance of life to living organisms, and humans in particular, saying ...
In answer to those philosophers who claim that no relation can be established between ultimate ends or values and the facts of reality, let me stress that the fact that living organisms exist and function necessitates the existence of values and of an ultimate value which for any given living entity is its own life. Thus the validation of value judgments is to be achieved by reference to the facts of reality. The fact that a living entity is, determines what it ought to do.
A brilliant piece of work, twenty two pages long -- chapter one in "The Virtue of Selfishness."
That title, by the way, was chosen specifically for its shock value because today's world considers seflishness evil. Rand writes that ... " The exact meaning and dictionary definition of the word "selfishness" is "concern with one's own interests."
How about that? Ayn Rand's ethics holds that taking care of one's family first is not evil.