Traditionally understood as the "first principle" of morality, the dictum "do good and avoid evil" lends some moral content to this principle. The principle of beneficence is a "middle principle" insofar as it is partially dependent for its content on how one defines the concepts of the good and goodness. As a middle principle, beneficence is not a specific moral rule and cannot by itself tell us what concrete actions constitute doing good and avoiding evil.
The Principle of Nonmaleficence, Primum non nocere, commonly translated as "first, do no harm," is often considered to be a corollary to the principle of beneficence. In this respect, it shares the same characteristics of beneficence and is considered as a middle principle. Considered in its own right, nonmaleficence is sometimes interpreted to imply that if one cannot do good without also causing harm, then one should not act at all (in that particular circumstance). The difficulty with this rigorist interpretation, however, is that it makes action almost impossible in a world where even the best actions may have some harmful results. The principle of double effect offers a more reasonable method of analysis for those conflict situations where avoiding harm would require no action, including actions that may be both morally good and necessary for achieving the good. It is important to note that, while nonmaleficence refers to doing no harm, nonmalevolence refers to not intending or willing harm. It may be helpful to think of nonmaleficence not simply as "doing no harm," but as "doing no evil," which is closer to its etymological roots.
As a middle principle, the principle of beneficence (and nonmaleficence) is the basis for certain specific moral norms (which vary depending on how one defines "goodness"). Some of the specific norms that arise from the principle of beneficence in the Catholic tradition are: 1) never deliberately kill innocent human life (which, in the medical context, must be distinguished from foregoing disproportionate means); 2) never deliberately (directly intend) harm; 3) seek the patient’s good; 4) act out of charity and justice; 5) respect the patient’s religious beliefs and value system in accord with the principle of religious freedom; 6) always seek the higher good; that is, never neglect one good except to pursue a proportionately greater or more important good; 7) never knowingly commit or approve an objectively evil action; 8) do not treat others paternalistically but help them to pursue their goals; 9) use wisdom and prudence in all things; that is, appreciate the complexity of life and make sound judgments for the good of oneself, others, and the common good.