Each of the major engineering societies has its own code of ethics. Seven “common core” clauses and several code-specific clauses can be identified. The paper articulates objections to and rationales for two clauses that raise controversy: do engineers have a duty to provide pro bono services and/or speak out on major issues, and to associate only with reputable individuals and organizations? This latter “association clause” can be justified by the “proclamative principle,” an alternative to Kant’s universalizability requirement. At the heart (...) of engineering codes of ethics, and implicit in what it is to be a moral agent, the “proclamative principle” asserts that one’s life should proclaim one’s moral stances. More specifically, it directs engineers to strive to insure that their actions, thoughts, and relationships be fit to offer to their communities as part of the body of moral precedents for how to be an engineer. Understanding codes of ethics as reflections of this principle casts light both on how to apply the codes and on the distinction between private and professional morality. (shrink)