The chapter begins by showing the facticity of vulnerability in different situations of life. Then, it asserts, as do authors such as Williams, Nagel, MacIntyre or Nussbaum, that western ethics has relegated the vulnerable nature of individuals and has brought to the fore the ideal of self-sufficiency, autonomy, will of power or of agency, when sketching models of good life. But, going beyond that, the question asked, in a third stage, is how to establish a foundation for the moral obligation of protecting vulnerable beings as a requirement of justice, and the chapter presents three relevant answers. Firstly, an ethics of care in the tradition of Hyginus, Heidegger, Boff and the Ethics of Earth, but also based on neuro-scientific and evolutionary biology studies, such as those of Churchland. Secondly, an ethics of responsibility, as proposed by Jonas, and by discourse ethics in the version of Apel and Habermas, underlining the differences between them. And finally, an ethics of cordial reason, which is a warm version of discourse ethics.