In the contribution, I explore some of the value-based foundations of social security, i.e. foundations of social security and social assistance schemes, deriving them from three selected theories of political philosophy: liberalism, libertarianism and communitarianism. The three theories are briefly accompanied by the theory of utilitarianism, in the contribution limited to the notion economic efficiency. Relying on the theories’ hallmarks, I address the notions of social solidarity, property and freedom (of conduct) as three commonly conflicting elements linked to the legal framework of every social protection scheme. By doing so, I try to show how arguments stemming from political philosophy can be used in order to morally affirm, legitimize or invalidate particular institutions or regulatory elements regarding social security. If used by courts or the legislator, they can offer guidance in bringing about changes to the (use or development of) social security legislation. Different arguments can be used in order to achieve different, even diverging goals, e.g. broadening or limiting personal or material scope of coverage, increasing or decreasing the level of benefits, enhancing or diminishing the role of private insurance. [PAR] The discussion is based upon a generalized or textbook model of Bismarckian social insurance and tax-funded social assistance schemes with universal, tax-funded social security schemes added to the debate only briefly. Several generalizations also apply to the depiction of key features of the selected theories, since their in-depth analysis would by far transgress the scope of this contribution.