Natural law refers to an objective set of principles independent of and higher than human law, knowable by human reason and upon which human law is based. In religious terms, natural law refers to the human understanding of divine law or the laws of nature. In non-religious terms, it refers to an objective set of principles necessary for human prosperity which constrain human actions and social arrangements. In either case, natural law is universal and unchanging. Its principles are in accordance with human nature and conducive to human flourishing and are thus binding on human conscience. Some natural law theories argue that human laws that do not to conform to natural law are not rightly called laws; others note that these laws fall short, but allow that they can be called laws nevertheless.