Human rights are a product of a philosophical debate that has raged for over two thousand years within the European societies and their colonial descendants. This argument has focused on a search for moral standards of political organization and behaviour that is independent of the contemporary society. In other words, many people have been unsatisfied with the notion that what is right or good is simply what a particular society or ruling elite feels is right or good at any given time. This unease has led to a quest for enduring moral imperatives that bind societies and their rulers over time and from place to place. Fierce debates raged among political philosophers as these issue were argued through. While a path was paved by successive thinkers that lead to contemporary human rights, a second lane was laid down at the same time by those who resisted this direction. The emergence of human rights from the natural rights tradition did not come without opposition, as some argued that rights could only from the law of a particular society and could not come from any natural or inherent source. The essence of this debate continues today from seeds sown by previous generations of philosophers.
The earliest direct precursor to human rights might be found in the notions of `natural right' developed by classical Greek philosophers, such as Aristotle, but this concept was more fully developed by Thomas Aquinas in his Summa Theologica. For several centuries Aquinas' conception held sway: there were goods or behaviours that were naturally right (or wrong) because God ordained it so. What was naturally right could be ascertained by humans by `right reason' - thinking properly. Hugo Grotius further expanded on this notion in De jure belli et paci, where he propounded the immutability of what is naturally right and wrong: