Amongst those to argue for the first option was Sir Robert Filmer argued that the obligation to obey the sovereign was, like the obligation to obey one’s parents, simply a natural fact. To disobey was to go against nature, and against God, who created nature in this particular way. Natural obligations towards a divinely appointed King provided the basis for government and authority.

But, especially from the middle of the seventeenth century onwards, these sorts of explanation became viewed with increasing scepticism. First Hobbes, then Locke, reflected on the troubled years in the middle of the century, and concluded that a different basis for governmental authority had to be argued out.

In place of a notion of natural and God-given hierarchy, they started from an assumption of freedom and equality amongst (usually male, white, property-owning) human beings. They asked how these individuals could put themselves under an authority. The answer – by agreeing amongst each other to do so. This answer meant that the limits of governmental power were set by the original agreement. In Hobbes’ case, these limits were virtually non-existent: he thought that we would contract together to hand over nearly all our rights to a virtually absolute monarch. In Locke’s case, the power handed over was much more limited. But whatever the end result, the method of getting there was similar. The philosophers asked themselves, what sort of agreement would be reached by people thinking very carefully and rationally about the arrangements under which they would live. This agreement is the social contract.

If a group of people were to set up an island community they would have to make some decisions – about dividing up the work, about organising living spaces and so on. It seems very likely that early on these people would have some sort of island meeting, to thrash out a set of rules to govern these activities - maybe to appoint a leader. There would be decisions to be taken – who is to be leader, and decisions about decisions – how are we to decide who is to be leader? This idea of free individuals coming together, and thrashing out a set of rules is the idea behind a social contract.

The idea is a very ...