Of the limits to the authority of society over the individual (Chapter IV, paras 1–21)

First, the individual ought not to injure ‘certain interests’ of other people, ‘which, either by express legal provision or by tacit understanding, ought to be considered as rights’ (ibid.). Second, he ought to ‘bear his share (to be fixed on some equitable principle) of the labours and sacrifices incurred for defending the society or its members from injury and molestation’ (ibid.). ‘These conditions society is justified in enforcing at all costs to those who endeavour to withhold fulfilment’ (ibid., emphasis added).