Chapter 1 demonstrates that a key argument in justifying the establishment of the free state was the claim that the people or their representatives were entitled to alter the form of government. Earlier historians had paid no attention to this argument. The chapter first discusses the emergence of this argument in pre-revolutionary England and then traces its development in the 1640s. The question of the people’s, or their representatives’, right to change the form of government was thrown into sharp relief in late 1647 when the Levellers put forward their proposal for a novel constitution. The question was discussed in the famous Putney debates, and an argument for the right to alter the constitution was widely advanced from the autumn of 1648 onwards. It was based on the idea of popular sovereignty, that all public authority emanated from the people and that whoever exercised that authority only held it by trust. Some protagonists argued that the people could change the form of government when the king forfeited his trust, but many others insisted more radically that the people could do the same whenever they so wanted.