A tax on tea seems a small thing to fight a war over. The colonists did not think they were fighting over money. They thought they were defending liberty itself, and they drew on several streams of thought to explain why. Historians still argue about which stream mattered most, but all of them helped turn grievances into a cause.

The rights of Englishmen

Colonists began not as revolutionaries but as defenders of an inheritance. They saw themselves as heirs of Magna Carta, of the Parliament that had resisted the Stuart kings, and of the Glorious Revolution of 1688, which had driven out James II and produced the English Bill of Rights. A central principle of that tradition was that subjects could be taxed only with the consent of their representatives. Patriots argued that they were simply asking for the same rights Englishmen enjoyed at home.

Locke and consent

The philosopher John Locke, in his Second Treatise of Government, published in 1689, argued that people create governments by consent in order to protect their lives, liberties and property. A government that betrays that trust forfeits its claim to obedience. Patriots used Locke mainly to justify resisting a government that had broken its trust, and his language echoes through their pamphlets. Locke wrote that "the end of law is not to abolish or restrain, but to preserve and enlarge freedom." Historians in the twentieth century once treated the Revolution as almost purely Lockean. Later scholars found that colonists quoted Locke less often than they quoted another tradition.

Republicanism and the fear of power

That tradition is usually called republicanism. Drawing on Rome, Renaissance Italy and English critics of the court, it taught that liberty was fragile and survived only where citizens had virtue, meaning a readiness to put the common good above private gain. Power was always grasping at liberty, and its favorite tools were corruption, debt, placemen and standing armies. Colonists devoured Cato's Letters, essays by John Trenchard and Thomas Gordon warning against power and corruption, first printed in London in the 1720s.

The historian Bernard Bailyn argued in the 1960s that this outlook shaped how colonists read events. In Bailyn's account, colonists came to see British measures as a deliberate plot against liberty, so that each tax and each regiment looked like a step in a design rather than a separate blunder. Critics reply that ministers in London were often muddled rather than scheming, which is exactly Bailyn's point: belief in the plot was real even if the plot was not.

Religion

The revivals of the Great Awakening in the 1730s and 1740s had taught many colonists to question established authority and trust their own judgment. Dissenting Protestants dreaded rumors that the Church of England would send a bishop to America. As early as 1750 the Boston minister Jonathan Mayhew delivered a famous sermon arguing that resisting tyrants could be both lawful and godly.

The British view: sovereignty cannot be split

Britain had its own powerful theory. The jurist William Blackstone, in his Commentaries on the Laws of England of the 1760s, held that every state must have a final authority, and in Britain it was the king in Parliament. Blackstone taught that sovereignty had to be supreme and undivided. If colonial assemblies could refuse Parliament's laws, then two supreme powers would exist in one empire, which seemed absurd. Colonists slowly worked toward the alternative that the empire might be a union of separate legislatures joined only through the king. That idea later became the British Commonwealth, but in 1775 few in London could accept it.

Common Sense

Until 1776 most Patriots blamed wicked ministers and appealed to a good king. Thomas Paine, an English corset maker and excise officer who had arrived in Philadelphia in late 1774, changed the argument. His pamphlet Common Sense, published in January 1776, attacked the king and hereditary monarchy itself, not just bad advisers. "There is something very absurd," he wrote, "in supposing a continent to be perpetually governed by an island." He promised that "the cause of America is in a great measure the cause of all mankind." It sold tens of thousands of copies within months.

Not everyone was persuaded. The Anglican clergyman Charles Inglis answered in The True Interest of America Impartially Stated, warning that independence would bring war, ruin and anarchy, while reconciliation could still win the colonists their rights.

Worked example: one regiment, three readings

Take the British regiments stationed in Boston from 1768. A reader schooled in the rights of Englishmen noted that the English Bill of Rights forbade a standing army in peacetime without Parliament's consent, and asked why colonial assemblies had not consented. A republican reader saw the classic tool of tyranny: soldiers paid by taxes the people never approved, quartered among them to cow them. A minister might preach that a free people answered to God before any king. A British official, reading Blackstone, saw something else entirely: lawful troops sent by the sovereign legislature to protect officials from mobs. Each reading rested on a coherent theory. The conflict grew so hard to settle partly because both sides were reasoning carefully from different first principles.