Final answer:
Thomas Paine's pamphlet, Common Sense, effectively convinced ordinary colonists to support independence from Great Britain by using simple language to express plain arguments for a republican government and by critiquing the monarchy, particularly King George III.
Step-by-step explanation:
Thomas Paine convinced ordinary colonists to side with the Patriot cause of independence by publishing his influential pamphlet, Common Sense. Paine utilized simple language that appealed to ordinary people, articulating plain arguments and common sense about the need for the American colonies to seek independence from Great Britain. He rejected the idea of monarchy, specifically calling King George III a 'royal brute', and promoted the establishment of a republican form of government in America, where citizens would exercise popular sovereignty and where the government's duty was to the people, not a hereditary ruler.
Paine's writing resonated with colonists who were already feeling the strain of British rule and helped them to see that continued allegiance to Britain was at odds with their own interests and the natural rights of equality espoused by Enlightenment thinkers. By covering both the economic injustices and the higher principles of self-governance, Common Sense appealed to a broad audience and played a crucial role in shifting public opinion in favor of independence, which was formally declared on July 4, 1776, with the adoption of the Declaration of Independence.