Final answer:
Thomas Paine argues that declaring independence and establishing a republican form of government would guarantee American success.
Step-by-step explanation:
Thomas Paine argues in his pamphlet Common Sense that the guarantee of American success lies in declaring independence from Britain and establishing a republican form of government. He criticizes the monarchy and advocates for a government based on popular sovereignty, where elected representatives govern the state. Paine's pamphlet was popular because it appealed to ordinary people with its simple and direct language, and it helped convince many to reject monarchy and support independence.