Final answer:
The Anti-Federalists agreed to ratify the Constitution after the Federalists promised to include a Bill of Rights that would protect individual liberties against potential government abuse.
Step-by-step explanation:
The promise that encouraged Anti-Federalists to ratify the Constitution was the inclusion of a Bill of Rights. The Anti-Federalists were concerned about the potential for the federal government to abuse its power and the lack of explicit protections for individual liberties.
The Federalists, who favored a strong central government, agreed to add a Bill of Rights to the Constitution to alleviate these concerns and secure the necessary support for ratification. This compromise was crucial, as the large and influential states of New York and Virginia only narrowly approved the Constitution, and states like North Carolina and Rhode Island refused to ratify until the Bill of Rights was promised.
The addition of the Bill of Rights allowed the Federalists to argue that they had considered the Anti-Federalists' requests for protecting people's liberties. Despite concerns that the amendments did not thoroughly address issues such as the judiciary and direct taxation, they were pivotal in gaining the support of many Anti-Federalists and securing the widespread ratification of the Constitution by the states.