One fundamental way in which the anti-federalists and federalists were similar is that they

Both Federalists and Anti-Federalists believed that people were ruled by self-interest, and that it was the  government's jobs to regulate the less savory aspects of human nature. Both parties regarded personal rights and freedoms highly, and thought government should be constructed in a manner that those in power would be unable to use said power for their own interests.

He gathered information from primary sources.