Final answer:
Federalist 6 does not explicitly argue that commercial republics are unlikely to fight each other; instead, The Federalist Papers emphasize the benefits of a strong federal government in preventing factionalism. Therefore, the claim is False.
Step-by-step explanation:
In Federalist 6, Publius, which was the pen name used by Alexander Hamilton, James Madison, and John Jay when writing The Federalist Papers, does not specifically argue that commercial republics are unlikely to fight each other. Rather, the essays in general advocate for the merits of the proposed United States Constitution and the formation of a strong federal government. The belief that republicanism and a strong federal government would safeguard against factions and maintain peace and union is a central theme in these essays, especially in Federalist 10, written by Madison. That essay focuses on how the proposed large federal republic would prevent the rise of tyrannical factions due to the diversity of interests and parties within it. Hence, the claim in the question does not precisely reflect the arguments made in Federalist 6 or the Federalist Papers as a whole. Therefore, the statement that Publius argues that commercial republics are unlikely to fight with each other is False.