A reader's companion
A theme in the papers
The Federalist Papers on Separation of Powers
Montesquieu, "parchment barriers," and ambition set against ambition.
Everyone agreed the branches of government should be separate. The harder question was how to keep them that way, since a line on paper does not stop an ambitious legislature or executive from crossing it.
These three essays give the answer. Madison starts from the principle, shows why stating it is not enough, and then lays out the design that actually holds: give each branch the means and the motive to check the others.
Federalist No. 47: Separation of Powers
Madison defines the principle: piling all powers in one set of hands is "the very definition of tyranny."
Federalist No. 48: Why Parchment Barriers Fail
Why written lines between the branches are not enough — "parchment barriers" fail without real checks.
Federalist No. 51: Checks and Balances
The mechanism that makes separation work: each branch armed to resist the others.