The equal formal freedom that the rightful state sustains according to the Kantian doctrine can be regarded as a species of formal equal opportunity. If the Kantian doctrine of right can be defended, then we have good grounds to uphold a version of formal equal opportunity without being under normative pressure of good reasons to go further and embrace any substantive equal opportunity doctrine. In a nutshell, the Kantian claim will be that embracing more expansive notions of equal opportunity, substantive equal opportunity or the yet more expansive luck egalitarian family of doctrines, will prove incompatible with maintaining formal equal freedom for all and with sustaining the condition in which no adult person is the master of any other (if substantive equality is sustained, then some people are being forced to use their persons and forced to suffer their property being used for the private purposes of others—a fundamental violation of right). This may be one of those argumentative standoffs in which, as Brian Barry once remarked, one man's reductio ad absurdum is another's Quod Erat Demonstrandum. (For Kant's views on equal freedom and the doctrine of right, see Guyer 2000 and Ripstein 2009). For more on Kantian moral and political philosophy, see other entries in this Encyclopedia. 