Haha, no. When I say Rationalist I mean it in the philosophical sense, i.e. that the Universe has an underlying logical structure, and any of its properties can be deduced with reason. In the old days, it was opposed to Empiricism, which basically argues that we can only learn about the Universe...
I am trying to establish a Rationalist approach to Physics as a side project, and have taken Hamilton's Principle as one of the few postulates in my work. I've developed the concept enough to arrive at the usual stuff, like the Euler-Lagrange equations, Newton's First Law and Nöther's Theorem...