Rationality Quotes - June 2009
It's not "blatantly false". To get from theory to practice you have to add to the theory various pieces of information about the practical issue. E.g. you might have a general theory of economics, but as a businessman you also have to consider the local details (which are not part of the general theory).
The general theory might tell you (in the best case scenario) what information you need to gather (e.g. Newtonian mechanics tells you that in order to solve specific problems you have to know the force and measure position and velocity at a given time), but even so, you still need to gather that information. So the relationship between theory and practice is not reversible: you may have a general theory and yet be unable to solve specific problems (as you lack the specific information - e.g. meteorology), or you may be able to solve specific problems but lack a general theory (e.g. psychology).