Tractatus Logico-Philosophicus
Ramsey showed that it is possible to reformulate the definition of "predicative" by using the definitions in Wittgenstein's Tractatus Logico-Philosophicus. As a result, all functions of a given order are "predicative", irrespective of how they are expressed. He goes on to show that his formulation still avoids the paradoxes. However, the "Tractatus" theory did not appear strong enough to prove some mathematical results.