The field of mathematical logic dealing with computability and its generalizations has been called "recursion theory" since its early days. Robert I. Soare, a prominent researcher in the field, has proposed (Soare 1996) that the field should be called "computability theory" instead. He argues that Turing's terminology using the word "computable" is more natural and more widely understood than the terminology using the word "recursive" introduced by Kleene. Many contemporary researchers have begun to use this alternate terminology. These researchers also use terminology such as "partial computable function" and "computably enumerable "("c.e.")" set" instead of "partial recursive function" and "recursively enumerable "("r.e.")" set". Not all researchers have been convinced, however, as explained by Fortnow and Simpson.