Michael Durrant 
Sortals and the Subject-predicate Distinction (2001) [PDF ebook] 

This title was first published in 2001. The problem of the subject-predicate distinction has featured centrally in much of modern philosophy of language and philosophical logic, and the distinction is taken as basic or fundamental in modern philosophical logic. Michael Durrant seeks to demonstrate that the distinction should not be taken as basic or fundamental and argues that the reason for it being held to be fundamental is a failure to acknowledge the category and role of the sortal. A sortal is a symbol which furnishes us with a principle for distinguishing and counting particulars (objects) and whick does so in its own right relying on no antecedent principle or method of so distinguishing or counting. This book explores sortals and their relationship to the subject-predicate distinction; arguing that the nature of sortal symbols has been misconstrued in much modern writing in the philosophy of logic by failing to distinguish sortals from names and predicates.