After decades of philosophical research at institutions such as the University of Canterbury, the London School of Economics, and the University of London, he was knighted in 1965.  
This philosopher defined quantitative verisimilitude by means of the formula Vs(a)= CtT(a)-CtF(a), where a is a given statement. With regard to the philosophy of science, he believed that the central problem was that of demarcation. Accepting the Humean critique of induction made this author of The (*) Logic of Scientific Discovery unique among his contemporaries regarding the problem of induction. Because of his rejection of induction, he proffered a theory of falsifiability to account for the problem of demarcation. This author of The Poverty of Historicism held views on epistemology that were based in the idea that knowledge is gained in the presentation of problems and humans' ability to solve them. After decades of philosophical research at institutions such as the University of Canterbury, the London School of Economics, and the University of London, he was knighted in 1965.  For 10 points, name this author of The Open Society and its Enemies. 
This philosopher defined quantitative verisimilitude by means of the formula Vs(a)= CtT(a)-CtF(a), where a is a given statement.
Karl Popper