The Abstractiones is a work in medieval logic from the second half of the 13th century. Clearly a product of the British university culture and much cited, quoted and imitated, it is attributed in two manuscripts to ''Master Richard the Sophist''. This Richard is referred to by other philosophers and logicians as ''The Master of Abstractions'' - an honorific title which indicates that his work was a standard textbook. The Abstractiones is a collection of sophismata, or logical puzzles of increasing complexity and difficulty which have been gathered under logical operators like ''all''. Each sophisma is introduced by a proposition that appears to be both provably true and provably false, like ''God knows whatever he knew''. The Master determines the truth or falsity of the proposition and analyses the defects of the arguments that have been offered by detecting logical fallacies, equivocal expressions and the like. The work as we have it is clearly the result of a process of development, modification, and interpolation, probably extending over at least a generation. Although there came to be works that imitated the Abstractions and followed some of its plan and style, these are ''descendants,'' rather than variations.The Abstractions gives us a better sense than does an independent and original work of medieval logic like William of Ockham''s Summa Totius Logicae of how instruction in techniques of argumentation and reasoning, often of a fairly sophisticated sort, was carried on in British universities in the latter part of the 13th century and well into the 14th century.