Having written my masters thesis on adjectival semantics in Montague Grammar many years ago, I very much looked forward to reading Kees van Deemters book. And I was not disappointed. He manages to explain very convincingly "what the fuss is about": where it is we meet vagueness and why it is that it is an advantage and a necessity in dealing with the world, both scientifically and on a day-to-day basis. He also gives a very gentle explanation of the rather dense linguistic, logical and philosophical theories that underpins this area, without the resulting picture being in any way oversimplified. I can highly recommend this book for both the general "uneducated" reader and academics in linguistics, mathematics, philosophy, logic and computer science. ( )

The limits of technology are philosophical. The challenge, according to Van Deemter, is to come to terms with our inability to know anything with certainty. Boolean logic restricts reality to two alternatives, true or false, and is unable to deal with gradations or subtle changes. Because most objects in the world are not clearly distinct, and because conditions are contingent and events must be situated in a context, boundaries and measurements are always vague. Language and mathematics can reflect vagueness, and fuzziness, supervaluation and penumbral connections can model vagueness, but we cannot avoid it.

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A book in praise of vagueness that begins with an epigraph from Robert Musil, describing the weather? Count me in.

Van Deemter engages language, mathematics, psychology, computer science and literature in this exploration of vagueness and the models developed to mimic vagueness in the quest for Artificial Intelligence. He begins with the Sorites Paradox—when does a collection of stones become a heap?—then launches into a discussion of how the either/or dichotomies of classical logic are inadequate as a basis for the scientific enterprise. The problem is that most indicators are gradable rather than “crisp,” whether the referent is species, temperature, length, intelligence or culture. Not every difference is a step change, or a change in kind. Quantitative adjustments—like the mathematical theory of computational complexity—remove vagueness while introducing a certain arbitrariness, and qualitative reasoning captures regularities but suppresses details. Alas, a machine cannot translate a poem.

Science counts on the hedge, the qualification, the exception. Scientific theories are, at best, approximations of the facts. Thinking about the world in crisp, Boolean terms may be justified, writes Van Deemter, but such simplifications often produce false clarity that can cause misinformation. It may now be necessary, he concludes, to invent new ways of thinking about truth, meaning, and communication. ( )

Interesting book that gives readers an idea about what vagueness is, how it functions and how/why we use it. The subject is treated from different points of view (linguistic, logical, mathematical, philosophical, ...) It's not an easy read: some sections are more difficult to grasp than others, especially the theories of vagueness in the second part. It's not a compelling book, and at times rather tedious, but still interesting enough to keep one's attention going. ( )