P. A. Schilpp's 'Library of Living Philosophers' is the series which introduced to the philosophical community the format of a volume of essays on the work of a distinguished philosopher, combined with replies to the essays by the philosopher targeted. The format proved attracti ve to a discipline which has always placed a high premium on debate. But the Schilpp series has shown itself unenterprising in its choice of subjects, concentrating on end-of-year reports on philosophers who are of undoubted distinction, but whose contribution to the subject can be regarded as rather definitely over. Which leaves a gap, which the present series is designed to fill, for volumes of a similar format aiming at assessment of philosophers who have distinguished themselves already by making a substan tial impact on their discipline, but whose further work too is awaited with eager anticipation. Michael Dummett is an ideal subject for a series with this goal of mid term assessment. His writings to date have permanently altered philosophy's conception of what is at issue between realism and idealism (and its paler cousin, anti-realism); and this has been achieved by way of a supplementary clarification of a host of issues in the philosophy of language and of mathematics, and of the Frege/Wittgenstein historical tradition from which such issues are typically approached in contemporary philosophy.