The present book is the third in a series of collaborations, its two predecessors being:

• • Beyond Sets: A Venture in Collection-Theoretic Revisionism (Frankfurt: Ontos Verlag, 2010).

• • Reflexivity: From Paradox to Consciousness (Frankfurt: Ontos Verlag, 2012).

In this book, as in the others, a key philosophical concept (collectivity/totality, reflexivity/self-orientation, and in this case categoricity/sortalization) is subject to critical scrutiny and innovative exploration.

A great deal of water has flowed under the philosophical bridge since the tract on The Conception of Types in the Light of the Modern Logic (Der Typusbegriff im Lichte der Neuen Logik) by Carl G. Hempel and Paul Oppenheim (Leiden, 1936). This classic venture at renovating categorization in the heyday of logical positivism was predicated on now-outdated perspectives and requires updating in the wake of the wider horizons that subsequent philosophizing has opened up. The present deliberations represent an attempt to accommodate these broadened perspectives.

The authors are grateful to Estelle Burris for aid in preparing their text for publication.