such, finds its culmination and ultimate verification in the ethical world, which essentially consists in the realization of ends. Trendelenburg's Naturrecht [the right of nature] may, therefore, be taken as in a manner the completion of his system, his working out of the ideal as present in the real. The ethical end is taken to be the idea of humanity, not in the abstract as formulated by Immanuel Kant, but in the context of the state and of history. Law is treated throughout as the vehicle of ethical requirements. In Trendelenburg's treatment of the state, as the ethical organism in which the individual (the potential man) may be said first to emerge into actuality, we may trace his nurture on the best ideas of Hellenic antiquity. Fischer–Trendelenburg debate In 1865 he became involved in an acrimonious controversy on the interpretation of Kant's doctrine of space with Kuno Fischer, whom he attacked in Kuno Fischer und sein Kant (1869), which drew forth the reply Anti-Trendelenburg (1870). The controversy became known in the history of philosophy as the Fischer–Trendelenburg debate. Trendelenburg's position on the debate (the position that "Kant may establish that space and time are a priori and intuitive conditions for experience in the "Transcendental Aesthetic," but this in no way entails that space and time have nothing to do with the objects outside of possible experience") has been variously dubbed as "Neglected Alternative," "Trendelenburg's gap" [die trendelenburgische Lücke], "Pistorius's gap [die pistorische Lücke]" (named after Hermann Andreas Pistorius), or "third possibility" [die dritte Möglichkeit]. Family His son, Friedrich Trendelenburg, was a prominent surgeon; several medical techniques and matters are named for him. Works (selection) Trendelenburg was also the author of the following: Elementa Logices Aristotelicae (1836; 9th ed., 1892; Eng. trans. 1881), a selection of passages from the Organon with Latin translation and notes, containing the substance of Aristotle's logical doctrine, supplemented by Erlauterungen zu den Elementen der Aristotelischen Logik (1842; 3rd ed., 1876). Logische Untersuchungen (Logical Investigations), 2 vols. (1840; 3rd ed. 1870), and Die logische Frage in Hegels System (1843), important factors in the reaction against Hegel. Historische Beitrage zur Philosophie (1846–1867), in three volumes, the first of which (Geschichte der Kategorienlehre) contains a history of the doctrine of the Categories. Geschichte der Kategorienlehre I: Aristotle Kategorienlehre; II: Die Kategorienlehre in der Geschichte der Philosophie (1846, reprint: Hildesheim, Olms, 1979). Des Naturrecht aufdem Grunde der Ethik (1860). Lücken