Heidegger on Logic

Heidegger on Logic J. N. MOHANTY Why should one write on Heidegger's understanding of logic? After all, Heidegger was not a logician, nor did he do philosophy of logic. Indeed, there is no justification for expecting of any great philosopher whatsoever that he should have views, and reasonably plausible views, about the nature of logic or on specific themes belonging to the domain of logic. A moral philosopher may totally bypass any concern with logic, without detriment to his thinking. As an existentialist philosopher, Heidegger could have done that, and much of his Dasein-analytic would yet have retained its value. But Heidegger was also an ontologist, and was deeply concerned, all his philosophical career, with metaphysics and with the various questions about the nature of thought and of being. These concerns, to say the least, bring him to the proximity of logic as it had been understood in the tradition going back to Aristotle. And, as a matter of fact, Heidegger's own access to the problems of ontology and metaphysics has been determined by his reflection on logic. Two claims may therefore be advanced. First, it is not unreasonable , and what is more important, not unfair to Heidegger, to enquire into his understanding of logic. Secondly, his reflections on logic may help us to gain a better understanding of his overall philosophical interests than would be possible otherwise. Even if he was not a logician he was concerned with the nature of logic, and with some central problems belonging to the domain of logic. This concern begins with his doctoral work on the problem of psychologism in theory of judgment, ~continues in the habilitation work on ' Die Lehre vom Urteil ira Psychologisraus. Ein kritisch-positiver Beitrag zur Logik. Dissertation, FreiburginBr., 19x3.Reprinted inMartinHeidegger,Gesaratausgabe,Bd. 1,FriiheSchriften (FrankfurtamMain :Klostermann,1978).FurthercitationstoGesamtausgabeareabbreviatedasGA. The reader is referred to the followingsecondary literature on this topic: Thomas A. Fay, Heidegger: The Critique of Logic (The Hague: Martinus Nijhoff, 1977).Reviewedby the present author in The SouthwesternJournal of Philosophy, XI, (198o): 174-79; WalterBr6cker,"Heidegger und die Logik,"PhilosophischesRundschau I (t953-54): 48-56; AlbertBorgmann,"Heideggerand SymbolicLogic,"in M. Murray, ed., Heidegger & Modern Philosophy(NewHaven:YaleUniversity Press, t978), 3-22. [1o7] 108 JOURNAL OF THE HISTORY OF PHILOSOPHY 26:1 JANUARY 1988 the semantic categories in Duns Scotus,2 and reaches its maturity in the Marburg lectures of 1925-28.3 In this essay, I will deal with three topics. In the first section, I will try to determine how Heidegger understood the nature of logic. In the second section, I will consider the one problem of logic to which he devoted a great deal of attention: the theory of judgment. In the third section, I will look into how his concern with logic opens up for him several paths to go beyond logic. At the end, I will reflect on this entire account, not so much to find faults with Heidegger's understanding of logic, as to determine its precise nature and limitations. 1. NATURE OF LOGIC A. A Preliminary Definition. One commonly held view of the nature of logic, in the traditional accounts, is that logic is a normative science of thought, whose aim is to lay down those rules which one ought to follow if one aims at truth. This account may be faulted on various grounds. First of all, 'thought' is ambiguous, referring both to the process of thinking and the content of thinking. Of these two, the former belongs to the field of psychology. If the content of thinking is understood in the sense of objective meanings or structures of meaning, propositions or configurations of them, then only logic may be said to be concerned with them. Why then is logic to be still regarded as a normative science? Of course, once there is a logical law to the effect 'If p implies q, and p, then q' (where p and q are propositional variables), then it does follow that if a person believes in a proposition 'A implies B' and also believes that A (where 'A' and 'B' are names of propositions), then he also ought to believe that B. But such a normative demand on...