Heidegger's philosophy of logic

This dissertation interprets Heidegger's philosophy of logic, presented in Being and Time and surrounding works, by tracing its historical development against the background of late 19th and early 20th century neo-Kantian logical idealism. Logical idealism turns Kant's transcendental logic into a complete reduction of all cognitive content to a system of logical categories and rules of synthesis, grounded in a pure subject. Heidegger's philosophy of logic argues that such a complete reduction must fail. Logic, he claims, is conditioned by the temporal structure of everyday life. Categories and rules of synthesis are products of the underlying unity of the horizon of time. The same temporal structure enables pre-propositional concrete awareness. Logical structures and concrete experience, therefore, are equally originary: neither can be reduced to the other. On the one hand, this insight allows for the possibility of logically analyzing scientific knowledge, Heidegger believes that such conceptual clarification is productive and important. On the other, logical analysis can not grasp the full significance of experience. Logic, then does not fully explain the nature and origin of knowledge. The task of hermeneutic phenomenology is to provide this ontology by elaborating the structure of temporality.;By deriving the possibility of logic from temporality, Heidegger sets limits on the meaningful application of logic and, at the same time, establishes its objective validity within those limits. This arguments can be extended to formal logic, by providing derivations of formality, propositional form, and inferential validity from temporality. Heidegger's position, then, affirms the validity of formal logic, while maintaining that its structures are capable of a more fundamental articulation. The ontology of everydayness provides this foundation and grounds logic. Finally, I show that the systematic structure of Being and Time is shaped by the dictates of traditional logical systems, even while Heidegger develops a hermeneutic phenomenology that makes this traditional structure irrelevant. This insight partly answers why Heidegger did not complete the projected divisions of Being and Time and also makes sense of the apparent conflict between its systematic and ethical views.