Having just finished reading Greg Shirley’s recently published book, Heidegger and Logic, I wanted to jot down a few thoughts before they disappear into the fog as I read the next book, and the next one after that. There are numerous strengths in this book. There are the obvious, headline contributions of offering a detailed account of Heidegger’s writings on logic during the Being and Time period, and thereby addressing the charges of those (beginning with the Logical Positivists) who accused Heidegger of being an irrationalist. In addition, what stood out for me was Shirley’s defense of Heidegger against Ernst Tugendhat’s criticism – at least for me it provided a key to connecting the various different arguments of the book. Tugendhat’s criticism, in brief, is that while Heidegger claims that ‘Before being discovered Newtonian laws were neither true nor false’, Heidegger nonetheless claims that these laws are uncovered as universal laws and hence as transcending, as Shirley puts it, ‘any particular instance of uncovering.’ Put in other words, for Shirley Tugendhat accuses Heidegger of not allowing for the ‘possibility that judgements/assertions may exhibit more or less rational justification, and so may more or less correspond to an object.’ (75-6) In short, on Tugendhat’s reading Heidegger fails to distinguish between, or cannot distinguish between, aletheia and apophansis.
For Shirley, however, Tugendhat’s reading of Heidegger reflects a continued adherence to Kantian epistemology whereby knowledge, as Shirley puts it, ‘is asymptotic: regulative ideas perhaps guarantee that absolute knowledge may ever be approached, while the finitude of discursive reason guarantees that it is never actually achieved.’ For Shirley, however, ‘Heidegger has an asymptotic conception of falsity as well: absolute error may be approached but never actually achieved, since even error presupposes that a minimum of intelligibility has been uncovered about which one may prevaricate or otherwise assert a falsehood.’ (76). In other words, the uncovering of an entity discloses this entity just as it is in itself, even if, owing to Dasein’s temporal and spatial finitude this uncovering is in turn ‘always only a dimension or aspect of the thing itself.’ By maintaining an asymptotic approach to both truth and falsity, Heidegger is able to maintain the distinction between aletheia and apophansis.
Following through on his arguments concerning the ‘minimum of intelligiblity’ that is uncovered, Shirley is able to argue quite convincingly that Heidegger’s thought is not only able to accommodate formal, inferential logic, but moreover he is able to justify this logic independently (in contrast to Leibniz, for example) by showing that the logical ground that is stated in a principle (such as the principle of sufficient reason) ‘is simply [the] verbal articulation of something that precedes all assertion and makes all assertion possible in the first place, the temporal structure of being-in-the-world.’ This structure is revealed as it is, but as being-in-the-world it is implicit and requires an abstraction from context in order to make explicit the inferential, consequential structures of being-in-the-world, and hence logic and logical principles. What is distinctive about logic is that the object that is uncovered, and uncovered just as it is and with a ‘minimum of intelligibility’ that provides normative strictures upon how the thought of this object ought to proceed, is thought itself. Heidegger is clear on this point, as Shirley cites Heidegger:
Thinking taken as thinking about something, with any subject-matter, is formal thought, in contradistinction to material, content-relevant thought. This formal thinking is not without an object, but is very much object-oriented, though neutral with respect to content. General logic, as knowledge of formal thinking, is thus formal logic. (Metaphysical Foundations of Logic, 1984 , 33; cited by Shirley, 93).
In the final chapter of Shirley’s book he shows how Heidegger’s thought can equally provide an understanding of the grounds of contemporary logic. All in all, an excellent book and one I’ll return to often.