Remember the question of the meaning of being? Well, we’re back to it. That question is only possible if something like an understanding of being already is. An understanding of being belongs to Da-sein.
This section is about the source of a great many philosophical problems. The understanding of being - both ontically and ontologically - initially orients itself to innerworld beings. That’s how being as such is passed over for things that are objectively present. Being = reality. This section has some great stuff about the problems of reality, but I think it’s basically build up to Heidegger’s discussion of truth as aletheia.
The question is, what connection does truth have with being? Heidegger says three things about the traditional concept of truth. First, its traditional position is in the proposition. The judgement. Sentences are where truth “happens.” What truth is, is agreement of the judgment with its object. The correspondence theory of truth. And it was Aristotle that initiated both of these ideas when he created logic.
Heidegger begins his critique of the traditional idea of truth by saying that the concept of “agreement” is entirely general and empty. What exactly this “agreement” is is obscure. It is meant to be a formal relation of the ideal content of the mind to the real thing about which one judges. What corresponds is two ontic things. The content of a statement is related to an object; these are two things that can have a formal relation to one another. What Heidegger ends up saying is that correspondence isn’t so much wrong as it is insufficient. This is the best example of the movement I mentioned at the beginning; the common sense version of truth is taken, and deepened.
Rather than correspondence, truth is aletheia. Disclosure. Truth lets being appear in themselves; a true statement discovers a showing that already existed. Truth is both opening and closure - for example, when you see an apple as an apple, you close off seeing it as a pear.
It might be useful here to recall the three aspects of disclosure - understanding, interpretation and discourse. We exist understandingly; we exist in the truth.
Now, all three of these elements are, initially and for the most part, fallen. They are fallen into publicness. This means that Da-sein is usually disclosed to itself as something that it is not - this is inauthenticity. Because disclosure is fallen, Da-sein is also in untruth. Da-sein is both in truth and untruth.
Constituted by disclosedness, Da-sein is in the truth. There is truth only insofar as Da-sein is. This applies to everything, including something like scientific truths. To say there is eternal truth is not proven until one proves Da-sein is itself eternal.
That's the end of Division I. Eventually I'll do a single post on Division II, which is where the book gets really hard. The three ecstasies of temporality! Anticipatory resoluteness! All that good stuff.