Being-in-a-world

When Heidegger insists that we are being-in-the-world, it means that there is no presuppositionless starting point. When Descartes wrote his Meditations, he was already writing.

[O]ne of the presuppositions that escaped Descartes' notice when he set out to put everything in doubt, when he tried to clear the slate of his consciousness and start out from scratch, was that the entire work of doubt relied upon language. By using a word that he had borrowed from his Jesuit teachers, 'meditations,' he was trying to suggest a kind of inner soliloquy of the soul with itself, a solitary, world-less, naked and - here's the punchline - pre-linguistic contact of the soul with itself. But of course, everything he said, and I mean everything he said, every last word of it, was deeply embedded in the words he used that he had inherited from the Jesuits, and from the scholastic philosphers before them, and from his mother and father, and from the books he had read in school, and so on. [...] As Ludwig Wittgenstein [...] said, there is no such thing as a private language. Wherever Descartes starts his Meditations, it will be in the middle of a public language. (Caputo, Philosophy and Theology 46.)