The article presents Martin Heidegger's early conception of foundational questions of logic and science. It focuses on their treatment in the Introduction to Phenomenological research (the lectures from 1923/1924, published as Gesamtausgabe, Bd. 17). Presenting the conception of phenomenon, perception, language/speech, noun and verb, proposition and deceit, the article shows the fundamental idea of facticity of speaking as the ground of these questions. It uses ideas of existence, fact and time to achieve the result. The impact on the most famous early book by Martin Heidegger is also considered.
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