Quora Answer: What are Heidegger’s most interesting ideas?
Heidegger has so many interesting ideas that it is almost impossible to enumerate them. Heidegger has become an indispensable to philosophy. We know now that some of his essential ideas that seemed novel came from Husserl, but he had so many ideas of his own that this does not take anything away from Heidegger’s contribution.
For me the most interesting ideas in Being & Time is the difference between Present-at-hand and Ready-to-hand modes of being-in-the-world of Dasein.
Also there is the existentialia structure of Dasein itself.
We have to understand that Heidegger is operating within the Kantian episteme and is answering questions that arose in the philosophy of Husserl. But in order to distinguish himself from his teacher he is going back to Aristotle and Hegel’s phenomenology in order to distinguish himself from Husserl’s phenomenology. Husserl expected him to be a close follower, but instead Heidegger developed his own approach by concentrating on Ontology rather than Phenomenology.
The best thing to do is to read commentaries on Heidegger. There are not commentaries on almost every aspect of his philosophy so it is fairly easy to find out about it, and find the part of it that interests you.