If knowing is to be possible as a way of determining the nature of the present-at-hand by observing it, then there must first be a deficiency in our having-to-do with the world concernfully. When concern holds back from any kind of producing, manipulating and the like, it puts itself into what is now the sole remaining mode of Being-in, the mode of just tarrying-alongside. In this kind of 'dwelling' as a holding-oneself-back from any manipulation or utilization, the perception of the present-at-hand is consummated.

"one who runs along with" but the equivalent meaning in English is closer to "bandwagon effect" or "herd instinct" standing for the notion that people often do and believe things merely because many other people do and believe the same things) of National Socialism and no punitive measures against him were proposed. Within philosophy it played a crucial role in the development of existentialism hermeneutics deconstructionism postmodernism and continental philosophy in general. One crucial source of this insight was Heidegger's reading of Franz Brentano's treatise on Aristotle's manifold uses of the word "being" a work which provoked Heidegger to ask what kind of unity underlies this multiplicity of uses.

As a solution to this condition Heidegger advocated a return to the practical being in the world allowing it to reveal or "unconceal" itself as concealment. Finding ourselves "always already" fallen in a world of presuppositions we lose touch with what being was before its truth became "muddled". Writing extensively on Nietzsche in his later career and offering a "phenomenological critique of Kant" in his Kant and the Problem of Metaphysics Heidegger is known for his post-Kantian philosophy.