This contribution focuses on Heidegger’s critique of the vulgar nationalism contained in the Black Notebooks (1931-1938), and it follows the rejection of ideologisms that many of his works entail. According to Heidegger’s juridical reflection, “freedom is the ground of the inner possibility of correctness” with which external ideologies such as that of nationalism are avoided. This suggestion contrasts with Heidegger pro-Semitic orientation, testified by his rector’s speech in 1933, but is in line with the distance Heidegger sets between both the moral and the epistemological-ontological world, supported in his writings since the Marburg lectures (1923-1928). In the type of society, Heidegger figures out individuals live together in the πόλις by ek-sisting into the truth of being and by understanding the assignment of those directives that must become their laws and rules. These principles can’t be merely something fabricated by human reason, because they are a) the expression of social thinking made upon a juridical and normative framework close to liberalism. According to Heidegger, humanity is conceived to be free-in and able to choose the avoidance of totalitarian regimes voluntarily, as well as of eternal values supporting ideologies. With the freedom-in concept Heidegger b) solves the problem of coercive violence caused by the restriction of the ought to (i.e. the obligations that come from ideologies) towards the Being, to show the significance of ἦθος in which Dasein is placed. The choice to be in the ἦθος c) provides an explanation based on Heidegger’s critique of technology in his post-Turning writings. This critique clarifies why a national socialist ideology, making use of such technical instruments and supporting ethical materialism, is not in line with the political ontology Heidegger promotes in his writings.