The ‘truth’ in Martin Heidegger’s philosophy is a fundamental theme. From the very beginning of his intellectual career, Heidegger attempted to give a more fundamental notion of truth, and during his philosophical activity he took various steps in this regard. However, he never ceased from this basic insight that truth is ἀλήθεια (aletheia): the struggle between concealment and disclosure. In addition, Heidegger believes that in Plato’s philosophy, a transformation has emerged in the essence of truth, so that the truth has become Richtigkeit/correctness. According to Heidegger’s view, this transformation is the source of “Seinsvergessenheit/ forgetfulness of being” and this is the source of various forms of subjectivism and nihilism in the modern age. In contrary, Gadamer argued that Plato actually held the fundamental truth of ἀλήθεια, and that Heidegger’s view that Plato’s thought would inevitably lead to the oblivion of being and modern subjectivity is not correct. Gadamer has various strategies to prove his point of view. In this article, we will consider the status of the idea of the good in the theory of Ideas and the notion of dialectic in Plato’s Seventh Letter, and we will try to illustrate along with Gadamer that there are possibilities in Plato’s thought that can eradicate him from Heidegger’s critique.