Gadamer was born in Marburg, Germany, as the son of a pharmaceutical chemist who also served as the rector of the university there. Gadamer resisted his father's urging to take up the natural sciences and grew more and more interested in the humanities. In the early 1920s he was a student of the neo-Kantian philosophers Paul Natorp and Nicolai Hartmann, and he defended his dissertation in 1922.
Shortly thereafter Gadamer moved to Freiburg and began studying with Martin Heidegger, who was then a promising young scholar who had not yet received a professorship. He thus became one of a group of students such as Leo Strauss, Karl Lowith, and Hannah Arendt. He and Heidegger became close, and when Heidegger received a position at Marburg Heidegger followed him there. It was Heidegger's influence that gave Gadamer's thought its distinctive cast and led him away from the earlier neo-Kantian influences of Natorp and Hartmann.
Gadamer habilitated in 1929 and spent most the early 1930s lecturing in Marburg. Unlike Heidegger, Gadamer was strongly anti-Nazi, although he was not politically active during the Third Reich. However the war years were tumultuous ones, and Gadamer quietly took advantage of the turmoil and the obscure, apolitical nature of his scholarship to gain several promotions. By 1945 he was Dean of Philology and History Department and chair of the Philosophy Department of Leipzig. In 1946 he was found to be untainted by Nazism by the American occupation forces and named rector of the university. Communist East Germany was little more to Gadamer's liking than the Third Reich, and he left for West Germany, accepting Karl Jaspers's invitation to a chair of philosophy in Heidelberg in 1949. He remained in this position until his death in 2002.
It was during this time that he completed in magnum opus Truth and Method (in 1960) and engaged in his famous debate with Jürgen Habermas over the possibility of transcending history and culture in order to find a truly objective position from which to criticize society. The debate was inconclusive, but marked the beginning of warm relations between the two men. It was Gadamer who secured Habermas's first professorship in Heidelberg. Another attempt to engage Jacques Derrida proved less enlightening because the two thinkers had so little in common that it proved impossible to find common ground.
Gadamer's philosophical project, as explained in Truth and Method, was to elaborate on the concept of "philosophical hermeneutics" which Heidegger initiated but never dwelt with at length. Gadamer's goal was to uncover the nature of human understanding. In the book Gadamer argued that 'truth' and 'method' were at odds with one another. He was critical of two approaches to the human sciences (Geisteswissenschaften). On the one hand, he was critical of modern approaches to humanities that modeled themselves on the natural sciences (and thus on rigorous scientific methods). On the other hand, he took issue with the tradtitional approach to the humanities, stemming from Wilhelm Dilthey, which believed that correctly interpreting a text meant recovering the original intention of the author who wrote it. In contrast to both of these positions, Gadamer argued that people have a 'consciousness affected by history' and that they are embedded in the particular history and culture that shaped them. Thus interpreting a text involves a 'fusion of horizons' in which the scholar finds the ways in which the text's history articulates with their own background. Truth and Method is not meant to be a programmatic statement about a new 'hermeneutic' method of interpreting texts. Gadamer intended Truth and Method to be a description of what we always do when we interpret things (even if we do not know it).