In this paper I intend to discuss the relationship between understanding, truth, and explanation, starting from the problem of the interpretation of alien belief systems. The examination of this will lead us to present an analysis of the structure of understanding, and to defend its cognitive universality in so far as any identification of reality reproduces the structure of the process of understanding. This cognitive universality does not necessarily exclude, however, the possibility of reducing understanding to causal relations. With respect to this, I shall discuss the plausibility of the views of Quine, Searle and Davidson on the kind of relation that holds between cognitive processes and the causal relations in nature. In my opinion, Quine's position is untenable; Searle's view, if non-trivially interpreted, is at least implausible; and, finally, Davidson's anomalous monism can be construed in such a way that it is compatible with our analysis of the structure of understanding and with the thesis of its cognitive universality, in spite of Davidson's commitment to the ontological universality of causal relations.