X is true if, and only if, p. [...] we shall call a definition of truth “adequate” if all these equivalences follow from it. [...] The definition of truth which was outlined above [...] implies all equivalences of the form (T). In this connnection it is important to notice that the conditions for the material adequacy of the definition determine uniquely the extension of the term “true.” Therefore, every definition of truth which is materially adequate would necessarily be equivalent to that actually constructed. The semantic conception of truth gives us, so to speak, no possibility of choice between variaous non-equivalent definitions of this notion..