Cognitive theories of metaphor rest on two main assumptions: (1) Metaphor is a conceptual structure that is simply expressed by linguistic forms. (2) The conceptual interaction promoted by metaphors has a general formula: A (the target) is B (the source); e.g., 'Life is a journey'. Both assumptions, which hold for consistent metaphors, are challenged by inconsistent ones. On the one hand, an inconsistent complex concept is not simply expressed, but constructed by a linguistic form. On the other hand, the formal frame of conceptual interaction is a variable structure, whose form depends on the grammatical and functional properties of the metaphorical focus. Adapted from the source document. (LLBA 2000, vol. 34, n. 2)