Lakoff, George. 1986. The meanings of literal. Journal Article. pp. 291-296
Abstract
Lakoff defines four uses of 'literal': conventional literality, subject matter literality, non-metaphorical literality, and truth-conditional literality and then goes on to say: "Johnson and I discovered that the assumptions [of a monosemous use of 'literal'] are false. But it is difficult to discuss our findings using the word 'literal' in its ordinary sense, because that very use of the word presupposes the opposite of what we discovered. It would be useful if we had four separate English words for each of these four senses of literal. But we have only one word. All we can do in such a situation is point out the problem, be careful to distinguish these four senses, and suggest a possible use of literal as a technical term. I suggest here that literal, in any technical discussion, be restricted to the meaning of Literal 3 [non-metaphorical literality], the sense of being directly meaningful, without the intervention of any mechanism of indirect understanding such as metaphor or metonymy. But because of possible confusions, it is good policy to avoid the word 'literal' as much as possible in discussions of metaphor".(George Lakoff)