 But there is another interpretation, marked by  intonation[23]  and other features, on which the negation in (9) denies the “not all” implicature of “The boy ate some of the cookies”, and is thus consistent. The question is how to account for the two different interpretations of negations given that the word “not” seems unambiguous (Geurts 1998). Horn (1989: 362–4; 370–5) and Burton-Roberts (1989) propose that the marked interpretation of (9) is an implicature. W. Davis (2016a: Ch. 6) argues that it is an idiom that plausibly evolved from a generalized conversational implicature.