Consider the picture above, and consider the phrase ‘I like you’. If the girl here is saying this to the boy, we would not necessarily interpret it to mean that she is like him. We would interpret it to mean that she has a fondness for him. By the looks of the boy in the picture, he does not seem overjoyed by the news – so perhaps he cannot say the same about her. Or maybe he does more than just like her, and accepts the meaning of the phrase to mean that she cannot reciprocate.
Whatever is going on in this picture, and whatever is actually meant by the phrase ‘I like you’, the meaning is derived from the contexts in which the phrase is uttered.
‘I like you’, certainly, expresses the sense of fondness. But perhaps the girl also likes cats? Is her liking for the boy any different?
Perhaps you have already been assuming that when she says to the boy ‘I like you’ she means that she fancies him. That the ‘liking’ is based on physical attraction – after all, she may well like cats as well, but is unlikely to want to go on a romantic date with one.
Click on picture for a video introduction to 'pragmatics' from Professor Steven Pinker