Deleuze distinguishes between propositions of science, logic and opinion (modalities of judgement). Last night I read these paragraphs and couldn't make head or tail out of them:
... what opinion proposes is a particular relationship between and external perception as state of a subject and an internal affection as passage from one state to another (exo- and endoreference). We pick out a quality supposedly common to several objects that we perceive and an affection supposedly common to several subjects who experience it and who, along with us, grasp this quality.
...it is a function or a proposition whose arguments are perceptions and affections.
He gives an examples of cat or dog lovers that form a group ( or a tribe, as we'd say today):
...we grasp a perceptual quality common to cats or dogs and a certain feeling that makes us like or hate one or the other: for a group of objects we can extract many diverse qualities and and form many groups of quite different, attractive or repulsive, subjects (the "society" of those who like cats or detest them), so that opinions are essentially the object of a struggle or an exchange.
The last phrase stuck me as particularly important, but I still couldn't understand his reasoning. So I watched some Vonnegut videos and went to bed slightly frustrated with my own thickness. Then in the middle of the night I woke up with an idea of how to think about it.
Let's say, there's an external object - a kitten. I have positive feelings about the kitten because it is extraordinary fluffy and I extend this feeling to all other cats and kittens. Now, I use the feeling to divide everybody into those who share my feelings and those who do not. I accomplish that, by sharing my feelings with people ("the society") and observing their reactions. We form a sharing community and fight or ignore those who don't share our feelings.
Needless to say that the web was originally created for sharing propositions of science and logic, but it became a medium for sharing opinions (e.g. stars on amazon and likes on facebook) and forming loving/fighting tribes.