A distinction needs to be made between two types of case in which something (a sign, an expression) is described as an image: one in which what is in question is the function, the role, the use of this sign or expression ("this story, this drawing, are a good image of the pain experienced by this man"), the other in which it is the form, the "nature" of the sign that is of interest. This is obvious, it seems to us, when we consider object-images, for example. "It's useful here to introduce the concept of image-object. The figure, for example, would be an "image-face". I relate to it in more ways than one, just as I would to a human face. I can study its expression, react to it as I would to a human face. A child can talk to man-images, or animal-images, he can treat them as he treats dolls" (PU II, p. 194). The expression "to be an image" can thus mean either "to have the function of an image, to be a description", or "to have the form, the functioning of an image."
In the Tractatus, Wittgenstein makes no distinction between the nature and function of a symbol. On the contrary, the confusion is explicit and assumed, since to say of something that it is an image, a proposition, is to say at once something about its nature and its function - its form and its use. It is the nature of images and propositions that is described by the relation of reproduction(Abbildung): there is a common logical structure between the fact and the image or proposition that reproduces it. It is, on the other hand, the function of images and propositions that is concerned by their characterization as figurations. We're interested in the inseparable nature of the relations between reproduction and figuration in the Tractatus (which we'll be clarifying primarily from paragraph 4.016 onwards), and in the way it was called into question in the '30s. In particular, we'll be looking at how the primacy given to questions of use in this period tends to make Wittgenstein reject considerations of form, which nevertheless remain present, but in a way that seems parasitic. We will then try to understand to what extent Wittgenstein's later texts shed (or fail to shed) a more satisfactory light on the ambivalence (form/use) of the concepts of proposition and image, and enable us (or not) to get rid of the philosophical cramps caused by it.
