The nature, the importance, and even the existence of mental images is a subject of dispute amongst psychologists and philosophers. On the one hand it seems evident that normal people enjoy a moderately rich inner life, in which remembered scenes, tunes, tastes, and smells can be conjured up and new versions created and relished; the state of mind once this is done is somehow like but also quite unlike the state of seeing, hearing, and tasting original things. Images are typically ‘faint’ or ‘blurry’, but merely imagining a tiger does not differ from seeing a tiger only in its faintness or blurriness, or it would resemble seeing a tiger in a fog or poor light, which it does not. Furthermore an imagined tiger, unlike any actual tiger, need not have a definite number of stripes or claws. It is not therefore simply an ‘inner picture’ of a tiger, and visual images are unlike pictures in other ways as well: for instance they cannot withstand scrutiny, and there is a limit to the manipulations one can make while retaining them. The view that images play a fundamental role in thinking was attacked by Wittgenstein, one of whose arguments was that if they are thought of as inner presences that explain, for instance, capacities for recognition and classification, then we must ask how they themselves are recognized and classified. The shadowy nature of images has led some philosophers to think of them as a useless adjunct to underlying cognitive processes of representation, not themselves part of the machinery. But it is likely that evolution will favour an animal with the capacity to generate an ‘off-line’ simulation of experiencing various situations, perhaps in order to rehearse successful strategies. Hostility to images also makes it difficult to account for their central role in the creative lives especially of primarily non-linguistic thinkers, such as artists and musicians. See also idea.