Faced with a set of needs of different intensities and which he perceives more or less indistinctly, a consumer is not normally capable of selecting among the elements belonging to his set of possible consumptions, those he prefers or is indifferent to and those from which he is likely to derive utility. Moreover the goods and services are attainable to different degrees (available in supply space) and his knowledge is perfect only in border-line cases with the result that his world is generally imprecise. Even someone with an exceptional gift for discrimination is not capable of formulating for any pair of goods, his preference or indifference according to binary logic. The purpose of this paper is to remove the usual assumption (which it must be added is essential to the classical theory of consumer behaviour) that the consumer is capable of discriminating perfectly between different goods. It is well known that his behaviour, like any human behaviour,is by nature imprecise. Furthermore, unlike the usual theory, the goods capable of satisfying needs are assumed to be scattered in a supply space and transportable.The agent is located at a given point of demand. (...)