The British philosopher Bertrand Russell wrote:
«We may now take a survey of the sources of our knowledge, as they have appeared in the course of our analysis. We have first to distinguished knowledge of things and knowledge of truths. In each there are two kinds, one immediate and one derivative. Our immediate knowledge of things, wich we call acquaintance, consists of two sorts, according as the things known are particulars or universals. Among particulars, we have acquaintance with sensa-data and (probably) with ourselves. Among universals, there seems to be no principle by which we can decide which can be known by acquaintance, but it is clear that among those that can be so known are sensible qualities, relations of space and time, similarity, and certain abstract logical universals. Our derivative knowledge of things, which we call knowledge by description, always involves both acquaintance with something and knowledge of truths. Our immediate knowledge of truths may be called intuitive knowledge, and the truths so known may be called self-evident truths.» (Bertrand Russell, The problems of philosophy, pages 62-63, Oxford University Press, 2001; the bold is put by me).
On distinguishing knowledge of things and knowledge of truths Russell commits a logical error: things are truths, are a part of the truth. To see and touch a tree or an apple is to know things, and simultaneously, it is to know truths. Russell separates truth from empirical perception, from sensa-data and that is an error: empirical data contain, to a greater or lesser degree, truth. The red colour of strawberries i see and its sweet taste brings me partially the truth of these strawberries.
Another error of Russell is to considere particular the knowledge by acquaintace, based on sensa data. In fact, the knowledge obtained by sensa-data is simultaneously particular and universal. If it were not so, the drivers would always bump against each other on the roads because the sense-data would not show the same road to those who are, at the same moment, in the same three hundred meters of public road in their cars, in progress. But there is a commmon perception of the road and of the positions of all cars in different minds of drivers, in a given moment, and that proves that sensa-data have universitality and not only particularity.
© (Direitos de autor para Francisco Limpo de Faria Queiroz)
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