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The category of relation, Aristotle thought, has a degree of being. With the discovery of the logic of relations in the nineteenth century, it occupied a central position in the theory of knowledge. Ernst Cassirer was developing a theory of perception based on group theory, according to which the perceived objects are the invariants underlying sets of transformations between perceived aspects.Cassirer´´s theory of perception appeals that perceptual knowledge can be detached from knowledge of the entities forming the form or the structure,it is not tied down or referred to any particular realm of content. Cassirer pointed to that the sensationalist theories used to describe perception as a mosaic of simple sense data a mere aggregate or bundle of isolated impressions.Modern Gestalt psychology has corrected this view showing that perceptual process imply fundamental structural elements.My main theme of the present book is to show that the major argument of the systematic structure implied by the few theoretical statements of group theory is sufficient to account for a large number of perceptual organization as emphasized by the Gestaltists.

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Mohamed Sayed Hassan has BA in Philosophy from Ain Shams University, Cairo, and MA in History and Philosophy of Science from Leeds University, Uk and PhD from Durham University,Uk. He is Presently a lecturer at Ain Shams University, Egypt. His research interests include Philosophy and History of Science and Philosophy of Perception.

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