Sense data

The theory of sense data is a view in the philosophy of perception, popularly held in the early 20th century by philosophers such as Bertrand Russell, C. D. Broad, H. H. Price, A. J. Ayer, and G. E. Moore. Sense data are taken to be mind-dependent objects whose existence and properties are known directly to us in perception. These objects are unanalyzed experiences inside the mind, which appear to subsequent more advanced mental operations exactly as they are. Sense data are often placed in a time and/or causality series, such that they occur after the potential unreliability of our perceptual systems yet before the possibility of error during higher-level conceptual analysis and are thus incorrigible. They are thus distinct from the 'real' objects in the world outside the mind, about whose existence and properties we often can be mistaken. Talk of sense-data has since been largely replaced by talk of the closely related qualia. The formulation the given is also closely related. None of these terms has a single coherent and widely agreed-upon definition, so their exact relationships are unclear. One of the greatest troubling aspects to 20th century theories of sense data is its unclear rubric nature. Bertrand Russell heard the sound of his knuckles rapping his writing table, felt the table's hardness and saw its apparent colour (which he knew 'really' to be the brown of wood) change significantly under shifting lighting conditions. H. H. Price found that although he was able to doubt the presence of a tomato before him, he was unable to doubt the existence of his red, round and 'somewhat bulgy' sense-datum and his consciousness of this sense-datum. When we twist a coin it 'appears' to us as elliptical. This elliptical 'appearance' cannot be identical with the coin (for the coin is perfectly round), and is therefore a sense datum, which somehow represents the round coin to us. Consider a reflection which appears to us in a mirror.