Mach believes humans think in an economical manner where past experiences and knowledge are systematically reorganized to fit a pattern (Mach 211). Rather than analysing each experience in detail, humans refer to similar or related experiences as groups, which allows for the “least expenditure of thought” (Mach 197). In line with this mentality springs the concept of ‘things’ and ‘bodies’. Mach states that colours, sounds, temperatures, etc. are called sensations (Mach 208-209). When certain sensations are present repeatedly, they would fit into a pattern. To allow for future reference on this knowledge within the mind, the pattern receives a label. An example would be when a person sees an orange, bouncy, sphere object which has a mildly rough texture, the label ‘basketball’ springs to mind. The ‘basketball’ would not be a physical object; it would simply be a “mental symbol” for the sensations and Mach states that “symbols do not exist outside of thought” (Mach 201).
Russell believes that certain things, such as a table or a cat, consist of sense-data −− which are colours, sounds, smells, etc. −− and that the immediate awareness of such things is known as a sensation (Russell 12). Also, the existence of an object is not necessarily associated with the sense-data as different people receive different sense-data when they are under the belief that they are viewing the same object (Russell 20). In addition, a person would only know the certainty of perceived sense-data rather than of the object since sense-data depends on the perception and relation of the object to the perceiver (Russell 16). Russell then states that although there is no proof of a physical world, the belief that there are objects corresponding to sense-data allows for the simplification people’s experiences. Therefore, believing in an
Cited: Mach, Ernst. Popular Scientific Lectures. Chicago: The Open Court Publishing Company, 1898. Russell, Bertrand. The Problems of Philosophy. London: Oxford University Press, 1912.