Saturday, April 26, 2008

What does a representation represent?

It's common usage to talk about what something represents, as in "this sequence of numbers represents that sound." But it's clear that computational representations, at least, can't be said to represent anything, taken out of context. The same sequence of numbers, in the context of different uses, could represent a time series of stock prices, or a time series of predicted water levels in a reservoir, or ... . More radically, blocks of bits in memory are used to represent all the different things that can be represented computationally, and a given pattern of bits can represent numbers of different kinds (floating point or integer), or a group of characters, or a part of a data structure tied together with addresses, or... . In the context of a particular representational system, a block of bits can be said to represent whatever it is that it corresponds to in that system. But unless that context is assumed it is really meaningless to ascribe representational content to a block of bits. Anytime we ascribe content we are presuming context.

There's nothing unusual in this situation. Many attributes are commonly ascribed to things that really are determined in complex ways by the situations in which the things are encountered. Colors cannot be assigned to things independent of the viewer, for example, or independent of the context in which the thing is viewed (for striking demonstrations see A thing can be said to be "large" or "small" only in a comparative context, usually implicit, and so on.

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