Definition of Characteristic
Definition Last Updated 17-Dec-2015 12:51
A characteristic is something that can be said about1Formally, predicated of the content of a particular region – somewhere with defined extent in space – at a particular time. Characteristics are divided into observables, which are intrinsic, and tags which are extrinsic. The noun characteristic is a generalisation, and does not necessarily imply is characteristic of, in the sense of being a distinguishing feature.
The value of a characteristic, quantitative or qualitative, is determined under particular conditions (i.e. of time, place, , etc.) by:
- Observation, or
- Inference, i.e. calculation or reasoning from the values of one or more other attributes, which may also be considered as the application of standard rules of mathematics and logic, such as Area of Circle = πr2
Article Last Updated 17-Dec-2015 12:51
We may also look at the light received from that region and say that the region has particular colour; in general, colour is a tag and not an observable (unless carefully defined so as to make it one) because colour is a label expressing a perception whose nature depends on the circumstances of the observation2Is colour determined in the absence of external illumination? Or, if external illumination is present is the colour considered to be the colour of the emitted light, the reflected light or some combination of the two, when we know full well that changing the colour of the illuminating light may affect our perception? and by what or whom the observation is made.
Someone of normal vision might say the light is grey; someone colour-blind might say that it is pink. The spectrum of light received from the region, described in terms of the measured intensity of light at particular wavelengths, would be an observable. If colour were defined in terms of, say, the average peak frequency of light received, it would be an observable rather than a tag.
The distinction between observables and tags is rarely of fundamental importance, but tags do play a key role in defining relationships.
Notes [ + ]
|1.||⬆||Formally, predicated of|
|2.||⬆||Is colour determined in the absence of external illumination? Or, if external illumination is present is the colour considered to be the colour of the emitted light, the reflected light or some combination of the two, when we know full well that changing the colour of the illuminating light may affect our perception?|