Lightness and Brightness and Other Confusions

etween primary and secondary sensory qualities. According to Galilei – and
later to John Locke (Locke 1975, pp 135–141) – primary characteristics, such
as hardness, mass and extension in space and time are properties of objects,
whereas secondary characteristics, such as colour, texture and shape, are
produced by the mind. Galilei thought that “colours – – are no more than
mere names so far as the object in which we locate them are concerned, and
that they reside in consciousness. Without a living creature experiencing
them, they would not be there.” (Galilei 1957, p 274).
RENÉ DESCARTES 15 points out that our senses often deceive us and that this is
the reason why they cannot give us full certainty. His doubt principally concerns
the ability of the senses as such to give us any knowledge about the
world at all; he considers all perceptions of the outer world as deceptive appearances.
(Descartes 1953, p 95). What we perceive is, however, not guided
by our will, it comes to us involuntarily. According to Descartes, this indicates
an existence of something outside of his mind, and thus, an external world.
(Descartes 1953, p 134). The ultimate solution to the problem of the connection
between an outer material world (res extensa) and an inner conscious
world (res cogitans) is done referring to a good and omniscient God, who
cannot provide human beings with conceptions of the world as mere illusions.
(Descartes 1953, 137–138). Descartes claims – as Locke does – that physical
objects themselves have no colour, only a power or disposition to arouse in
the viewer the idea that objects have special colours. But both of them regard
this “illusion” as natural, unproblematic and, in practice, possible to ignore:
to the naïve – not philosophically reflecting – everyday perceivers the objects
have their special colours; it is the nature of perception. A sophisticated perceiver,
however, knows that colour is the power to make us experience the
objects as coloured. (Maund 1995, pp 7–8).
Knowledge beside the world
IMMANUEL KANT 16 takes his starting point from human consciousness and the
human world of experience. By introspection he tries to describe the principles
of our conception of the world and ignore the outer reality, the world as
independent of how we perceive it. His thesis is that beyond our senses we
have no access to the outer world and that knowledge about the world is dependent
on a priori given abilities. (Kant 2004, p 111–112). Experiences of
space and time are, a priori, given and perceptual and not conceptual. (Kant
2004, pp 113–124).
We approach the manifoldness of the external world with what he calls transcendental
consciousness; by representation of space and time and by a num-
15
French philosopher, 1596–1650
16
German philosopher, 1724–1804
19