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10
Contrast and substitution
Imagine the situation where you want to play Ludo with four players. You have
four green counters for the first player, four blue counters for the second and
four yellow counters for the third. However, you have only three red counters.
Rather than give up the game, you might look for something which can be used
as a fourth counter for red. Even if you have a fifth green counter, that will not
be suitable, because it is indistinguishable from the counters being used by the
first player. But if you have a white counter, this can be used. It might not be
red, but it can be distinguished from the green, blue and yellow counters.
In this situation, a linguist would say that green, blue, yellow and red contrast
with each other. For this to be the case, it is important that all members
of each of these sets can be distinguished from all members of the other sets
which can occur on the same game-board. In the situation outlined above white
‘acts as’ a red, and does not contrast with red, even though perceptually there
is as big a difference between white and red as there is between yellow and red.
The contrast is defined by the game. In Ludo we have to be able to tell what
happens if two counters end on the same square. Does one take the other, or do
they accumulate to create a block to the progress of others? Red and white will
accumulate; red and yellow will take.
Note that we need to distinguish here between things we can tell apart physically
and things which act as different in the system we are working with. Red
and white can be told apart, but they function as ‘the same colour’ in the system
we are working with. The same principles apply in the linguistic analysis of language.
Consider, as an example, past tense marking in regular English verbs. Given
a set of bases such as /dju�p, lɑ�f, lυk, wɔ�k, b�n, bri�ð, dr�ɡ, fil/ , and a set
of past tense forms such as /dju�pt, lɑ�ft, lυkt, wɔ�kt; b�nd, bri�ðd, dr�ɡd,