• Posted: October 2012
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Logical level: The levels in a hierarchy generated by logical inclusion, in the hierarchy. In the hierarchy above kayaks, yachts, ocean liners are said to be on the same level based on the premise they are the set members that fall within the set of boats (level above) that adhere to the overall set membership rule of floating.

Logical type:
Two sets are of the same logical type where there is isomorphic mapping between the sets that preserve the essential characteristics of each set. Meaning the relationship in set A is preserved among their counterparts in
set B.

Bateson In Structure of Magic (Bandler and Grinder 1975) presents the example of the mappings of visual, auditory and kinesthetic as being of different logical types. This means neurophysical representation of visual has no direct counterpart in kinesethic

The example for logical types in Whispering is the saying ‘you are comparing apples and oranges’

Usually the meaning of this saying is apples and oranges are of a different logical type e.g. there is no isomorphic mapping in the counterparts in different sets (apples and oranges)

This is certainly true if the classifier wants the fruit to make an apple pie. The set membership rule here is apples to make an apple pie. While many different apples will suffice for the task, oranges certainly will not do the job.

If the classifier is measuring the total sales of fruit for a supermarket, apples and oranges are different set members that are of the same logical type, as are pears and bananas. The set membership rule is ripe fruit to sell to the public.

Therefore logical types are determined by the intention of the classifier that creates the mental space of categorisation.

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