a) in mathematic, by the restriction that a class cannot be a member of itself nor can one of the members be the class.
b) in logic, by the solution to the classic logical paradox, ‘This statement is false.’ (If the statement is true, it is false, and if it is false, then it is true, and so on.) The actual truth value of the statement is of a different logical type than the statement itself.
c) in behavior, by the fact that the reinforcement rules for exploration in animals is of a completely different nature than those for the process of testing that occurs in the act of exploration.” (1983: 24).
“The informational effects between levels and types is called feedback and is probably the major distinguishing feature of cybernetic systems.” (1983: 39)
“Differences of the same or different logical type interacting at different levels (hierarchical or logical respectively) will result in the modulation of the difference on the lower level.” (1983: 49)
Gregory Bateson:
A Logical Type: 1) The name is not the thing named but is of different logical type, higher than the thing named. 2) The class is of different logical type, higher than that of its members. (Mary Catherine Bateson, 1987, pp. 209-210).