A very complicated mathematical ideology as explained in part A: But best explained and used in Part B.
A: In mathematics, a binary relation R over a set X is transitive if whenever an element a is related to an element b, and b is in turn related to an element c, then a is also related to c.
Transitivity is a key property of both partial order relations and equivalence relations.
B:I touch my balls, then I touch your forehead. By definition of Transitive Theory my balls have now touched your forehead.
-Go forth and enjoy your new found powers of Transitive Theory