what principle does trillin use to divide and identify the four types of eaters? "The extendable fork"

The Motifs of trilling on the four types of eaters is to illustrate and observe the foibles and quirks of the American culture. Therefore, it is because of these that Trillin uses most of his expertise in different divisions and classifications.

The confession of Trillin regarding the four types of people who eat from other people's plates undermines the categorization, this is because in real sense they are not different from other people but have different motives of engaging the behavior rule.