In Tristram Shandy, Sterne refers to Locke's essay:

Pray, Sir, in all the reading which you have ever read, did you ever read such a book as Locke’s Essay upon the Human Understanding? ——Don’t answer me rashly, –because many, I know, quote the book, who have not read it,—and many have read it who understand it not.

The quote reveals Sterne's opinion that even many educated people have no understanding of Locke's philosophy and do not conduct their lives as rationally as Locke might believe and wish.

To many critics, Tristram Shandy is a comic response to the two theories of association that Locke describes in his Essay. First, Locke explains that human thought progresses in a logical fashion as humans take simpler ideas and bring them together through association to create more complex thoughts. Second, however, Locke states in his essay that humans can connect thoughts randomly as well as in an orderly and logical way--but dismisses this way of thought as too chaotic.

To Sterne, however, as he illustrates in Tristram Shandy, humans are much more likely to make random associations between ideas than logical ones. What drives human understanding, he argues, is not primarily logic but what he calls our "hobby horses" or obsessions. For example, because Uncle Toby is obsessed with warfare, when Tristram's father uses the word "siege" as metaphor to describe a philosophic idea—philosophy being his own obsession—Uncle Toby associates the word with literal sieges in warfare and understands what his brother says in that context.

Tristram Shandy, with its many digressions and misunderstandings which are driven by people's peculiar interests and preoccupations, gently explores and pokes fun at Locke's picture of a rational universe of association. While Locke dismissed his second idea of random association as too illogical, Sterne believes that this is, in fact, how most of human life operates. Thus we tend to go in circles and not get very far in our thinking.