William Empson's book Seven Types of Ambiguity: A Study of Its Effects on English Verse can be described as a book of literary criticism mainly using verbal analysis to show that reason can be applied to explore "expanding possibilities of alternate, multiple, and simultaneous meanings" of ambiguous words used by authors (eNotes, "Seven Types of Ambiguity Essay--Critical Essays: Analysis"). He divides his book into seven different categories of ambiguous meaning: (1) the parts of language used effectively in multiple ways at once; (2) different meanings that can be determined based on the author's one intended meaning; (3) the unconnected meaning that results from word usage, like what we see in puns; (4) the different meanings that when connected can reveal the "complicated state" of the author's mind; (5) what he calls "fortunate confusion," which are specifically similes that imply two conflicting meanings, showing the author was "'discovering his ideas in the act of writing'"; (6) "contradictory" and "irrelevant" meanings that require a reader to derive his/her own interpretations; and (7) statements that are so contradictory they show the author's mind was "divided" (eNotes, "Seven Types of Ambiguity Analysis: Form and Content"). Though criticized for his loose use of the term ambiguous, Empson's book has become a valuable edition to literary criticism.
In his review of Empson's Seven Types of Ambiguity, published in The Criterion in 1931, James Smith first proposed the criticism that Empson used the term ambiguous too loosely. The term ambiguous can be defined as referring to anything that has "several possible meanings or interpretations"; however, ambiguous is also used as a linguistics term to refer to any grammatical construction that has "two or more" possible meanings (Random House Dictionary). Hence, Smith found ambiguity in Empson's use of ambiguous do to the fact that anything ambiguous can have a range of two or more possible meanings, while Empson only used ambiguous to refer to multiple possible meanings. Empson responded to Smith's criticism and others like it in the preface he added to the second edition of Seven Types of Ambiguity. Empson responded by arguing he did not see things like puns as ambiguous simply because puns "say two things at once" (p. x). On the contrary, he considers saying two, and only two, things at once a "concise" way of using language rather than an ambiguous way of using language. Instead, Empson argues that ambiguity occurs wen one can puzzle over an author's meaning, seeing multiple possible alternative views, "without sheer misreading" (p. x). Empson's book has also be criticized for organization, and Empson did confess that many of his examples did overlap.
However, despite criticisms of Empson's usage of the term ambiguous and organization, Empson's book is praised as revealing meanings in poetry previously overlooked. As John Gross, a book reviewer for The New York Times phrased it, Empson "had the gift of being able to show you qualities in a work you would never have seen without him, and the even more important gift of enlarging your imagination, encouraging you to go on looking for yourself" (Poetry Foundation, "William Empson: 1906-1984"). Robert M. Adams, a second book reviewer for The New York Times, argued that many of Empson's interpretations "have attained classic status" ("William Empson").