Because a thesis statement sets the stage for the entire essay, it must read clearly. Thesis statements that are not parallel, however, can cause confusion. The following sentence, "If a high school education is no longer an adequate qualification for most jobs, then employment now requires education from a university" sounds confusing because it presents a high school education and employment as equivalent concepts. What the writer is really trying to compare, however, are a high school education and a university education. A reader can follow this thesis statement much more easily: "If a high school education is no longer an adequate qualification for most jobs, then a university education is now a basic requirement for employment."
Thesis statements that are not parallel sound choppy. In "Shakespeare uses imagery, symbolism and develops characters to demonstrate that Hamlet is insane," "imagery" and "symbolism," the first two items in the series, are both nouns, but "develops characters" consists of a verb and a noun and therefore is not grammatically parallel with the other items. Changing the thesis to "Shakespeare uses imagery, symbolism and character development to demonstrate that Hamlet is insane" creates a smooth list of reasons to support the thesis.
Thesis statement lists should also balance ideas of equal weight or significance. For example, the three ideas in the statement, "Hamlet's grief over the loss of his father, his shock at his mother's second marriage and his hairdo lead to his insanity" are not parallel in terms of significance. The first two concepts, Hamlet's grief and shock, are ideas similar in weight; however Hamlet's "hairdo," aside from being irrelevant, does not present a parallel idea. In another example, "Sally painted her nails and then got married," although not a thesis statement, still illustrates an absurd juxtaposition because the two ideas, painting one's nails and marrying, are not of parallel significance.
Parallel thesis statements pack a punch. John F. Kennedy, famous for making provocative parallel statements, once said "Ask not what your country can do for you, ask what you can do for your country." This sentence contains two clauses exactly parallel in form. The structure of the statement contributes to its overall meaning: the second clause in the sentence unravels the presupposition of the first, that it is standard for a person to value a country for its worth to her, rather than the other way around. Thesis statements can function the same way. Consider this thesis: "Hamlet's grief consumes him: it consumes his mind, it consumes his relationships and it consumes his sanity."