Persuasive writing often takes the form of an argumentative essay: you first construct a thesis, then justify it with compelling evidence. As the writer you assume a tone--an attitude toward your subject and audience--that persuades the reader you are a credible essayist. Generally such a tone is purposeful and assertive, detached rather than impassioned. There are however exceptions to this rule of thumb, most notably in the passion of Elizabeth Cady Stanton and the satire-cloaked anger of Jonathan Swift.

A Purposeful and Fair-minded Tone

The tone of most persuasive essays is sensibly factual, without undue emotion; many curricular essay assignments recommend that tone be purposeful--"serious and fair-minded," according to Michael Fleming--as opposed to overtly fiery or pleading. An essay's success depends on the reader's agreement to listen to your argument before acceding to or disagreeing with it; a begging or sarcastic tone will quickly dissolve the reader/writer agreement. Channel your desire to convince the reader into a tone that conveys your conviction. If you have confidence in your own argument, a compelling tone should come naturally to you.

An Emotionally Charged Tone

This is not to say that emotion has no place in persuasive writing; with the right audience and a discerning essayist, remarkable results can be achieved with a fervent tone. Elizabeth Cady Stanton, one of the pioneers of the women's rights movement, passionately pleaded for women's education in her 1892 piece "Solitude of Self." She compares obstacles to women's education to "putting out the eyes; to deny [our] rights ... is like cutting off the hands." These vivid similes arise from her conviction about the justice of educational equity; her tone is appropriately emotional.

Swift's Unique Persuasion

An essayist who deliberately adopted a complacent tone for his authorial persona was Jonathan Swift in 1729's "A Modest Proposal." Swift, furious over the treatment of the impoverished Irish, suppressed his anger in favor of a coldly detached tone; he described, in the voice of a heartless economist, the profit to be had from selling poor Irish babies for food: Each infant a "reasonable dish ... very good boiled on the Fourth day." Swift creates persuasive satire out of his anger over a serious social problem.

The Best Balance

If you study persuasive pieces--Martin Luther King Jr.'s race-relations plea "Letter From Birmingham Jail" (1963) or Judy Brady's feminist satire "I Want a Wife" (1971)--you will naturally find passion for the subject, tempered with good sense, restraint and the willingness to see both sides. The ability, in your persuasive essay's tone, to balance between both factual and emotional sensibilities will create your successful persuasive voice.