The words you choose and the register (formal, informal, technical, colloquial) you maintain directly affect how readers perceive your credibility and the argument's accessibility and persuasive impact. Diction signals not just literal meaning but also your relationship to audience and subject matter. Register consistency helps readers know what to expect; strategic register-shifting can signal irony, increase intimacy, or emphasize a point. Mastering diction and register means aligning word choice with argument purpose and audience expectations.
Take a persuasive passage and rewrite it in three different registers: highly formal, conversational, and technical. Notice how the argument feels different in each version. Identify passages in published arguments where register-shifting serves a rhetorical purpose.
Formal register is not always more persuasive; register choice should match audience and purpose. Inconsistent register within a piece confuses rather than persuades.
Every word you choose in an argument does double duty: it conveys a proposition and it signals something about *you*. That second function is what diction and register control. You already know that word choice shapes effect — that "passed away" feels gentler than "died," that "utilize" sounds more bureaucratic than "use." In argumentative writing, these effects aren't decorative; they shape how readers assess your credibility, judge your relationship to the subject, and decide whether the argument is for them. Diction and register are the levers that control this calibration.
Register refers to the overall pitch or level of formality your language sustains: formal (elevated vocabulary, complex syntax, impersonal address), conversational (contractions, direct address, simpler sentence structures), or technical (domain-specific terminology, assumed shared expertise). None of these is inherently better. A legal brief demands formal register because its readers expect it and because departing from it signals lack of professional seriousness. An op-ed for a general audience in a conversational register signals accessibility and trust — the same content in formal register might alienate readers by making them feel condescended to or excluded. The key is that register is a choice about audience relationship, not a proxy for quality.
Diction operates within whatever register you choose: it refers to the specific words selected and their texture — denotation, connotation, precision, length, origin (Latinate vs. Anglo-Saxon). Even within formal register, choosing "commence" over "begin" or "terminated" over "ended" creates slightly different effects. Writers who control diction consciously can do nuanced work: a single colloquial word dropped into formal prose can signal irony or intimacy; a sudden rise in precision mid-paragraph can mark the moment an argument gets serious. These are strategic register shifts — deliberate departures from the prevailing register for local effect.
The failure mode most writers fall into is inconsistent register without purpose. Mixing formal and informal language signals not sophistication but carelessness — the reader cannot tell whether the tonal lurches are intentional. Before you can use register-shifting strategically, you need to establish a dominant register clearly enough that departures from it read as deliberate. Think of it like musical key: you can only make a dissonant note *expressive* if the listener has internalized the tonic. The practical skill is first auditing your drafts for unintended register inconsistencies, then asking of any that remain: is this shift earning something — irony, emphasis, intimacy — or is it just noise?