People often use the verb “to impact” instead of “to affect” or the noun “impact” instead of “effect” because they can’t be bothered to remember the difference between affect and effect.
One self-styled writer tweets, “Yep, now those words [affect, effect] are being replaced in the lexicon with things that aren’t confusing (re: impact). Language evolution wins!”
Nope. There are few contexts in which “affect” and “effect”, used properly, might be confusing to the reader. If a writer can’t use “affect” and “effect” properly without unintentionally confusing readers, she shouldn’t be in the writing business.
There are occasions on which “impact” might be a better word choice than the noun “effect.” An impact is a strike or blow; while an effect might be gradual, an impact is sudden. While an effect might be subtle, an impact is blatant. If one thing has a sudden and noticeable effect on another, it has (or, preferably, makes) an impact.
By the same token, sometimes “to impact” might conceivably be a better word choice than the verb “to affect.” I’m a big fan of pressing words into unusual metaphorical duty. “To impact” (itself a neologism) also suggests violent contact (smack!), and might serve in place of “to affect” when one thing smacks metaphorically into another.
The Law of Requisite Variety dictates that a writer will write better if she knows more nuantially different ways to say “effect.”
All of this is by way of introduction to the stupid neologism of the day: impactful. As in, “Impactful Opening Statements” (link is to PDF of 2009 TCDLA Rusty Duncan Advanced Criminal Law Course agenda).
Why not “Effective Opening Statements”? (I favor “Affective Opening Statements.”) You might want your opening statement to make an impact on the jury — to strike them, to make an impression on them — rather than have an effect on them. Fair enough, I’ll grudgingly spot you the first two syllables. But if you’ve got to create a synonym for “effective”, why “impactful”?
Your opening statement isn’t really full of impact; you hope for it to make (or have) an impact on the jury. There are more and nearer analogues for impactive (active, effective, discursive) than impactful (harmful and dreadful come to mind). Impactive is a much less ugly word, avoiding the gear-grinding -ctf- sound of impactful.
Finally, impactive has linguistic legs. If you use impactive you’re following in the penstrokes of F. Scott Fitzgerald (in 1934) and William Faulkner (in 1942); if you use impactful you sound like one of the yahoos in marketing.