When writing about instinct, is the adjective instinctive or instinctual? Are they synonymous, or have they differentiated? Are we just to rely on our editorial instincts to choose?
Many usage mavens, including Bryan Garner and Charles Harrington Elster, consider instinctual a needless variant and encourage writers to stick with instinctive. And they might have a good argument. Instinctive has been around a lot longer — since the 15th century.
Instinctual only dates back to the mid-1920s. It may have been too new a word to have been noticed by H.W. Fowler before he published the first edition of A Dictionary of Modern English Usage in 1926. It’s probably a safe bet that he would have panned instinctual as a pointless neologism, though; he used only instinctive throughout the text. Regardless, the recommendation to avoid instinctual found its way into Ernest Gower’s 1965 second edition of the book.
So the short answer, when you’re faced with choosing between instinctive and instinctual, is to use instinctive. You’ve got the authorities on your side, and no one can argue against you.
But where does that leave instinctual? Should it be abandoned, destined centuries hence to be the subject of blogs about quaint language idiosyncrasies? Or is there a place for instinctual in our vocabulary?
Modern lexicographers recognize that both words are used with some frequency and therefore, being descriptivists, include both spellings in their dictionaries. American Heritage (online at least) treats the words as essentially synonymous: Both definitions listed for instinctual are encompassed, word for word, in the definitions for instinctive, though the latter word gets some expanded commentary and more examples.
Merriam-Webster, in my opinion, makes the matter more confusing than it should be. If you look up instinct, you will find as run-on entries instinctual and instinctually, but not instinctive. If you stop there, it’s understandable that you would think instinctual is the adjective of choice. But if you look a bit farther down the page, or in the online dictionary (and this is the confusing part) on a completely different web page, you’ll find instinctive listed as its own headword.
Luckily, the M-W editors have tackled the instinctive/instinctual question online. After examining usage data, they found that the two alternatives may have become differentiated in some specific fields of science:
Instinctual does tend to appear in writings pertaining to the science of evolutionary instinct. A person writing from a scientific background might be more liable than a layperson to see a distinction in use between instinctive and instinctual, and more critically, might be inclined to see a need for such distinction
The distinction they find has instinctive used to describe acts done by instinct, and instinctual used to mean “relating to instinct.” For example, a skunk’s spraying when cornered is instinctive, but its desire for solitude may be instinctual.
Though the comparisons aren’t perfect, in this way of thinking, instinctive is like musical or volcanic to instinctual‘s musicological or volcanological.
So if you’re editing for the general public, instinctive is probably the best bet. But if you’re editing scientific manuscripts, some consideration may be in order.
I know some of our readers are science editors, and we would certainly love to hear their experiences with these words. Are they denoted in a journal’s convention sheet? Do authors request specific usages? Log on and let us know in the comments.