Q: Recent weather stories have referred to catastrophic floods that “will only become more common” and heat waves “expected to only intensify in the years ahead.” What is “only” doing in those sentences?
A: Here “only” is an adverb meaning “inevitably,” and it’s often used in forecasting something bad. Those two examples are dismal forecasts, contrary to what one would wish, and at the same time seen as certainties.
Standard dictionaries define this use of the adverb in varying ways, but all imply both the certainty of the result and its contrary or negative nature. In fact, some split their definitions of “only” to separate the two notions.
For instance, The American Heritage Dictionary of the English Language says “only” here can have these meanings: “a. in the last analysis or final outcome; inevitably,” as in “actions that will only make things worse”; and “b. with the negative or unfortunate result,” as in “received a raise only to be laid off.”
And Merriam-Webster has these meanings: (1) “in the final outcome,” as in “will only make you sick”; or (2) “with nevertheless the final result,” as in “won the battles, only to lose the wars.”
The adverb is often used with verbs that are either modals (like “will,” “would,” “can, “could,” etc.) or are in the infinitive. Your examples illustrate each usage: “will only become more common” and “expected to only intensify.”
The Oxford English Dictionary, an etymological dictionary based on historical usage, discusses these adverbial uses of “only” among those that emphasize “the contrary nature of a consequence.”
In one such use, Oxford says, the adverb is “frequently” used with a modal verb or infinitive to mean “inevitably although contrary to intention or desire.”
The dictionary’s earliest example is from a 17th-century sermon and shows “only” followed by an infinitive: “serving only to make a servant more disposed & more able too, as well for the plotting as the acting of villany” (from a collection, King Davids Vow for Reformation, by the Anglican clergyman George Hakewill, 1621).
And the OED’s next citation, from later in the century, has “only” plus a modal verb: “This unlimited power of doing anything with impunity, will only beget a confidence in kings of doing what they list” (from Justice Vindicated, by Roger Coke, 1660). Here the archaic verb “list” means wish, desire, or choose.
The dictionary’s most recent example, from a show-biz memoir, is in a description of Robert Redford: “He is very into incognito so he sports lots of scarves and mufflers and hats and shades, which only make him look more Redfordish” (You’ll Never Eat Lunch in This Town Again, 1991, by Julia Phillips). In that sentence, “look” is an infinitive.
The other use of “only” that emphasizes “the contrary nature of a consequence” also originated in the early 17th century, according to the OED.
In this case, the adverb is “followed by a dependent infinitive clause” and means “with no other consequence or result than.” And that consequence is sometimes unexpected, surprising, or ironic.
This is the OED’s earliest citation: “He recouerd [recovered] … only to be made more miserable” (from The Countesse of Mountgomeries Urania, a prose romance by Lady Mary Wroth, 1621).
We still use the adverb in that same way. This is the OED’s most recent example: “Cursing Rachel and Jeff for having stolen me away from the detention centre … only to bring me to this dungeon” (from By the Sea, a novel by Abdulrazak Gurnah, 2001).