Definition of "counterfactual"

What would have happened if those great Chinese voyages [by Zheng He] had continued? It's one of those questions in counter-factual history about which it is impossible to be sure.

2014 September 15, Martin Gayford, “There's more to Ming than a vase ”, in The Daily Telegraph (Review)‎

The counterfactual 1982 of the novel plays variations on our historical record and contains clear allusions to the present.

2019 April 11, Marcel Theroux, “Machines Like Me by Ian McEwan review – intelligent mischief”, in The Guardian‎

Just as counterfactuals employ too much imagination to qualify as historical works, alternate history often labors under too great a load of artificial "facts" to take flight as fiction.

2004 September 5, Laura Miller, “Imagine”, in The New York Times‎

We can spin out complicated counterfactuals that justify the Iraq invasion, and complicated counterfactuals that make it look even worse.

2010 September 1, Ross Douthat, “Iraq in the Long Run”, in New York Times‎, retrieved 2021-07-15

The implicit counterfactual — that these members would support gun control if not for the $1,000 they received from the NRA — seems unlikely to me.

2015 December 3, Lee Drutman, “Here's the real reason we don't have gun reform”, in Vox‎

Roese also says counterfactuals can serve emotional purposes. You can think about how things could have been worse, and so feel better about yourself, and grateful for where you are.

2016 February 11, Noah Berlatsky, quoting Neal Roese, “'What if?': Why we can't get enough of counterfactual shows”, in The Guardian‎

Imagine a counterfactual in which we started relaxing restrictions at an even earlier time, just as the cases began to trend downward.

2021 May 14, Dashiell Young-Saver, “The Math of Ending the Pandemic: Exponential Growth and Decay”, in The New York Times‎