You take a peek out the window. It looks pleasant and calm. Fluffy white clouds shade the sun, birds are chirping and the trees are gently swaying in the breeze. You decide to head out for a walk. After a pleasant half hour out in the mild weather, you notice the wind pick up and dark angry clouds beginning to gather. The birds have stopped their chirping and you realise the walk back may not be so pleasant. You turn back quickly and pick up your pace.

It’s too late. The clouds soon unleash their anger, drenching you in the process.

As you get home, dripping wet, shivering and feeling miserable, you might think to yourself, “If I hadn’t gone for a walk, I wouldn’t have been drenched.”

That thought is a counterfactual. It’s essentially made up of two counterfacts: 1) You didn’t go for a walk; and 2) You weren’t drenched. Independent counterfacts are almost never interesting on their own. You would never say to someone “I might not have gone for a walk.” without adding some context. By contrast, you might indeed say “I went for a walk.” without adding anything extra.

We link two or more counterfacts together into a conditional because it is useful so long as the conditional is factual. (Or, being a bit more careful with words, so long as the conditional has a sufficient chance of being true.) “If I hadn’t gone for a walk, I wouldn’t have been drenched.” is very likely true, and hence potentially useful. This applies to any conditional, whether or not it’s made up of facts or counterfacts or some mixture of the two. For example, “If I had gone for a walk, I would have been drenched.” is also very likely true and useful — because (in fact) you did and you were.

Counterfactuals in everyday life tend to be applied to individual situations that have already happened. It’s appropriate that they use the past tense — “If I had gone…” rather than ‘If I go…”. But counterfactuals are useful because of what they teach us for the future. You got drenched that time, but with your new knowledge, you may be able to avoid getting drenched next time. You just need to follow the counterfactual path, either always (a bit drastic in this case) or conditionally (like after checking the forecast).

Thinking about one single case in the past is the simplest way to develop a useful counterfactual, but it’s certainly not the only way. Indeed, this post has plenty of examples of other ways.