Regret. Even reading the word sets the jaw to clenching. Regret. It has such menace; a heavy thud inside the mind.

The pervasive pop culture idea that we should all embrace some sort of ‘Carpe Diem’ outlook because we could all be dead tomorrow is not constructive. Not just because wet-look leggings are universally hideous on everyone.

Of course we should try to be prudent, to make rational, informed decisions and plan for the future. Delayed gratification is part of responsible adulthood.

Living each day as though it's your last with Edith Piaf warbling "Je ne regrette rien" in the back of your mind is a pretty objectively terrible way to go about your life. However, so too is making decisions and undertaking actions because you – or someone else – think you might regret it later if you don't.

Regret is slightly more difficult to define than it might appear, but most of us would probably agree that it is a sort of negative emotional or cognitive state that involves self-blame for an outcome or outcomes of a choice, and a sense of loss or sadness for the unmade choice. Often, regret is accompanied by wishing – to no end – that we could undo whatever it is we regret having done.

Pointless

Sometimes, regret can be useful – a rational response to a poor decision – and can help us avoid repeating errors. It can also be stultifying, pointless and, at worst, misleading. Regret’s usefulness is really determined by what we do with the feeling once it arises.

Patterns of repetitive, self-obsessed negative rumination can lead to depression and are not trustworthy or accurate information sources upon which to base future decisions. It can help to determine which sorts of regret are useful by differentiating long- from short-term regret. Interestingly, research suggests that in the short term, we regret actions taken. In the long term, we regret actions not taken.

Short-term regret seems exceedingly useful. Regretting an action instantly or soon after the fact is relatively straightforward because the mistake resonates and we know that the action is incompatible in the present with who we actually are or what we actually want now. This provides an immediate opportunity to learn – “I regret loaning my unreliable friend money because she hasn’t repaid it and it has affected our friendship. I won’t loan her money again.” Short-term regret can teach us good lessons.

Long-term regret is more complex. It seems to presuppose that the ‘me’ of now is the same person or individual as the ‘me’ then, when this is not straightforwardly true. Physically and mentally, we are not the same individual at 65 as at 22. It is hard to know whether we are simply imposing the standards, tastes and wishes of now-me on then-me. You might think “I should have gone back to do a master’s degree when I had the time”. What were your reasons for not doing it then? And do you think, in retrospect, that you had either the inclination or the capacity to overcome those reasons at the time?

Undo an action

Retrospectively wishing that you’d wanted something different 20 years ago seems futile. Long-term regret appears sketchy, like trying to testify in court about a crime you witnessed long ago. Memory isn’t reliable, and we cannot help imposing the thoughts and feelings we have about the event now onto our memory of the event then. This form of regret is a retrospective wish to undo an action you took when you thought differently, and is often not helpful.

For long-term regret to be useful – or be a reasonable response to a decision or action – we have to presume that we had either capacity and/or sufficient information to make a different choice at the time. If you were happy with the decision for some time, but began to regret it when your circumstances or outlook changed, then it may well be futile regret.

We often dismiss our former selves as less competent, but if they made a considered, informed decision relevant to their circumstances at the time, your regret now might be misplaced. If they didn’t, torturing yourself now seems damaging. Only when regret is a chance to learn should we hold it close.