There are a number of different circumstances when it’s important to distinguish between reversible and irreversible decisions. First, though may seem pretty obvious, let me be clear by what I mean by each of those.
A decision is only irreversible if there’s absolutely no way to take it back again. The somewhat clichéd example is that you can’t un-ring a bell. However, there are plenty of more consequential decisions which are also quite permanent. Drive drunk? You may not have an opportunity to repent of that decision. Unprotected sex? You might have no way to undo the damage you’ve done to your body.
Fortunately, most decisions aren’t completely irreversible: although they may be more or less difficult / expensive to fix. Get married to the wrong person? That could have massive consequences, but it’s possible to fix. Paint your house a color which turns out to be ugly? Probably less difficult to unwind, but still not consequence-free. Get a bad haircut? You’re out a little bit of money, but it will fix itself in time.
And, of course, there are a huge number of decisions we make every day which are completely and readily reversible. Not enjoying the channel you’re watching on TV? Just flip to the next one.
One way to use this distinction is to guide you in how much effort to spend ahead of time trying to make a certain decision. When I find myself faced with a decision, part of the process is to make exactly this evaluation. If it’s a pretty reversible decision, I won’t let myself get too caught up in making it. I choose the first option which seems pretty reasonable, and I move along. On the other hand, I’ll spend quite a bit of time evaluating houses before buying one, and even more when considering changing jobs.
Another useful way to use this distinction is when you’re responsible for guiding another person (e.g., as a parent, guardian, coach, manager, executive, etc.). If a decision is reversible, and your other person is set on making a choice you’re skeptical of, perhaps you let them go ahead anyway. If they’re wrong, then they’ll learn something from the attempt in much deeper way they might have done. If they’re right, then you’ve learned something instead. On the other hand, for a more irreversible decision, you may decide you need to intervene (e.g., a toddler climbing upon on a coffee table vs. running out into the street).
Finally, this distinction can also be useful when trying to make a decision as a group. As it often happens, different people will offer up differing suggestions on how to proceed, and the best answer isn’t always clear. In such cases, it can be very helpful to gauge how reversible the decision is. When it’s pretty easy to back away from, it’s fine to just pick a solution (probably from the most insistent person in the group), and see how it works out. On the other hand, if it’s a fairly irreversible decision, you may all way to slow down, gather more data, and try to be a lot more careful.