How to translate "He who can, must"?

Question

We are a couple in our mid seventies. We want to remain relevant. Our company tag-line is "Feeding the urban population within urban boundaries" Our way of doing this is to use the light spectrum effectively for growing food in covered environments. Lots of highly sophisticated electronics. Our friends (and enemies) wonder why we care, when our lives are at the pointy ends. Our response is that we do it because we can, and we think we should. We will not see much of the results.

So we would like to have the motto "he who can, must" or similar in Latin. One of us is a word-nerd; the other not so much.

Answer 1

I have three suggestions:

1. Potentis est facere.

2. Qui potest, debet.

3. Si potes, fac.

The first one is "it is of the able to do", which in more fluent English would be "it is the duty of the able one to do". This is singular; if you want several able ones, switch the first word to potentium.

The second one is more straightforward, "[he] who can, must". The word debere has many meanings, e.g. "owe money" in addition to "must", but ambiguity is common in a concise motto.

The third option is a direct order: "If you can, do." It really reads as an order rather than a description, so it feels different and quite strong.

I find the first one to be of better style, but it's a matter of taste. Let me know if you have any questions on details, nuances, or options.

Answer 2

I would suggest:

Cui faciendi potestas, eidem faciendum est.

Which means:

"He who has the power to do it is the one who must do it," or "The one who is able do it is the very one who's got to do it."

This is much less pithy than “He who can, must,” but I think more precise—perhaps a little too precise for your purposes.