In philosophy, e.g. in Spinoza, there is the Latin word "potentia" that is often translated as a power, or capacity, to act (potentia agendi) and to suffer actions.

I am wondering what is the right declination of "potentia" in a sentence like this: "George is violent in potentia." By this sentence I mean that "George is capable, by means of his power/potentials/capacities, to commit violence and to suffer violence."

So, what is the right form of "potentia" in the combination "in potentia"? Is it "in potentia" (ablative) or "in potentiae" (dative)? Or is the preposition "in" wrong and it is "qua potentia" or "per potentia" or something like that?

If we wouldn't use potentia but potestas, would we say "in potestas" or "potestate" (without "in")?

Note: I'm not aiming to translate the whole sentence, but I am actually using the Latin phrase "[in] potentia" in a German or English sentence. Still, it needs to be in the right declination.

Thanks a lot!

  • I'm leaving this as a comment because I'm not sure enough of my own skills yet, but since potential is something that George has the you would use genitive singular: Potentiae.
    – Adam
    Feb 12, 2020 at 0:48

1 Answer 1


“In” with the ablative describes a location, time, or steady state, whereas with the accusative it describes a direction. So the ablative is the appropriate case here, as you want to describe a figurative position, or state. “In” never takes the dative (nor does any other preposition).

The phrase you propose looks good to me. A precedent for it is found in the work of Thomas Aquinas, the medieval philosopher, who, in his Summa Theologiae, develops a view of things having properties in potentia or in actu. For example, he writes about temperature:

quod enim est calidum in actu, non potest simul esse calidum in potentia, sed est simul frigidum in potentia

for what is actually hot cannot at the same time be potentially hot, but is at the same time potentially cold

One might ask if the preposition is necessary and I suppose it is not. On occasion Thomas Aquinas in fact uses the ablativus absolutus actu like this:

… ignis facit lignum, quod est calidum in potentia, esse actu calidum

… fire makes wood, which is potentially hot, be actually hot

This would not look particularly good in English (“he is violent potentia,” what?), so I would recommend keeping the preposition.

I will add that (a) this is of course somewhat esoteric philosophical terminology, and (b) this is medieval Latin, not classical. The classical meaning of potentia goes more in the direction of power and rule; another word like facultas might rather be used.

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