Breakdown of Decet bonos cives pacta servare et amicos non fallere.
Questions & Answers about Decet bonos cives pacta servare et amicos non fallere.
Because decet often uses the person concerned in the accusative.
So Latin is structured like:
decet bonos cives ... = it is fitting for good citizens ...
That means bonos cives is not the nominative subject of decet. Instead, it is the person for whom the action is appropriate. It is also the understood subject of the infinitives servare and fallere: the good citizens are the ones keeping agreements and not deceiving friends.
Because bonos cives is not the grammatical subject of decet.
The sentence works more like:
It is fitting
for good citizens
to keep agreements and not deceive friends.
So the main idea being stated is the singular idea it is fitting, and that is why Latin has decet, not decent.
In natural English, we often turn this into good citizens should..., but Latin is built differently.
Here decet means it is fitting, it is proper, or it befits.