Final answer:
The rhetorical device used in the sentence from Common Sense is a rhetorical question, which emphasizes the idea that moral virtue alone is not enough to govern oneself.
Step-by-step explanation:
The rhetorical device used in the sentence from Common Sense is rhetorical question. A rhetorical question is a question asked for effect without expecting an answer. In this case, the question "Here then is the origin and rise of government. We cannot govern ourselves by moral virtue alone." is used to make a point or to emphasize the idea that moral virtue is not enough to govern oneself, implying that government is necessary.