Taxation is the oppressive practice of taking other people's hard-earned money." identify the rhetorical device involved here.

Rhetorical explanation or definition.

Here, the reader is supposed to agree with the author's sentiments and negative opinion of taxation (through the use of the "charged" words such as oppressive and hard-earned). Rhetorical explanations often convey a certain feeling for the reader; here, the reader feels the negative and unjust feelings regarding taxation.