Philosopher: Some of the most ardent philosophical opponents of democracy have rightly noted that both the inherently best and the inherently worst possible forms of government are those that concentrate political power in the hands of a few.
Conclusion (thus)
Democracy is a better choice than rule by a few.
Evidence (since)
The inherently best and the inherently worst forms of government are those that concentrate political power in the hands of a few.
Democracy is consistently a mediocre form of government.
Evaluate
The argument chooses one form of rule (democracy) over another (rule by a few) and it provides one detail about each. The argument assumes that a form of rule that is consistently mediocre is preferable to one that could be either the best or the worst.
When the argument involves a positive thing (you won't get the worst) and a negative thing (but you also won't get the best), we generally see a comparative answer that is Weighing Tradeoffs.