The author concludes that if there has been a true democracy, it must have been in ancient Athens. Why? Because in ancient Athens, the legislature consisted of all eligible voters, and this wasn’t true for any other political system in world history. This meant that in Athens, individual voters made all political decisions by direct vote.

We’re trying to prove that if something was a true democracy, it must have been in ancient Athens. But none of the premises tell us what’s required to be a true democracy. So at a minimum, we know the correct answer should tell us what’s required for a true democracy.

We can go further to anticipate a more specific connection. What was the quality that was found only in ancient Athens? The legislature consisted of all eligible voters, who made all political decisions. If we can establish that in order to be a true democracy, a polical system must have the quality that was found only in ancient Athens — legislature consisting of all eligible voters, who made all political decisions — then we will prove that only ancient Athens could have been a true democracy.