Large inequalities in wealth always threaten the viability of true democracy, since wealth is the basis of political power, and true democracy depends on the equal distribution of political power among all citizens.
Conclusion
Large inequalities in wealth always threaten the viability of true democracy.
Evidence (since / and)
True democracy depends on equal disitribution of political power, and wealth is the basis of political power.
Evaluate
This seems like a pretty reasonable argument. The premises seem to combine a couple rules that come together to give us the conclusion. There are repeating symbols (wealth / political power / true democracy), suggesting that this could be a good contender for diagramming.
The conversational essence is saying, .
Symbolically,
X depends on equal Y. Z is the basis of Y. ----------------------- So, variations in Z will threaten X.
Goal
Let's be picky on a first pass and try to match the essence and the structure, and then if we need to we'll get more flexible on the second pass.