Suppose that Athens avoids the Sicilian Expedition, thus prevailing with its Delian League intact following a shorter Peloponnesian War; that in later years is only overshadowed as a maritime power by a polis adopting a similar government; and that this democratic hegemony lasts at least four centuries following the PoD (or to the end of OTL's "BCE") -- and JTBC, I'm only looking at the effects of this, not the how (there are
threads and TLs on that).
What would the Mediterranean (and surrounding) societies and polities look like in this time -- would it remain more balkanized into polis', or could larger proto-states emerge? What are the chances that any of the powerful full-fledged democracies (Athens, Syracuse, if it survives, etc) might expand their rolls of voting citizens, be they with the metics, the citizen women, or what have you? How would political (and perhaps general) philosophy be altered? And how else might western civilization be fundamentally changed?
J.F.Parker,
The Sicilian expedition was the only way to shorten the war;in any war involving a sea power and a land power the sea power is the winner in the end if it can effectively blockade the land based power(example:England-Germany).Sparta would carry the war for a long time unless its life line(the supplies from Syracusae and its allies) was cut off(the best solution).
Thucidides affirms that the expedition was so well planned that there was no chance of failure given the superiority of Athens on land and sea.
The Spartans would not have turned the tables but for the Sicilian catastrophe that encouraged Persia to get involved(with gold);had it not been for the destruction in Sicily(your point of divergence),the Persians would never have got involved,since they had a bitter experience from the 460-450 war outcome while Athens emerged victorious on a three-front war against the Peloponnesian alliance,central Greece(Beotean Federation),and Persia;although they managed to repel the Athenians in the Egyptian revolt
their fleets were utterly destroyed by Cimon and their presence in the southern Mediterranean pivot island of Cyprus successfully contested.
As a result intact Athenian armies and fleets would bar Persian involvement from fear of Athenian reprisals for breach of the peace of Callias(449 BC) and no chance of Spartan navy in the Aegean and attrition
that did not favour the Spartans(no commercial activity for Peloponnese-Corinth-Megara,Aegina destroyed by the Athenians,no wherewithal for continuation of the war).
The question was one only:in both cases one person would decide the war:Alkibiades.
If Alkibiades stabilised his position in Athens,regarding his enemies who were waiting for his departure to accuse him impiety(case with the cutting off the heads of the Hermae) the Sicilian expedition would have had one end only after the defeat of the Syracusan army by the Athenians:the fall of Syracusae and the domination of Athens in Sicily.
If the expedition didn't take place,and Alkibiades had the free hand in the Aegean,the war might or might not last longer,but with the same inevitable result.
Extension of citizenship: since it has been mentioned in this thread,the Athenians had already started that,first with the Plataeans and second with their staunchest ally in the Aegean,the island of Samos;others would follow for certain...
Someone mentioned Rome as a democratic state: far from it!someone has to study the role of the comitias in Rome and their legal powers especially that of the Comitia Centuriata and the manner of voting and counting votes in that Comitia;the reference is not in history,but in Law.
see Lee:"Roman Law",also Buckland:"Institutions of Rome" and Roman History.