The title says it all: What would be the world look like if the Persians under Darius I had successfully conquered the Greek city-states and made Greece into a satrapy? Could this mean that the West (or what arises in Europe in its place) become overall and customarily more open to new ideas and more tolerant than in OTL? Maybe, much later, no Transatlantic Slave Genocide, as the Persians famously banned slavery?
Discuss.
I have to be curious, what would you describe as more open to ideas and tolerant? I'd have to say that compared to other groups throughout history, we were no more significantly intolerant or close-minded than other cultures of the time, I'd love to see some "benchmarks" to compare against at different points in history. (In addition - there idea of the west is recent, is this meant to indicate lands of the modern west? Europe, N.America?)
As I'd expect the Persian hold on Greece to be tenuous, I can only imagine their cultural effects to be negligible. Slavery may well be introduced via a new conqueror of Greece, or of Persia (in the same way as the Parthians are meant to have done).
I'd love to see Greece not have slaves, but I am very doubtful that a Persian conquest would achieve this, unless it is held for a very long time, and that Persian attitudes don't change - that we don't see a successful slavocracy like Rome, etc. So I have to say, no I don't think that would change.
Tolerance and openness to ideas? Again, this entirely depends of the interim, we could see any number of anti-intellectual scholars gain followings - as is widely touted to have happened in Baghdad - I forget the name, which maddens me.
In addition, we could see rises of Nazi analogues, of Imperial Japanese analogues.
There is FAR too much time in between.
If you wanted a more open-minded and tolerant west, you may want either a large-scale conquest of Europe by such a polity. My choices would be
1) Super-Achemanids - It'll be hard, and unstable as hell - but assuming they were as anti-slavery as believed, this is the hardest option.
2) Alexandrian Empire - Considering his love of Persia after he conquered it, he may be against Slavery, in addition, unlike Plato in 'The Republic' I do recall reading the Phillip opposed slavery, and the Macedonians were much more like the Persians in this regard. If this expanded westward, and held these virtues, even if he loses Persia - this could work.
3) Non-Enslaving Roman or Carthaginian Empires? If the Roman Empire was anti-slavery, or some analogue with similar success was, chances are that this would have the biggest advance, as much as there is a more recent flirtation with Greece, it was Rome that had the largest impact on the west.
4) Macedonian Hegemony of the Med. If we assume Phillip Lives, and only takes territory we associate with the ERE, Macedonian views on slavery would begin to prevail - if Greater Macedonia and Persia can not destroy each other, this could lead to more anti-slavery support.