would defeat/ would have defeated

[dewedfrost]

"P.B. Shelley thought man's good nature would defeat/would have defeated evil":
I can't understand the difference between the two verb forms: which is the correct one?
The sentence comes from a kind of translation from English into Italian of a brief introduction to the English Romanticism . Help me, please!
I think "would defeat" could be the right option: do you agree? Which is the difference between the two forms? Thanks a lot in advance!

 

[MikeNewYork]

The choice depends on context.

 

[Tdol]

I'd guess that Shelley was looking ahead, in which case would defeat would work. But, as said above, the context is essential.