Do you mean Spinoza or Leibniz given their knowledge base and upbringing or the same person with a modern environment? I know everything Leibniz knew and a lot more besides. But I suspect that if the same individual grew up in a modern family environment similar to my own he would have accomplished a lot more than I have at the same age.
the same person with a modern environment
They wouldn't be the same person. Which is to say, the the whole matter is nonsense as the other replies in this thread made clear.
If you know more Eliezer Yudkowsky facts, post them in the comments.