Co-blogger Scott Sumner got into a discussion about Thomas Piketty's views about what the top marginal tax rate on income in France should be. I've read his book Capital in the Twenty-First Century thoroughly and reviewed it at length. I don't recall Piketty's addressing that issue directly. But he does seem to advocate a top income tax rate for Americans, and for people in richer countries, of about 80 percent. Here's a short excerpt from my review:
He argues briefly that the optimal top income tax rate in richer countries is "probably above 80 percent." He claims that such a rate on incomes above $500,000 or $1 million "will not bring the government much in the way of revenue"--I agree--but will drastically reduce the compensation of high-paid people.
If you want to read more about his thoughts, go to pages 512-513 of his book.
So I would bet that Scott is right that Piketty did not oppose the 75% income tax rate in France.