That doesn't answer my question as to what argument is supposedly attempted to be invalidated by pointing out hipocrisy. The article refers to "...the U.S. gov

That doesn't answer my question as to what argument is supposedly attempted to be invalidated by pointing out hipocrisy. The article refers to "...the U.S. government’s message to China and other nations today...". I understood the author to be saying that said message is wrong. I admit that it wasn't stated outright[1], but I don't think I was misunderstanding the author to read his opening the article by contrasting history with the present policy as a criticism of that policy -- that the implication is that it's wrong for someone to say to do something other than what they did. If you look at the comments here, I think it's evident that a many people agree with that criticism and share that view. I was only pointing out that within the article, that point is poorly argued. It's just sort of taken for granted that "do as I say, not as I did" is obviously wrong. I'm saying that it's not inherently wrong, and--appropriate to the author's discussion of US cotton manufacture in the 1700-1800s--citing slavery as an example of something where "do as I say, not as I did" is entirely righteous. [1] For all I know, the lede could have been tacked on by an editor to make an timely article out of a book excerpt, but that doesn't make it any more right.