> The saving gap perspective tells a contrary story. Investment spending would have been lower if not for the United States being able to borrow from the rest of the world. One can argue that this funding raised the economy’s productive capacity from what it would have been otherwise.
This sounds backwards, I suspect he's being a bit sloppy when he says that. To sustain the trade deficit it was necessary to enormously increase China's productive capacity so that they could build the goods that get shipped to the US. If the US wasn't running a trade deficit the number in the statistics might have been lower, but it is quite likely that the amount of productive capital actually built in the US would have increased and they might have the same amount of real stuff at the end of the day. They could have built a similar amount of production in the US, for example, instead of importing. The accounting identity for that might be a lower number but that doesn't immediately tell us anything about what the real outcome would have looked like.
It is like the situation where nominally China's economy is nominally smaller than the US's, even though as far as the economists can tell China produces more actual stuff. Accounting identities are so basic that they abstract out a lot of important detail vis a vis what an outcome looks like on the ground. Accounting identities always hold, so any situation that can theoretically occur will have a valid accounting identity. It doesn't make sense to rank outcomes by how high investment spending is, it is important to know what real changes would occur. Which identities can't tell us because they are general.
Obviously he is technically correct that he can argue that, but it is insinuating a relationship. This stuff is the bane of central planners, it is nearly impossible to tell in the abstract whether a change in accounting identities was good or bad for productive capacity.