The core argument of this book seems to be that found in Chapters 1-4: That the "STEM shortage" is a myth, and that people over-state the need for advanced math even in a lot of STEM jobs. There's a lot to be said about that, and about the distinction between numeracy and advanced math. Those subjects deserve their own series of posts, so I'll delay those. For now, I just want to address something in Chapter 6:
In Chapter 6, I think Hacker is trying too hard. He starts by going after a common argument: That learning math is good for your overall intellect, and in some way unique to math, some way that other disciplines don't possess. I will agree with him that mathematical thinking is simply one way of thinking and not THE way of thinking. However, when he tries to claim that nobody makes a similar argument for humanities, he goes too far. Has he never read any of the numerous essays on how studying humanities makes you a broad-minded critical thinker, unlike those nasty, narrow STEM disciplines? There's a lot to be valued in humanities and social science, but let's not pretend that they don't get in on the "We're the REAL smart people" game.
On the other hand, I like his point about how mathematics, unlike some academic disciplines, can thrive even under despotic regimes. I don't consider that a BAD thing about math--I think it's great that there are some wonderful, beautiful areas of inquiry that even tyrants do not try to eradicate. But it also tells us something about how unthreatening many areas of STEM are for those in power. We might do well to ask ourselves why that is.