So, we now have some kind of nice, tidy explanation for different characters among different groups of people. Okay. We have a theory. It has explanatory power. What can we do with it? Unless you're willing to commit to eugenics of some kind (be it restricting reproduction or genetic alteration), not much of anything.

I think the first thing politicized HBD advocates would say is to restrict immigration, as this is less controversial than eugenics. Of course, (a) there are many other possible reasons to worry about immigration and (b) you can choose to filter only immigrants with good jobs (at the risk of brain draining the origin country if HBD is true).

HBD doesn't make any predictions at the individual level we couldn't more accurately obtain through listening to a person speak for five seconds, it doesn't actually make any useful predictions. It adds literally nothing to our model of the world.

Firstly, you need more than five seconds to assess someone's intellegence, otherwise job interviews would be over very quickly.

Secondly, it is difficult to assess things like propensity towards criminal behaviour, since anyone can claim not to be a criminal.

Thirdly, and of most generalisable importance, sorry if this sounds insulting, but either you do not understand Baysian probability, or more likely you are ignoring it due to motivated cognition or speaking hyperbolically. If HBD is true, then the group intelligence is your prior, the conversation provides more information and allows you to update to a posterior. I agree that a conversation could provide more information on IQ than HBD (assuming for sake of argument that HBD is true), but just because you have updated does not make your prior useless.

If you think it's true - okay. What does it -add- to your understanding of the world? What useful predictions does it make? How does it permit you to improve society? I've heard people insist it's this majorly important idea that the scientific and political establishment is suppressing. I'd like to introduce you to the aether, another idea that had explanatory power but made no useful predictions, and which was abandoned - not because anybody thought it was wrong, but because it didn't even rise to the level of wrong, because it was useless.

Ok, ignoring HBD for a moment, on a scientific level this is just wrong. To take a less inflammatory example, suppose vitamin B12 increases lifespan, but its a very small effect only apparent over a very large number of people, and you get far more information from diet. Therefore, by your logic, B12 is useless and has the same scientific status as aether.

There are other theories which are certainly useless at our current level of understanding and technology, such as superstrings, or Hawking radiation. These theories are useless, in that we can't extract energy from a black hole using Hawking radiation, and we won't be able to for the forseeable future. This doesn't make Hawking radiation 'not even wrong' because the truth of theories is not determined by whether you think they are useful. The aether theory was abandoned because people thought it was wrong - when it was replaced by relativity, relativity had no use (at least for a few decades). You are comparing the aether, which makes no predictions, with HBD, which does make predictions, although you do not think these predictions are practically useful.

Again, I'm sorry if what I've said seems insulting, but in your haste to take down HBD you are also getting rid of probability theory and the scientific method. You are confusing practicality with truth and 'comparitivly low information' with 'zero information'.