In the US, Barack Obama is considered black, even though he is half white. If that doesn't give you pause about "race"...

There have been numerous studies comparing genetic ancestry to self identification of race with an effectively perfect mapping. Here [1] [2] are a couple of papers. The reason there are not more papers is because the data here is not even remotely ambiguous. Your position is a semantic strawman -- it claims race references something other than ancestry, and then goes on to argue that that 'something' does not exist. It is the most classical form of a strawman - set it up and burn it down. Race, both in denotation and connotation, is a reference to genetic ancestry.

[1] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1196372/

[2] - https://jmg.bmj.com/content/47/12/835

Could we use the word 'breed' then, instead of race? I guarantee you that if you showed me a mixed room of hundreds of native Danes and Sentinelese - I could classify them as easily as one could classify chihuahuas vs great danes.

    > if you showed me a mixed room of hundreds of 
    > native Danes and Sentinelese - I could classify them

What relevance does that have? Could you reliably tell a Dane from a Greek? How about a Sentinelese from a Pakistani?

When people say "race" is a social construct, they don't - well, unless they're morons - mean that people aren't more different, the more distantly-related they are. It's the categories that are the social construction. Because anyone who really thinks about it carefully enough, can see those categories are arbitrary.

If history had been a bit different, and we hadn't come to lump brown- and blue-eyed people into the same "race," you might have written this...

    > if you showed me a mixed room of hundreds of 
    > native Brundanes and Bladanes - I could classify them

> What relevance does that have?

It shows, at least in this contrived example, that the information is present in the individuals and not in the brain of the classifier.

I don't understand your last point. Is it wrong to say that I could extremely accurately classify blue and brown eyed people?

    > not in the brain of the classifier.

Sure, but you can see physical differences between your paternal and maternal grandfather, too, even if your culture considers them the same "race."

    > to say that I could extremely accurately 
    > classify blue and brown eyed people? 

And why not classify them as deep blue, light blue, hazel, and deep brown? Or blue, gray, and brown? Etc.

The point isn't that everyone's eye color is the same. It's that the classification is arbitrary.

I'm not arguing that race is a useful basis for determining someone's value in society, or anything like that. Merely that it actually does exist, and different peoples at this point in history have vastly different lineages.

I wasn't arguing that you were a bigot. I wasn't denying that the average Englishman is more similar to the average Greek, than to the average Japanese.

I'm saying a belief in distinct "races" of people is bogus.

Actually, Danes and Sentinelese would both be classified as belonging to the same, Caucasoid, race. From the Wikipedia article on Caucasian race:

First introduced in the 1780s by members of the Göttingen School of History,[4] the term denoted one of three purported major races of humankind (Caucasoid, Mongoloid, Negroid).[5] In biological anthropology, Caucasoid has been used as an umbrella term for phenotypically similar groups from these different regions, with a focus on skeletal anatomy, and especially cranial morphology, over skin tone.[6] Ancient and modern "Caucasoid" populations were thus held to have ranged in complexion from white to dark brown.[7]

https://en.wikipedia.org/wiki/Caucasian_race

According to an outdated anatomical taxonomy from the 1700s.

Yes, absolutely. The whole concept of race is obsolete and discussions of it are anachronistic to the extreme. I reckon, the only people who still use those terms in earnest are US law enforcement agents, racist groups and people who just haven't got the memo.

Not just law enforcement, the entire US government does. For example, you will see a question about your race on the 2020 census if you are in America: https://www.census.gov/newsroom/releases/img/person1_hispani...

There are often race-related questions in job applications.

Is that sort of thing legal, in the US? Or is it more like, it's illegal but everybody does it anyway?

I live in the UK, in the EU. Here, it's illegal to ask candidates questions about their race, religion, age, marital status, family planning etc. As it is illlegal to advertise jobs to "white male 30 yrs old" etc.

Of course, people still do stuff like that- e.g. I've been asked about my age a couple of times and apparently it's common to be asked about whether you're planning to have children soon, by interviewers, though this has never happened to me (so it might depend on the industry).

I don’t think the UK is very different from the US in this respect. Discrimination based on race, religion, etc is illegal. Asking race, religion, etc as part of the application process is not illegal. Actually, they are supossed to do it (while preventing those details from influencing the hiring process).

The point is that there is a lot of people who do care about race, not just US cops.

https://race.bitc.org.uk/sites/default/files/kcfinder/files/...

How about instead you try to distinguish between a Tutsi and a Hutu, or a Serb vs a Croat? Because in both cases wars of mass murder have recently been fought over those differences.

Both of your examples are people who even 1000 years ago were considered the same. Tutsi and Hutu differ based on essentially their social class and profession(pastoralist vs farmer), and for Serb and Croat their religion.

Is your stance in life that, if some information has been used in the past for bad purposes, we must pretend like it doesn't exist so those bad things don't happen again?