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Bill_McGrath comments on Undiscriminating Skepticism - Less Wrong
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Does this principle apply just to statements concerning intelligence? Or does it apply to any perceived racial difference which may be due to genetics, in part or in whole?
Also, does it apply only to human racial groups? Or does the same thing apply to all biological groupings?
Perhaps, but I think that when discussing things on this discussion board, the statement "Group X is more Y than Group Z" can be reasonably understood to mean that if you measure quality Y, then in general and on average, members of Group X have a higher measurement for Y than members of Group Z. Further, it doesn't imply that every last member of each group has been measured.
Certainly that's what I mean.
I reckon the principle applies in general - there's too much diversity within the classification "black" for it to be particularly useful, I reckon. Perhaps if it was geographically specific, it might be more useful.
It applies to all biological groupings that are sufficiently broad.
So the same reasoning would apply to the categories commonly referred to as "worms," "birds," "penguins," "bears," "elephants," "baboons," "chimpanzees," "rats," and "mice," Agreed?
I see your point but I'm not sure I agree. Perhaps I'm just reluctant to think in those terms, but I don't think that's it. I'm not thinking of this in terms of PC, just in terms of usefulness.
I'm having trouble thinking up an analogy to explain my point; I'll think about it and see if I can. If not, guess I need to start over.
EDIT: Actually, if we replace "intelligence" with a less loaded or emotive quality, say "height", I think I'd still be inclined not to consider it useful. But as I say, I'll have a think about this.
Just to add a note here: using the "height" example, suppose I told you that research has shown black people were on average shorter than white people. Then, it turns out, that my sample of "blacks" was from the area with the pigmy ethnicities, and if I excluded those from my definition of "blacks" then they were on average taller than white people. This is an extreme example, but here the statement "the mean height of black people is less than the mean height of white people" might be TRUE, but it won't be USEFUL.
This is because your sample of black people contains within it many separate distributions for the same attribute, and simply taking their mean is not helpful. I'm merely saying that in an unhomogeneous group, averages are more likely to be misleading.
Sure, a set of equal numbers of mice and elephants are on average bigger than a set of guinea pigs, but that's not a useful statement. And a generalisation from that particular sample to "short-haired animals are bigger than long-haired animals" would be outrightly unjustifiable from your data.
His point isn't actually very good -- "worms" isn't a single category about which you could make many meaningful statements on average either (well, you try coming up with many non-vague true statements that universally apply to platyhelminths, polychaetes, annelids, nematodes...).
Linneaus coined the taxon vermes to hold any non-arthropod invertebrate. Later, cladistics came along and demolished the idea that it was ever a useful biological group.
Whereas "elephants" consists of just a handful of living species in two genera, so we shouldn't be surprised that they have a lot in common -- and even then, if you over-presume on those similarities when making theories, you'll wind up wrong because you didn't realize the ways in which they can differ.
I don't see what difference this makes. If someone were to observe that "elephants" are generally speaking larger than "worms," the fact that the two categories are extremely diverse would not preclude you from reasonably asking whether the difference was due to genetics.
The statement that "blacks" have lower IQs than "whites" is both meaningful and true.
I do not think you understand biology (either in the context of the race/IQ discussion or in general) well enough for it to be worth arguing with you further.
I disagree. What I'm doing is to take the exact criticisms made of categories like "blacks" and "whites" and applying them to other biological categories in order to show that there's a double standard at work.
What exactly am I missing?
You're missing the fact that people are arguing "but the groups are heterogeneous" when they mean "but the different means might be within a standard deviation of each other because single groups have a spread much wider than the difference between them". That would apply when trying to ascertain whether, say, worms are larger than insects, but NOT when trying to ascertain whether worms are larger than elephants, because the difference between the largest and smallest worms is probably a lot bigger than the difference between the average size of a worm and the average size of an insect. On the other hand, the average size of an elephant is greater than the average size of a worm (any worm) by way more than the biggest worm is bigger than the smallest worm.
Suppose I got together all the worms and all the insects and measured their volume, and found the mean size of a worm and the mean size of an insect. And suppose (I have no idea what the truth is here, but it seems about as plausible as anything else) that I found that on average worms are smaller than insects. Would that be meaningful? I don't think it would be useful to know.
How big an IQ gap are you saying exists? Are we talking as much as a standard deviation? Then maybe it would be important (if true). But if so, genetics isn't the only possible explanation. I'd expect upbringing and class to be very important, as well as quality of public schools where they live, perhaps so much so that a genetic difference, if any, could be completely overwhelmed.
I don't recall anyone arguing that in this thread, but this argument -- to the extent it makes any sense at all -- lacks merit.
Let's take your analogy.
To make things simple, let's assume that there are 100 species of worms and 100 species of insects and 1,000,000 individuals from each species. Let's further assume that there is an animal known as the African Aardvark which eats both worms and insects (and has equal access to all), but eats only individuals greater than a certain size. Now suppose it is observed that the African Aardvark eats 75% insects and 25% worms, and we are presented with two hypotheses to explain this observation: (1) The African Aardvark likes the taste of insects better than that of worms; or (2) the African Aardvark prefers larger individuals to smaller individuals.
In evaluating which of the two hypotheses is correct, is it useful (or meaningful) to know that on average worms are smaller than insects? (And you can assume that the two groups each have a spread much wider than the difference between them.)
I'm not sure what this means. To be sure, genetics is not the only reason for the black/white iq gap. At the same time, there is no non-genetic explanation which (1) explains the gap; and (2) is not ridiculous.
Fundamentally, the point is that reasoning about race should be subject to the exact same standards as reasoning about any other kinds of categories.
In regular life, and even in science, people readily accept categories which are somewhat arbitrary; which are difficult to define around the edges; which contain pairs of elements more different than some pairs of elements, only one of which is contained in the category; and so on.
I think that for various emotional reasons, people tend to get wound up over the categories "black" and "white" but such considerations should not affect rationalists.
I agree with you here; I don't think I'm getting wound up for emotional reasons, I just don't think the category is necessarily a partiuclarly useful one, but for reasons I can't really articulate. (I am not knowledgeable about statistics and the relevant terminology.)
But yes, there's no reason to adopt new rules for reason on any topic - that wasn't what I was arguing, and it's clearly counter-rational.
We'll be all right without formal terminology. I'm not at all sure what it is you're trying to get at, and I'd be perfectly happy with you describing it as a metaphor, or an example, or really anything other than "I can't explain why I believe this."
Excuse delay getting back to this.
Okay, I think I can explain. Let's say that we have 5 ethnic groups under the umbrella "black." All of approximately equal size. Groups A and B are found to, in general, be slightly above average intelligence, C and D are about equal, and E are significantly below. The average intelligence for "blacks" is now below average, and this is mathematically correct, while in reality, 4 out 5 black people you meet will tend to be of average or higher intelligence.
Perhaps this is a common statistical fallacy, but this is what I mean about the classification being too broad to be useful; with such a broad area to work from, with no internal distinctions being made in a hugely diverse category, the data isn't all that interesting or enlightening.
Ok, that makes sense. The next obvious question, though, is why you think that the category of people labeled "black" fits this pattern, instead of, say, a Gaussian distribution.
Well, I don't neccessarily think it does fit this pattern, I'm just saying it's a possibility, and there's no particular reason to consider it an unlikely possibility. On the other hand, seeing as the argument linking race to intelligence seems to be based on genetics, I feel that there is too much of a broad genetic sample within "black" for race to be a reliable indicator of intelligence, as I outline above.
I think this is, in fact, a common statistical fallacy: using the mean instead of the median to represent "average".
Median is often better, but not always - it depends on the purpose you wish to put the data to. With anything less than the full distribution, you'll be able to hit some cases in which it can mislead you.
Edited to add:
Specifically - if you are interested in totals, mean is usually a more useful "average". Multiplying the total number of water balloons by the average amount of water in a balloon gives you a much better estimate (exact, in theory) with mean than with median. If you are interested in individuals, median is usually better; if I am asking if the next water balloon will have more than X amount of water, median is a much more informative number. Neither is going to well represent a multimodal distribution, which we might expect to be dealing with in the great*-grandparent's case anyway if the hypothesis of a strong genetic component to variation in intelligence does in fact hold.
Ah; so I'm misunderstanding what brazil84 means by average?