Because it gives people a bad feeling in their tummy :(

Well, there are a number of definitions of the word, but I personally like "the preferential treatment of one or more races above one or more others".

Racism is wrong because your race in itself does not affect your ability to do anything. It is true that members of certain races are, on average, better in certain aspects than members of other races, but that is not to say that every individual of that race is better than every individual of the "inferior" race.

You are judging somebody based on irrelevant criteria and generalising. You are not giving them a chance to show their true ability. You are not taking the time to learn about them as an individual. That is why it is wrong.

Let's take a specific example: choosing from a pool of applicants for a job. I would argue that it is immoral to give the job to anybody except the person who will fit in and succeed best at the company. That means it's immoral to give it to one of your friends, it's immoral to assume a black person is stupid (without looking further at him) and reject him, it is immoral to hire a black person to fill a quota.

Why is that immoral? I have no idea, that just seems like common sense to me, and the reductionism has to stop somewhere.

You say you don't. And you probably don't think you do either. But can you really be sure? I mean, suppose (again, humour me) an alternate reality where you did bring in biases into logical debates. Considering it would be entirely subconscious, would you really know? Do you really know right now?

Anyway, I more or less covered your response in my other post, didn't I? You have your studies, anyone with five minutes and Google could find an equal number of studies that disagree. (And this goes for any topic, really.) Sure, you'll point out the inaccuracies with opposing studies, show how they're biased, not well undertaken, have dubious methodologies, etc. But again, the other person will point out some minor inconsistencies with your studies. At this point, even if you're still convinced that you're more likely to be right, given that you have opposition and some objections to your studies, surely you can't say with absolute certainty that the number of smart males exceeds the number of smart females? And if there's even a degree of uncertainty, you really can't pass something off as a fact, can you?

I think this argument is a good example of why racism is wrong.

Regardless of the facts, racism and sexism is wrong because it invokes the feeling of being treated unfairly. This negative feeling is often felt when others are treated unfairly or when oneself is being treated unfairly. These co-called facts of life are irrelevant. 

I think the first thing to note is that racism is voluntary. You cannot be involuntarily, or unknowingly, racist. If somebody holds prejudicial views, that's still bad, and the person is ignorant and prejudiced, but racism implies malice as well as ignorance. So if you have to (sincerely) ask if something you say is racist, then while what you're saying may be racist, you yourself are not a racist.

As for your evidence: IQ is not really a measure of intelligence, because intelligence, unlike height or weight or 100m sprint speed, is not really a single characteristic. It has many forms. Based on a number of these studies, however, you would be able to state that white people were better at IQ tests than black people, which could potentially stretch to "better at mathematical logic" depending on the consistency and content of the tests. That would not be inaccurate or ignorant, and certainly not racist.

The trouble with obtaining such a study is that black people are, on average, considerably less well-off than white people. It is far from easy to find a sample that controls for everything except race.

It is also worth noting that the majority of scientific and technological innovation in the last millenium or so has come from Europe and North America, but this is getting onto pretty unsteady and speculative ground, so I'll leave it there.

Regardless of whether it's immoral it's definitely economically inefficient to award jobs/scholarships etc. to less than the most qualified and appropriate person to apply.

Very true.

I suppose it's partly that and partly my belief that it is moral to treat everyone with respect until they show that they are unworthy of it.

Because it is mass stereotyping. There is no scientific study that concludes that every single person in a given race is dumber than the dumbest person in another race. If that was somehow proven to be the case, then you could make an objective claim stating "Race X is superior in IQ in Race Y". That is of course assuming you are taking into account one's innate IQ only and not the intelligence they gain throughout their lifetime, because intelligence can change depending on how much effort a person puts into learning. I of course did not mention subjective things such as "beauty" which no one will unanimously agree on.

You'd find that making such a claim of IQ is downright impossible given the fact that we have no absolute way of determining the IQ of a person at birth (at least at the time being) and hence if you made that statement without proof, you'd be bandwagoning people to a stereotype just because a certain set of people act in a certain way. Even if 99 people out of a 100 people acted in a certain way, it'd be wrong to bandwagon that one guy with the other 99 just because they have some other similarity.

So the ultimate point is, stop being racist and get to know people and judge them on their individual merit. Humans are all born unique because of the mechanics of genetics itself.

Where do we draw the line though? You're saying that I shouldn't call blacks less smart (even under the hypothetical situation where this is truth) because it hurts their feelings. I'm guessing I'm not allowed to tell people who have black skin that they have black skin either. Next thing you know, I'm not allowed to say anything to anyone because it "hurts their feelings". Are we really okay with that?

"John, you're wearing a blue shirt today."

"How could you say that? This is making me feel bad. You didn't tell anyone else the color of their shirts. It doesn't matter if it's a fact; I'm not taking this from you."

@Kantor:

I don't intend to harm anyone with my words. Sure, I'm well aware that what I'm saying will offend people, but shouldn't I be allowed to say it if it's true?

Also, you're taking my example far too literally. I personally detest IQ Tests and don't consider them a reliable measure of anything. I know that such a perfect study would be borderline impossible. All this was basically leading to this point, though: what if blacks were, for a fact, not smart? How does that affect the morality of calling them not smart?

For your last comment, I'm leaving that alone, but it's just because I don't think it's worth it starting a completely irrelevant historical argument here. Rest assured, though; I completely disagree with your insinuation and have piles of evidence to back me up. :P

Well it's for nature to decide right?

Just as there are distributions of intelligence among the human race, there is a distribution of the propensity toward being racist. How this effects and interacts with society as a whole, I have no idea. However, through discussion and gossip humans as a society come to a concensus as to what is acceptable behaviour. In North America, maybe we have to be sensitive towards the feelings of others but that's a lot better than being bombarded by missles as in the Israeli-Palestine conflict. These are much different lines. 

Also, something can be wrong, but it doesn't mean you are not allowed to do it. We can debate whether murder is wrong, yet terrorists kill themselves for a righteous cause. In their mind it's right, and for those who suffered as a result it's wrong. In both cases who is right is defined by the feeling of indignation.

The same is true for racism. You can benefit from it, or see that you're in the right, or you can still be morally wrong but be racist anyway. However, when someone feels as though they have been treated unfairly they feel they've been wronged. I'm not sure why anyone would want to live their life knowingly hurting others, but people do it all time. Like in your hypothetical situation, what's the point of saying black people are less intelligent? Regardless of whether or not it's true.