"I don't need to strain: what you're saying - that you can look a bunch of people, and based on their faces and clothing, decide they're not American - is racis

"I don't need to strain: what you're saying - that you can look a bunch of people, and based on their faces and clothing, decide they're not American - is racist." No I didn't. In your straining, you are claiming a stronger statement than I made. Again, yet again, one more time, this time just for you, and read carefully, I said that if some person X has been in the US for a time too short to become a US citizen, then a US citizen can easily detect that person X is an immigrant. In particular, there were years where a US citizen could walk into a STEM class and on the first day conclude that the majority of the class was recent immigrants, conclude that he didn't 'fit in', turn, and walk out. Why could a US citizen do this? Because the class had a lot of immigrants only recently here. If the students in the class had all been in the US for a long time, then a US citizen could not accurately detect that they were immigrants. Or, if you are a medical doctor working in an emergency room and a person comes in bleeding profusely, then you can detect right away that he has a serious medical problem. But this does not mean that you can detect everyone with a serious medical problem right away; indeed, the ER and the hospital are packed with diagnostic means for detecting who has a medical problem. That is, being able to detect an obvious medical problem is not the same as being able to detect all medical problems. You mentioned that some people in the US for a long time and non-US citizens can make the same detection. True. I did not say that a US citizen could detect all immigrants. It's a simple matter of a logical statement and has nothing to do with racism. You are not reading the logic correctly. Uh, try to avoid courses in advanced mathematics based on theorems and proofs.