'In some cities I have found blacks to be particularly aggressive sometimes.' 'In some cities I have found whites to be particularly aggressive sometimes.' Which, if either, of these statements is racist and why?

neither one is racist because you are just reporting on your observations ... if you had said "Philly is a bad place to be because of all the blacks" or "Salt Lake City is boring bc of all the whites", then yeah, that's racist

I think that both statements are opinions. I do not think either statement is racist. I would have to see more from the person making the statement(s) to deem them racist.

If the person said "blacks are aggressive" or "whites are aggressive" then I would say that they are racist statements.

IF, however, one statement is deemed racist, both would be equally so.

neither,they are just observations

None. The statements are just generalizations. And they balance each other to be racist statements.

+4 Neither of them is racist. They are just generalized observations about groups of people in various locations.
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No doubt many people will answer that they are both racist as this seems to be a lot of peoples favorite fixation these days. In fact it seems that even thinking a racist thought these days is worse than committing multiple rape and murder.

They are both racist because you made a comment about a group of people which could not be true of all that belong to that race.

The first one, because ( I believe) there would exist a reasonable number a black people who would find it racist ( with some assumptions).