My feeling is that it's ok to make judgements on the population and act on that, it's not ok to use judgments on the population to negatively affect your treatm

My feeling is that it's ok to make judgements on the population and act on that, it's not ok to use judgments on the population to negatively affect your treatment of the individual. This is easier to explain with gender differences: It's ok for a company to decide to make financial considerations based on the number of women they employ and chances of maternity leave. It's not ok to not hire an individual based on the fact that they're female and therefore have a chance of needing maternity leave. It's a valid conclusion that on average men run faster than women, but you should assume that in any given male/female pair the man will run faster. It's difficult to know where to set the threshold for 'negatively affect' though. For instance, black men have a higher incidence of heart problems, and different medical decisions need to be taken in that case due a different risk balance. This (to me) is clearly just good evidence based medicine. In this case I'd argue the problem is that 'black' is a signal used in a lot of models, so discriminating on that becomes a large cumulative negative effect so it shouldn't be used. If 'red hair' was a signal in some situation, then that would be fine because people don't normally get affected by that. The rare situation of being stopped incorrectly is outweighed by the benefit.