Attempting to resuscitate a child, failing, and then going about one’s day is neither ruthless nor cruel, but I think I understand what you mean. It can be jarring for some people when doctors are seemingly unaffected by the high intensity situations they experience.
Doing good does sometimes require overriding instincts designed to prevent evil. For instance, a surgeon must overcome certain natural instincts not to hurt when she cuts into a patient’s flesh and blood pours out. The instinct says this is cruelty, the rational mind knows it will save the life of the patient.
There are hazards involved in overriding natural instincts, such as in C&P where the protagonist overrides natural instincts against murder because he is convinced that it is in the greater good, because instincts exist for good reason. There are also hazards involved in following natural instincts. Humans have the capacity for both.
Following instincts vs. overriding instincts, both variants are appropriate at different times. Putting correctly proportioned trust in reasoning vs. instinct is important. You need to consider when instincts mislead, but you also need to consider when reasoning misleads.
It would be a mistake to take a relatively clear cut case of the doctor’s override of natural sympathetic instinct (for which there is a great deal of training and precedent which establishes that it is a good idea) and turn it into a generalized principle of “trust reason over moral instinct” under uncertainty. There is no uncertainty in the doctors case, the correct path is obvious. Just because doctors are allowed to override instincts like “don’t cut into flesh” and “grieve when witnessing death” in a case where it has already been predecided that this is a good idea doesn’t mean they get free license to override just willy nilly whenever they’ve convinced themselves it’s for a greater good, they still have to undergo the deliberative process of asking whether they’ve rationalized themselves into something bad.
I agree, although, given the same training you speak of, I think in their cases it is almost “instinct vs. reasoning”, and so is not as hard a choice as it could be. (I also might be less unwilling to cut into flesh than other people, having had surgery myself and retained a mild interest in zootomy since my school years, so there’s that.)
And in C&P, as I recall, Svidrigaylov blackmailed Raskol’nikov quoting Raskol’nikov’s own words that the prostitute’s younger sister would go the same way...which might have been the first instance when I learned that people should care not to leak information, whether it be a statement of facts or a statement of their attitude to facts, however morally good it is. So now I take my observations with a grain of salt; and I want to trust my eyes, but that’s about it...