It varies from person to person. Someone who is in tune with
his/her own feelings will tend to have a greater ability to guess
the feelings of another, because he/she will be able to read the
signs. (Although, this is all just my own speculation, I suppose
this is why introverted people can seem more empathic and
sympathetic.)
There's also something called "Cold Reading"; I find I can do it ok
enough, but it takes a lot of practice, and you'll need to be very
slick in talking (in case you make a mistake). See Wiki for
details.
Reasoning will not kill empathy or feelings. However, if one is too
logical and direct, it will "kill" feelings, like
you said. Sometimes, intuition just works best.
