Does socialism violate the incentive principle in economics?
nope. plenty of people go to public school, allow roads to be repaired with their tax money even if the roads don't go right by their own homes, use the u.s. postal service (which is written into the constitution) and much more, and STILL manage to be highly motivated in their fields of interest, education and/or employment. socialism isn't something that kills motivation, or even kills free enterprise. it doesn't have to stand alone, and it doesn't, in fact, stand alone. i will add that it's not even a THING, really; it's more of a range. it works very well with democracy, which is certainly more than i can say for capitalism.