common sense is the day-to-day problem solving skill, so it doesn't matter if may pinag-aralan o wala since every day nagso-solve tayo ng problem at nakaka learn tayo ng skill doon
however, if may pinag-aralan ang isang tao, ipa-prioritize niya yung systematic solving of problem before sila mag last resort sa common sense
so ang tanong: nawala ba common sense? NO
mas pinipili lang nila ang more sophisticated approach kesa common sense