is a general term meaning "regarding the surface", often metaphorically. Both in the literal as in the metaphorical sense the term has often a negative connotation based on the idea that deeper parts are also important to consider.
Thus the term is used to describe an observation or analysis that deals only with the most apparent and obvious features of some object, or phenomenon.
A superficial, or alternatively, an "over-simplified" argument is prone to many logical fallacies: including hasty generalization, division, composition, pathetic fallacy and many others.
A person who exhibits a "superficial" comprehension of some or many subjects may be negatively attributed as being shallow.