• All of them are empirical, because all of them investigate observable facts related to human actions such as behaviors, images, voices or states.

• All of them are systematical because all of them refuse arbitrary, defective, inadequate studies and all include rigorous and meticulous studies.

• All of them are theoretical because although the nature and purpose of theories are different for each approach, none of the approaches claims that the social world consists of chaos and disorder; all of them defend that explaining or understanding
the social world is possible.