Critics argue that the functionalist perspective has a number of shortcomings. For one, it is a conservative perspective because it seems to defend the existing order of things. Two critics also take issue with the functionalist assumption that a part exists because it serves a purpose: there are too many examples where a part’s function does not become evident until it has been in existence for a long period of time. Third, a part may not perform a function in the most efficient way (e.g., public transportation versus the automobile). Fourth, sometimes functionalists’ explanations can border on the absurd. Finally, functionalists have trouble explaining social conflict and other forms of instability.