I can't get a signal <a href=" http://visitorsvoice.se/accutane-20-mg-mild-acne.pdf#effectually ">accutane 20 mg twice a week</a> You didn&#8217;t answer the question, but the comparison is completely apt. Newtonian mechanics has a certain range of application, quantum mechanics a wider range of application, and so on, but no physical laws are exceptionless (there are always cases where they break down). Likewise, econ 101 has a certain range of application, but because social phenomena are much more complex, the exceptions are much more numerous and varied and often much more difficult to determine. More advance models and concepts are introduce to deal with these exceptions, just as in physics (or any science, really; I could have chosen biology, chemistry, or psychology and come up with a similar comparison).