Why psychology isn't a science

Writing in Psychology Today, Norman N. Holland explains:

The problem comes from the very effort to be scientific. . . . [P]sychological experiments tend to get more and more specific. Experimenters will use exactly defined methods and procedures. They will use highly specific statistical tests appropriate to the experiment at hand. They may select subjects with very special characteristics. All this is, of course, quite appropriate in a discipline seeking to be scientific. But the end result is a teeny, tiny conclusion that cannot be added to other experiments with differently specific subjects, different statistical tests, different methods and procedures. No cumulation. No science....

When I ask my psychology students, What major conclusions about the human mind can you draw from contemporary psychological research?, I draw a blank....

Scientific psychology becomes unscientific because it is dealing with mind, and mind does not lend itself to experimental precision.

Sounds about right. I took a few psychology courses in college, and I was struck by how free the instructors were in stating their random opinions about life as if they were scientific facts. One professor told our class that each one of us in the room could potentially be a victim of a violently abusive relationship, and stay in it on a long-term basis. How could anyone possibly know that?