Cullen writes an interesting article with a laudable goal, which is making economics an science by purging it of the non-descriptive. However, a great deal has already been written about why this is not possible in the social sciences, which I won't repeat here other than to mention it and say that there are formidable obstacles to accomplishing this, which is why it hasn't happened yet.
The social sciences, as well as psychology, are combinations of philosophy and science insofar as they are interesting and science only insofar as they limit themselves to the strict application of scientific method, which is limited in the social sciences due to the subject matter, for a variety of reasons.
The best we can hope for with existing methodology is to differentiate as clearly as possible between the descriptive and non-descriptive, but this is very difficult due to pesky things like subjectivity and hidden assumptions.
However, it is worthwhile talking about to throw some sunlight on the issues. For example, New Classicalism and Neoliberalism purport to be descriptions only involving the the natural, while critics have pointed out that this is just ignoring unacknowledged assumptions that cannot be reduced to the natural and demonstrated empirically.
Read it at Modern Monetary Realism
The “Dismal Science” and Getting Back to Da Vinci’s Methodology
by Cullen Roche