"Science is a method"

From Carroll Quigley's The Evolution of Civilizations (PDF), pages 40-41

Even today few scientists and perhaps even fewer nonscientists realize that science is a method and nothing else. Even in books pretending to be authoritative, we are told that science is a body of knowledge or that science is certain areas of study. It is neither of these...

Closely related to the erroneous idea that science is a body of knowledge is the equally erroneous idea that scientific theories are true. One example of this belief is the idea that such theories begin as hypotheses and somehow are "proved" and become "laws." There is no way in which any scientific theory could be proved, and as a result such theories always remain hypotheses.

The fact that such theories "work" and permit us to manipulate and even transform the physical world is no proof that these theories are true. Many theories that were clearly untrue have "worked" and continue to work for long periods. The belief that the world is a flat surface did not prevent men from moving about on its surface successfully. The acceptance of "Aristotelian" beliefs about falling bodies did not keep people from dealing with such bodies, and doing so with considerable success. Men could have played baseball on a flat world under Aristotle's laws and still pitched curves and hit home runs with as much skill as they do today.

Eventually, to be sure, erroneous theories will fail to work and their falseness will be revealed, but it may take a very long time for this to happen, especially if men continue to operate in the limited areas in which the erroneous theories were formulated.

I cannot read that without modern-day politics coming to mind.

Quigley continues:

Thus scientific theories must be recognized as hypotheses and as subjective human creations no matter how long they remain unrefuted. Failure to recognize this helped to kill ancient science in the days of the Greeks. At that time the chief enemies of science were the rationalists. These men, with all the prestige of Pythagoras and Plato behind them, argued that the human senses are not dependable but are erroneous and misleading and that, accordingly, the truth must be sought without using the senses and observation, and by the use of reason and logic alone.

Thankfully, that brings me back to econ: 

• The ancient Greeks had "rationalists". Today we have "rational expectations".
  
  
• Those anti-scientific old Greeks "argued that the human senses are not dependable but are erroneous and misleading". Disagree with an economist today and you will receive the same scolding.
  
  
• Those old Greeks thought "the truth must be sought without using the senses and observation, and by the use of reason and logic alone." Today, as important guides to economic policy, we have the natural rate of unemployment, potential output, and the natural rate of interest, none of which is a measurable quantity. All three arise from "reason and logic" alone.