Science is the never-ending struggle to find truth. You may dismiss this statement as the

rambling of an amateur philosopher, but it holds some practical value. Truth is a temporary phenomenon. It is limited by human communication systems, technology, and skills. For example, during the Dark Ages in Europe, the world was perceived as flat. This flatness was acceptable as "truth" because travel and human knowledge of celestial phenomena were so limited that no other concept was needed. A family lived in a small area and confined its activity to a small region. This region appeared to be flat, so for all practical purposes, the earth was flat, too. When travel and exploration became widespread, and especially when ships were able to sail far out on the Atlantic, the vision of a flat earth had to change. Many observations of stars and planets and of ships' movements at sea led to new principles and to a new truth. Those who were in the position to do so could exploit the new truth about the earth's shape and turn it into riches. The Spanish, knowing they would not fall off the edge of a flat earth, found the New World and brought gold and silver back to Spain.

The situation has not changed much since the Dark Ages. Truth is still sought because it has value, and the scientific method remains the most systematic way of pursuing it. The method starts with a problem. Once the problem is well defined, information that might have an effect on it is gathered. The information is sorted and analyzed, and that which is useful is kept—to be used as a basis for general principles. In the social sciences, the principles are often used to help formulate policies. The policies ultimately are aimed at removing the problem and improving people's lives.

In economics (and in other social sciences), the pursuit of truth is slowed because human behavior. cannot be subjected to the kinds of controlled experiments that are possible with white rats and guinea pigs. The economist must follow the steps in a search for new truths about economic behavior, but following them is frustrating and often leads up blind alleys. Nevertheless, problems, facts, principles, and policies must be considered in a systematic way.

What can we infer from the fact that the world was perceived as flat？

A．Most people during the Dark Ages were illiterate.

B．People during the Dark Ages were lacking in social knowledge.

C．People today were more knowledgeable than those during the Dark Ages.

D．People's cognition of the world was related to the scientific development.