While information can help us make better choices, its acquisition is costly. Therefore, even purposeful decision-makers will not have perfect knowledge about the future when they make choices. Expected benefits versus cost of gathering information. Economic actions often generate secondary effects in addition to their immediate effects. The value of a good or a service is subjective.
Preferences differ among individuals.
The value of a good or service depends on many things, such as who uses it and when, this is why trade creates wealth. How individuals value items is seldom known perfectly. The test of a theory is its ability to predict. Economic thinking is scientific thinking. Economists develop economic theory from the analysis of how incentives will affect decision-makers, and then test the theory against the real world events.