In economics, it is assumed that all human beings are rational.
We have to think “rationality” and “economical rationality” separately.
If whether news tells you that today will get rain, you will bring your umbrella.
It’s a rational action. (You will not put aside the news caster’s advice.)
If you will have English test and Math test, and you are good at English but poor at Math, then you will study Math harder than English to get totally good point.
It’s a rational action. (For the aim to get totally good point.)
“Rational action” means “making action for some aim you set based on some information you can get in a point of the time.”
Then let’s move on to next example.
In front of you, two chocolates A and B are there.
A is 1 dollar, and B is 3 dollar.
B is more expensive because it is made by fair-trade.
Which would you buy?
If you want cheaper one, you would buy A. It’s rational action along with your purpose.
If you want to save developing countries from poverty, you would buy B. It is also rational action.
“Rational action” would be change depends on your purpose.
Economics only deals with rational action for economical purpose.
So it assumes “human beings are economically rational.”
General criticisms for economics; “Human beings are not rational! Assuming rational people is nonsense!” contains some misunderstanding.
Economics just deals with “economical rationality”, it doesn’t say that all humans behaviors are economically rational.
On the other hand, a lot of economists also have misunderstandings. People don’t behave as economic rationalist in actually, as for people have various kind of purpose for making their decision, but I think almost all the scholars and students who majored economics tend to think that people make an action along with economical reason.
We have to know which part of the phenomenon of our society the learning spotted light.