It seems you have absolutely no idea whatsoever about how a typical human being works.
Saying that all people participating in an economy act rationally is the biggest nonsense claim i've ever heared about anything human.
In most cases it is irrational to think you can make a rational choice.
Perhaps you can provide some examples of irrational economic activity?
I'm not talking about investment decisions made by scared people who don't understand the market, which then kills their investments because it performed the way it's supposed to. Laws that are passed are not "economics," either; they are attempts at controlling parts of an economy, passed for either informed or misguided reasons, with specific or unintentional consequences, which can also be deduced if the economy follows its rules.
E.g. raise minimum wage because poor people = higher unemployment due to supply of jobs not being able to afford the price of employees, but also less need for employment, because people who used to work two jobs can now afford to live on one. Rational, or at least purposeful decision, with known outcomes. Only question is the variables involved, which could make the outcome a range of possible but specific options.
Well, there you have your answer!
You said you don't want to talk about these people but you were refering to 'the economy' and these people certainly are part of that.
You seem to have an incredibly narrow view of what constitutes the economy.
So sure, if you just redefine the word to only include people that act rationaly you are right.
But then again you could redefine any word and be right every time! It's so simple!
You cannot say laws are not part of the economy. If they act on it they are part of it.
It's a 'true scotsman' fallacy.
Reality really doesn't care that you want to consider only part of the economy as the only one true economy.
You cannot make a rational decision if you do not know
all the variables.
So in almost any case rationality is an ideal.
And there are various levels of closeness to this ideal.
Hence most people cannot make a rational decision and in fact a lot of the times have no way of knowing how close they are to the ideal with the decision they take.
So rationality is also a relative measure.
A choice can be considered more or less rational given the quality of information it is based on.
Maybe someone rationalized their choices based on the tooth fairy.
Maybe someone bases their choices on what they read in the paper?
Maybe someone bases their choice on what their financial advisers tell them to chose?
Maybe someone wants to take a gamble?
So in reality there is no perfect rationality and economy consists of various relative rationales competing on the world markets.
A perfect example of irrational economic behaviour is anyone buyig on impulse.
These people are not driven by ratio in their choice but by instinct triggered by advertisement (some yummy cakes in a shop window, for instance).
There is also a lot of economic activity simply from greed. People who are too overwhelmed by the posibility of profit to see the chance of winning is almost non existant.
Lotteries would not exist on this scale if people only chose rationally in their economic decision making.