Economics(concept of methodolgy)

n.a.

2007-10-09 7:27 am

1.The sentence below comes from a book:
" Whenever the postulates and assumptions are true, the conclusion or hypothesis should be true. On the other hand, when the conclusion or hypothesis is false, some of the postulates or assumptions must be false."
Please comment the above sentence.(With the example is better)
I think that if the postulates and assumption are true, the hypothesis may not be confirmed as the hypothesis may not be logical consistent or have generalization power.

更新1:

Then, I want to confirm the idea that I have. 2. Do we consider constained maximization is a tautology?In fact, if one day the people don't maximize their interests, then the the maximization is not always true.

更新2:

If your answer to question is yes, then is it useful to make any predictions under this postulates?If no, then briefly explain your answer.(With the example is better)Thanks!

回答 (1)

garlic2010

2007-10-09 2:31 pm

✔ 最佳答案

Use the simple logic
All men will die.
John is a man.
John will die.
(P -> Q)

If the premise (All men will die) is true, then the conclusion must be true because the conclusion is already contained in the premise.

If John does not die, either All men will die, or John is a man should be refuted.
(~Q -> ~P)
But just becuase someone dies you cannot infer that the person is a man.
(Q does not imply P)
Even when it is found out that John is a fairy, not man, we cannot conclude that John will not die.
(~P does not imply ~Q)

Key to 2 is that economics is a positive, not normative discipline. It does not matter whether people maximize, people are always found to be behaving in a certain pattern. Economics look at what people are doing, not what they should be doing. If people always buy more at lower price, we have a law of demand. It does need the postulate of constrained maximization. Maximization tries to explain why people behave the way they do. The why can be wrong but it does not change people's behaviour.

Constrained maximization is a tautology because it is just a term we use to call people's behaviour. You can call it something else, say immuization, and it does not change a thing.

👍 0 👎 0