范立安《微观经济学》里一个问题，他讲错了还是我理解错了？

小菜2009 发表于 2010-9-29 00:26
let me try. forgive me for my poor english, because chinese is not available in our library.
Varian claims that the right hand side of the budget constraint in the presence of the tax rebate is taken as fixed.

that is the point.

if we assume that whatever quantity we buy we will receive the tax rate times the quantity, it doesn't work. in that way, the price we face doesn't change, it is also impossible the government will pay us whenever we buy according to whatever quantity we buy.


so i claim that: the government will pay everyone the same amount rebate according to the average quantity.
                        the average consumer is the most special one(we assume it exists, ignoring the integer constraint ), because we can calculate the aggregate demand with it.

and with all the claim from Varian and my extension, the average consumer takes the right hand part as fixed, because he cant affect the average quantity which is decided by all the consumers.

it's intuitively to show (x,y) is not affordable for the average consumer. if we plug (x, y ) in to the left hand side, (p+t)x+y is bigger than m +tx' because x'

谢谢你的回复，我想我明白我的问题出在哪里了。

确实如你所言，tx'是一个固定量。政府所返回的税收是一个平均量，而我们只是返还税收的被动接受者（就像在竞争市场里的价格接受者一样），无论我们的选择如何，得到的税收返还量都是一样的。所以等式右边是固定的。

受到你的启发，我去找了英文版的pdf看了下，范立安确实强调过这个区别的：


可惜中文翻译没有将这种区别和强调表达出来，它将所有的averge consumer都翻译成“普通消费者”，这可能会让读者忽视averge的区别。

是不是可以这样解释，消费者决策的时候，面对的汽油价格为p，税收是t，所以总价格为p+t,对他来说，他并不知道政府补贴和他的消费数量有关，所以他的预算约束是：(p+t)x'+y'=m+补贴 ，其斜率要比原先的预算约束大，所以陡峭，如你教材上的图所示。正如书中所讲，政府想把所有税收补贴返还给消费者，即 补贴=tx'，这是政府预测的税额，而消费者在自己的收入和政府补贴的约束下刚好做出了政府所预测消费数量选择，这有点不合理，范在书里好像也有提到。要理解为什么征税的预算线斜率要比之前的大，关键是要理解，消费者做选择的时候，补贴并不是消费数量x'的函数，补贴是常数。

      如果政府在消费者选择之前，告诉他，好吧，你交的税，我都会还给你的，这是补贴就成了X'的函数，消费者的预算约束和原来一样。