I don't assume he or she produces nothing, I make the correct assumption, that as capital per worker falls, in aggregate, output per worker falls, thus income per worker falls. We are talking large numbers, not one or two people, I'm thinking in terms of millions, but still, even a few people make some difference at the margin. Do you reallly think 10 million people could move to the US and not have an impact, a negative impact on the economy? What about 300 million? What about 1 billion? If we had an open door policy, it COULD happen (in theory at least)!!! Do you think we would not be affected? Well, its like they always say, if it doesn't make sense with small numbers, use large ones, and soon the theory will make some sense!!!
Actually, the truth is, its the capital stock of a country / population is the issue. Sorry, I won't simplify things again. But I won't explain the whole model simply to state something either. Yes, income per capita MUST FALL, and yes, by most definitions it makes the US a poorer nation. We tend to define rich and poor nations by GDP per capita. Sorry, I didn't invent or choose the means with which we measure it.
So is china richer than Switzerland because it has more Gross Domestic Product? Are Chinese better off than Swiss? I hope you are seeing my point about now!!!
You are obviously arguing a different point though, that the person from abroad is made better off. I don't argue that!!! What it does do, is that it lowers growth of the economy, and thus makes the ECONOMY as a whole less wealthy (on a per capita basis of course). And for the lefties, that means less to redistribute now, and in the future!!!
Furthermore, you are assuming that there is no unemployment, and that one person finding a job doesn' displace another. There is a natural level of unemployment remember. Full employment doesn't exist!!! And increasing the number of low skilled people in an economy that has an excess of low-skilled workers already, and a shortage of high-skilled workers is going to increase unemployment, and probably the natural rate of unemployment as well (ok maybe we aren't short ANY workers right NOW, low-skilled or high-skilled, and that presents further problems, doesn't it). Well, higher unemployment probably means more resdistribution, and more redistribution means less is available for capital investment, and thus, depending on where the level of savings is, the capital stock of the nation will grow more slowly or decline, leaving EVERYONE worse off (in a macro sense of course)!!! Clearly, now you have not only the population side of things changing, but also capital investment is falling. So capital per workier = k/p is even smaller in the long-run than just the inital shock of chaning P would have been.
At the same time, if we only take the best and brightest from abroad, we are also hurting those economies from which they came. Clearly they could benefit from having more human capital at home!!! On the other hand, if nations send us their least educated, they are helping themselves, because now they have more capital per worker, and also more human capital per worker (human capital is an issue as well, but only if you have enough physical capital for these workers to take advantage of).
Ok, I don't want to argue this topic. If you don't like the "theory" feel free to research the "Solow Growth Model" on your own (google should turn up some good links for ya, I'm sure someone else can explain better than me, maybe Robert Solow himself), it will give you the basic idea (he won the nobel prize for this model and his research in this field). You can find newer models, but they are much more complex, and of course, aren't Nobel prize winning models.
Luis G,
I wasn't refering to Mexico in particular, if you will notice. If you look more closely, and if you were to make ANY assumption about what country I was refering to, it should have rather been INDIA. But I was speaking in general terms just to clarify!!!
