Måste se för nationalekonomistudenterPublicerat: 17 oktober, 2015
I den tredje upplagan av Paul Krugmans och Robin Wells’s lärobok Microeconomics som används för studenter på den första grundkursen i nationalekonomi på Stockholms Universitets påstås detsamma, här är några utvalda citat som visar just det:
The market demand curve is the horizontal sum of the individual demand curves of all consumers in that market. (s.73)
the main reason for studying consumer behavior is to go behind the market demand curve-to explain how the utility-maximizing behavior of individual consumers leads to the downward slope of the market demand curve.(s.282)
So when the price of a good increases, an individual will normally consume less of that good and more of other goods. Correspondingly, when the price of a good decreases, an individual will normally consume more of that good and less of other goods. This explains why the individual demand curve, which relates an individual’s consumption of a good to the price of that good, normally slopes downward-that is, it obeys the law of demand. And since-as we learned in Chapter 3-the market demand curve is the horizontal sum of all the individual demand curves of consumers, it, too, will slope downward.
for the great majority of goods and services, the income effect is not important and has no significant effect on individual consumption. So most market demand curves slope downward solely because of the substitution effect – end of story.