 There are good reasons to think that markets can tell us something about fair prices. A fair price, it seems should reflect how rare something is and how much others would like to have it. There are some goods, such as air or water, that are—at least in high-income countries—in abundant supply. Even though our demand for these goods is high, the supply of these goods is also considerable, meaning that they command relatively low prices on the market. In contrast, goods like a particular child’s primary school artwork may have low supply (perhaps only a few of little Jane’s or Tom’s Turkey-hand-collages exist in the world), but since demand for these goods is limited to the child’s parents, the price these goods would fetch on the market is low. Those goods that are both rare (low in supply) and popular (high in demand), like prime real estate, are expensive. Acquiring them requires giving up a greater amount of those resources we already have. And since there are many others who would like to have these rare goods, it is, intuitively, fair that one should have to give up more to obtain them.