The reason why cheap food hurts farmers is simple. Farmers with low education and no understanding of economics will also explain: because there is too much food, it can't be sold at a price. A year with more food is equivalent to a year with less food, but the investment is much larger and uneconomical. Such a simple truth has become mysterious in economics, which belongs to the undergraduate level. The following excerpt from "Western Economics" (Gao Hongye, Renmin University of China Press, p57) is devoted to the issue of "cheap grain hurts farmers": "cheap grain hurts farmers, which is a long-standing saying of China. It describes such an economic phenomenon: in a bumper harvest year, farmers' income actually decreased. This seemingly incomprehensible phenomenon can be explained by the principle of elasticity. The fundamental reason for this phenomenon lies in the fact that agricultural products are often commodities lacking demand price elasticity, as shown in Figure 2-24. The demand curve d of agricultural products in the figure is inelastic. The bumper harvest of agricultural products moves the supply curve from the position of S to the right position of S'. Under the action of inelastic demand curve, the equilibrium price of agricultural products has greatly decreased from P 1 to P2. Because the decline in the balanced price of agricultural products is greater than the increase in the balanced quantity of agricultural products, the total income of farmers will eventually decrease. The reduction of total income is equivalent to the difference between the areas of rectangles OP 1E 1Q 1 and OP2E2Q2 in the figure. Pictured: Similarly, in the poor harvest year, due to the inflexibility of the demand curve, the decline in the equilibrium price of agricultural products will be less than the increase in the equilibrium price caused by it, and finally the total income of farmers will increase. Let's make an evaluation of this paragraph: the fact described is that "cheap grain hurts farmers" and its premise is "bumper harvest". If it is not a bumper harvest year, cheap food will also hurt farmers, but everyone thinks it is normal. So harvest is the specific premise of this topic. From the perspective of supply and demand theory, what does a bumper harvest mean? Obviously, "supply" should have increased. But to our surprise, farmers are food suppliers. Why is the problem caused by the increase of supply not explained by the price elasticity of supply, but by the price elasticity of demand? At the same time, there is no information about how the demand changes from "cheap grain hurts farmers" and "good harvest". If you use the demand curve, you must add other conditions, but this is no longer the meaning of the topic. This is one of them. Secondly, it is strange to say that "the bumper harvest of agricultural products moves the supply curve from the position of S to the position of S". According to the description in front of the textbook, the movement of demand line is the change of demand caused by the change of other factors under the condition of constant price, and this other factor does not include supply, so it is silent; The translation of the supply line is caused by the change of supply under the condition of constant demand. From the written expression alone, there is an obvious lack of symmetry, and telling the truth is nonsense. Why is the translation of demand line not caused by the change of demand under the condition of constant supply? Why is the translation of the supply line not caused by other factors when the price remains unchanged? Harvest means an increase in supply. Why is the change of supply not the movement of a point on a supply line, but the translation of the supply line? If the supply change will cause the supply line to translate, what is the supply line for? When is it a point moving on a straight line? If the change of supply will lead to the translation of the supply line under the condition of constant demand, but the supply line will not move under the condition of constant demand and supply, then we have to ask: what changes does the supply line reflect? Isn't there only one price factor left under the condition of constant supply and demand? What curve can a factor talk about? Some people may say: you don't understand the difference between demand change and demand change, supply change and supply change. Not exactly. This is an academic conspiracy. Above the confusing concept, we should change the name of the change of supply and demand, such as "the movement of demand line" and "the movement of supply line" For the three variables Qs, Qd and P, it is easy to discuss their relationship with line and plane motion by using three-dimensional graphics, and it is not necessary to pay attention to the artificial concept distinction. This circuitous logic of "the change of a is not the change of the quantity of a" is just to find convenience for nonsense. According to this logic, we can create more so-called "knowledge": the change of labor is not the change of labor quantity, the change of value is not the increase or decrease of value, the change of price is not the change of price value, and the change of height is not equal to the change of height ... It is very difficult to graduate with a doctorate! Thirdly, the article says that "the demand curve D of agricultural products in the figure is inelastic", that is to say, the curve D is inelastic. But we can prove that any linear demand curve has three kinds of elasticity at the same time. The proof is as follows: the price elasticity of demand is e =-(dq/DP) × p/q. If we substitute the demand function Qd=α-βP, we can get e = α/qd- 1, e = 1, that is, α/qd- 1. Similarly, when E > 1, P > α/2β is elastic, while when E < 1, P < α/2β is inelastic. Graphically, this shows that the elasticity of Qd is 1 at half of the interval (0, α), elastic to the left and inelastic to the right. However, according to the definition of price elasticity, any straight demand curve must have three kinds of price elasticity at the same time. (In fact, in the textbook, Figure 2- 13A on page p42 has given this three-segment diagram, but I don't know why several different elastic lines are listed in the previous explanation. You know, there is no demand line with only one flexibility. ) Then, looking back at the above discussion, how do we know that the positions of the two equilibrium points, E 1 and E2, are in inelastic sections? From the diagram, just passing through the unit elasticity point can only show that the author does not have the concept of "any demand line is three kinds of elasticity" in his mind. How to produce a product, if you can draw a demand curve, you must have three kinds of flexibility at the same time. It is unreasonable and nonsense to say that agricultural products are often commodities lacking demand and price elasticity. Fourth, if the grain harvest must be cheap, it is obviously based on the opposite of "things are rare", that is, "things are obscene." The mathematical expression of "things are obscene" is precisely that the supply line has a negative slope, not a positive slope, and its shape should be the same as that of the demand line to describe "supply increases and prices fall", which is contrary to the supply law. On this issue, my view is that things are rare and things are obscene, both of which are right, while the contradictory law of supply is wrong, and the wrong reason is the result. But there are always people who think that it can be causal, or that supply and demand and prices can be mutually causal. Then explain the root of this problem. Maybe we can overturn the saying that "things are rare"? I call these five words the first law of economics. Fifthly, as for the statement that "in the poor harvest year, due to the inflexibility of the demand curve, the decrease of the equilibrium price of agricultural products will be less than the increase of the equilibrium price caused by it, which will eventually lead to the increase of farmers' total income", it is even more difficult to agree. I grew up in the countryside, knowing that farmers want a bumper harvest, but there is no hope of a poor harvest. Professor Gao should explain this to the State Council: Is it necessary to increase farmers' income by reducing grain production? Whether the country wants to increase farmers' income on the one hand and grain output on the other is a wishful contradiction, or it is contrary to the laws of economics. In fact, the "base" of hurting farmers is not the general price reduction, but the level below the cost. Price fluctuation is normal. If it is higher than the cost, there will be a profit. As long as there is profit, the greater the output, the better. This is why farmers always hope for a bumper harvest. If cheap means that the price is lower than the cost, then the truth that "cheap grain hurts farmers" applies not only to "grain", but to all products. In reality, it is mostly because the government forcibly buys grain at a low price, which causes policy harm to farmers, and there is not much economic reason to talk about.

Satisfied, please adopt.