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1. Environmental Economics and Policy

G んわ記 Scarcity 179 mate in order tO create new types Of plants different from parent" cells. One knowledgeable 9See Melvin L. Cotner, NeIson L. BiIIs, and Robert F. BoxIey, op. cit. November 1981 ) : 995 ー 1002. 8See, for example, Lester R. Brown, "World Population Growth, SoiI Erosion, and Food Security," Science 214 ( 27 opment, 1982 ). 7Wor 旧 Bank, ル D 卲 e ん〃襯 e R 0 ノ 982 (Washington, DC: lnternational Bank for Reconstruction and Devel- 6Robert Cooke, "Engineering a New AgricuIture, ”勧れ 0 あ硼 R た 85 (May/June 1982 ) : 24 ー 25. tion process has diminished tO the point that many urban areas are experiencing declining nitude evidenced since 1920 would be accurate. Since the middle of the 1970S , the urbaniza- lt seems unlikely that simple extr 叩 olation of the decline in agriculturalland of the mag- agriculture t0 meet the demand for food. land allowed the smaller amount of land to produce a lot more food. Less land was needed in r 叩 idly raised the value 0f nonagriculturalland. Second, rising productivity of the remaining TWO factors stand out. First, an increasing urbanization and industrialization of society explain the decline Of the relative value Of land in agriculture. agricultural uses is higher. If we are tO explain the historical experience, we must be able to AgricuIturaIIand will be converted t0 nonagriculturalland when its profitability in non- allocation 0f land between agricultural and nonagricultural uses? productivity at historical rates. ls a simple extrapolation reasonable? What determines the ple extrapolation Of this trend would certainly raise questions about our ability to increase the agriculturalland in 1920 had been converted to nonagricultural purposes by 1974. A sim- used for farming. By 1974 the comparable figure was 465 million acres. 9 Some 50 percent of AIIocation of AgricuIturaI Land. During 1920 in the United states, 958 million acres were that satisfies both criteria could involve lower productivity levels. industrialized nations may be neither efficient nor sustainable and a transition to agriculture icy. 8 A close examination Of these reveals that current agricultural practices in the cost Of traditional forms of agriculture, and ( 4 ) the role of price distortions in agricultural pol- 0f land allocated to agricultural use, ( 2 ) the rising cost of energy, ( 3 ) the rising environmental ability of the industrial nations to achieve further productivity gains: ( 1 ) the declining share The outlook is not uniformly bright, however. Four concerns have arisen regarding the cent beyond those achieved with the best previously available seeds and technology. 7 The World Bank has estimated that these techniques could increase yields at least 30 per- synthesis6 4. lncreasing crop yields by improving the way plants use the sun's energy during photo- nitrogen-rich fertilizers by using solar energy tO make ammonia from nitrogen in the air 3. Giving staple food crops such as corn, wheat, and rice the ability to make their own 2. Creating hardy new crop plants capable of surviving in marginal soils 1. Making fOOd crops more resistant to diseases and insect pests niques, including: reviewer in the field suggested several applications for these genetic engineering tech-

2. Environmental Economics and Policy

XX De ″ e Co な 22 Administration 457 Summary 457 Further Reading 459 Additional References 459 Discussion Questions 460 Visions of the Future Revisited ADDRESSING THE ISSUES 461 Conceptualizing the Problem 462 lnstitutional Responses 463 461 EXAMPLE 22.1 PRIVATE INCENTIVES FOR SUSTAINABLE DEVELOPMENT: CAN ADOPTING SUSTAINABLE PRACTICES BE PROFITABLE? 465 Sustai nable Development 467 EXAMPLE 22.2 PUBLIC/PRIVATE PARTNERSHIPS: THE KALUNDBORG EXPERIENCE A Concluding Comment 470 Glossary 473 lndex 483 469

3. The snow leopard

T H E S N 0 W L を 0 PA R D 197 tain practices developed by the markhor 0f Pakistan and the wild goat .(the ancestor 0f the domestic goat, ranging from pakistan tO Greece), bOth Of which take their penises intO their 0 、 mouths, urinate copiously, then spit on their own coats; the beard Of the male goat is an adaptive character, a sort Of urine sponge that perpetuates the fine funky smell for which the goats are known. The itch of the rutting season has begun, and even the young animals play at buttmg and sparrmg, as anxious not tO miss the only lively time in the blue sheep's year. GS wonders at the scarcity 0f the young, concluding that a 50 percent mortality must occur in the first year, due as much tO 、 veakness or disease caused by poor range conditions as tO predation by wolves and leopard. perhaps one Juvenile in three attains maturity, and this may suffice tO sustain the herds, which must adjust numbers tO the limited amount Of habitat that remams snow-free all the year. This region of the Tibetan Plateau is a near desert 0f rock and barren slopes dominated by two thorn shrubs, Ca ga れ 4 and a bush honeysuckle, も 0 れた the blue sheep will eat small amounts 0f almost any growth, including the dry everlasting and the oily juniper, and the adaptations 0f the Caprini for hard, abrasive forage permit limited browsing of this thorny scrub as well. But excepting a few tufts among the thorns, al- most all the native grasses that are its preferred fOOd have been eradicated by the herds 0f yak and sheep and goats that are brought here from distant villages in summer, and the over- grazing has led already t0 erosion.

4. Environmental Economics and Policy

206 劭叩 / 催月 B わ市お 0 〃″ Resources lnstitute, points out, "By an accident of history and geography, half of the third- world external debt and over two-thirds of global deforestation occur in the samefourteerv developing countries. ” ◆ SUSTAINABLE FORESTRY We have examined two types of decisions by landowners—the harvesting decision and the con- version decision—that affect the rate Of deforestation. The first type of decision involves how い、に much timber t0 harvest, hOW 0ften t0 hanves it, and whether tO replant after a harvest. The second type Of decision concerns whether and when tO convert a forest to a different land use. ln bOth cases profit-maximizing decisions may be efficient and these inefficiencies tend t0 create a bias toward higher rates of deforestation. ln these cases correcting these inef- ficiencies can promote bOth efficiency and sustainability. Does the restoration Of efficiency guarantee sustainable outcomes? The answer depends on what is meant by s 加ろん . If the possibility of compensation is entertained along with the "[email protected]•mong.generations" definition, then efficiency is fully compatible with sustainability as long as the economic gains from harvest are invested and shared with future generations. ln this case, even when efficiency results in some deforesta- tion, future generations will not suffer. Let's suppose, however, that we consider sustainable forestry to be realized only when the forests are sufficiently protected that harvests can be realized peröetually. Under this defini- tion, sustainable forestry would occur as long as harvests were limited to the growth of the forest, leaving the volume of wood unaffected over some specified period of time. Efficiency is not necessarily compatible with this definition of sustainable forestry. Maxi- mizing the present value involves an implicit comparison between the increase in value from delaying harvest (largely because of the growth in volume) and the increase in value from har- vesting the timber and investing the earnings (largely a function of ろ the interest rate earned on invested savings). With slow-growing species, the growth rate in volume is small; maximizing the present value may well involve harvest volumes higher than the net growth of the forest. The search for sustainable forestry practices that are also economically sustainable has led tO the development of r 叩 idlygrowing tree species and plantation forestry. R 叩 idly grow- ing species raise the attractiveness Of replanting, because the invested funds are tied up for a shorter period Of time. These species are raised in plantations, where they can be harvested and replanted at a IOW cost. Forest plantations have been established for such varied purposes as supplying fuelwood in developing countries to supplying pulp for p 叩 er mills in both the industrialized and developing countries. PIantation forestry is controversial. Not only do plantation forests typically involve a sin- gle species 0f tree, which results in a poor wildlife habitat, they also require large inputs of fertilizer and pesticides. ln some parts Of the world the natural resilience of the forest ecosystem is sufficiently high that sustainability is ultimately achieved, despite decades of unsustainable levels of har- vest. ln the United States, for example, sometime during the 1940S the net growth of the nation's timberlands exceeded timber removals. The four surveys conducted since that time confirm that net growth has exceeded harvests, in spite of a rather large and growing demand for timber. The total volume of forest in the United states has been growing since at least ヾ

5. Environmental Economics and Policy

210 劭叩 r 〃召わ市″彑秀 Fo 立〃″ Most of these changes could be implemented by individual nations tO protect their own forests, and tO dO SO would be in their interests. By definition, inefficient practices cost more than the benefits received. The move tO a more efficient set Of policies would necessarily gen- erate more net benefits, which could be shared in ways that build political support for the change. But what about the global inefficiencies? HOW can those be resolved? Severalæconomic strategies-exist. They share the characteristic Of involving the compen- sation Of the nations that confer external benefits SO as tO encourage conservation actions consistent with glObal efficiencye Debt-Nature Swaps. One strategy involves reducing. thep on the forests caused by the international debt owed by many developing ℃ ountries. Private banks h01d most 0f the e t, and ・ typically motivated by a desire tO protect biodiversity. Nonetheless, it is possible tO find some common ground for negotiating strategies tO reduce the debt. Banks realize that complete repayment Of the loans is probably not possible. Rather than completely write Off the loans, an action that not only causes harm tO the income statement but alSO creates adverse incentives for repayment Of future loans, they are willing tO consider alternative strategies. ()ne Of the most innovative policies that explores common ground in international arrangements has become known as the イわれーレ re 〃 . lt iS innovative in tWO senses: ( 1 ) the uniqueness of the policyinstrument and ( 2 ) e rect involvement of nongovern- mental organizations in implementingthe policy. A debt-nature swap involves the purchase ()t a discounted value in the secondary debt market) Of a developing-country debt, usually by a non-governmental environmental organization (NGO). The new holder 0f the debt, the NGO, offers to cancel the debt in return for an environmentally related action on the part of the debtor nation. ln JuIy 1987 , for example, a U. S. environmental organization purchased $ 650 , 000 worth of Bolivia's foreign debt from a private bank at a discounted price of $ 100 , 000. lt then swapped the face value of the debt with the government of Bolivia in return for an agreement tO put together a public-private partnership. This partnership would develop a program that combines ecosystem conservation and regional development planning in 3.7 million acres of designated tr 叩 ical forestland. The agreement also includes a $ 250 , 000 fund in local currency for establishing and administering a system for protecting the forest reserve. Other arrangements involving different governments and different environmental organi- zations have since followed this lead. The main advantage of these arrangements to the debtor nation is that a significant foreign exchange obligation can be paid 0 with domestic currency. Debt-nature sw 叩 s offer a realistic possibility of turning what has been a major force for unsus- tainable economic activity (the debt criSiS) intO a force for resource conservation. Extractive Reserves. One strategy designed to protect the indigenous people of the forest as well as tO prevent deforestation involves the establishment of e. ズ〃 uc ″ se 耀 . These areas would be reservedforthe indigenous people to engage in their traditional hunting andgath— e ri ng activi ties. ーー Extractive reserves have already been established in the Acre region of Brazil. Acre's main activity comes from the thousands of indigenous men who tap the rubber trees scattered

6. Environmental Economics and Policy

E 市巨 enc. 彑 and CO - E け加 ene 351 control could well be justified. Because in many cases nonpoint-source pollutants are not the same as point-source pollutants, this is a logical possibility. Or, second, if the costs Of control- ling nonpoint sources even tO a small degree are very high, this could justify benign neglect as well. Are either Of these conditions met in practice? COStS. Because research iS in itS infancy, COSt information iS scarce. ()f the small amount Of literature available, one study can give us a sense Of the economic analysis. Palmini conducted an analysis Of the potential effects Of agricultural nonpoint policies on two small rural coun- ties in lllinois. 14 The specific policies he examined were designed to control nitrogen (which can cause eutrophication), sediment (soil erosion), and pesticides. His model relates these policies tO the chOice Of various farming practices, the effects Of these choices on costs, and the financial return tO farmers after covering variable COStS. His results indicated that a rather dramatic reduction ( 74 percent) in soil erosion could be achieved at a cost Of less than 1 percent Of the earnings after variable costs were covered. A ban on selected pesticides was predicted t0 cause a switch tO other, less damaging pesticides, which would reduce the return tO farmers by 0.7 percent. The maJOr estimated economic impact came from policies designed tO reduce nitrogen use. Palmini considered the effects Of quantity restrictions (ceilings on amount used per acre) and the impact Of taxes on nitrogen use. Quantity restrictions necessary tO reduce pollution alSO substan- tially reduced revenues and projections. Because the demand for nitrogen is price inelastic, if nitrogen taxes were used, very high rates would be needed tO reduce nitrogen use very much. The extra expense Of nitrogen control would represent a large financial burden on farmers, which they could only pass on in higher prices if all farmers were subjected tO similar controls. This would make unilateral state control difficult, because it would place the farmers in that state in jeopardy. This study suggests that some nonpoint control can probably be reasonably under- taken, because the costs seem IOW. However, it also suggests that the conclusion that a11 nonpoint sources can be cheaply controlled iS not correct. AS in Other areas Of environmen- tal policy, the form and intensity Of government intervention would have tO be tailored tO the specific problem. The fact that point and nonpoint sources have received such different treatment from the EPA suggests the possibility that costs could be lowered by a more careful balancing 0f these control options. One study Of phosphorus control in the Dillon Reservoir in C010rad0 by lndustrial Economics, lnc. , supports the validity Of this suspicion. 15 ln this reservoir, four municipalities constitute the only point sources Of phosphorus, whereas there are numerous uncontrolled nonpoint sources in the area. The combined phOS- phorus load on the reservoir from point and nonpoint sources is projected tO exceed its assim- ilative capacity. The traditional way tO reduce the projected phosphorus load would be tO impose even more stringent controls on the POint sources. The study found, however, that bY following a 14Dennis J. PaImini, "The Secondary lmpact Of Nonpoint P011ution Controls: A Linear Programming—lnput/Output Analysis," JO ″記砿 E れⅵれ例ね I 刃 co れ 0 襯 ~ れイ M れ ge 襯例ー 9 (September 1982 ) : 263 ー 78. 151ndustrial Economics, Case S ル市 0 れ the Tra 市れ 0fEff7uent 切ホ : D ″んれ e 川 0 耘 Final R 印 0 (Cambridge' 犱 : lndustrial Economics, 1984 ).

7. Environmental Economics and Policy

eEco れ om た p 〃 ro ロ c んね Po 〃″″ 0 Co れ″ 0 / 1 1 1 AII of this provides a menu of 叩 portunities for population control. The reasons listed here represent potent forces for change, yet these methods should be used with care. lnduc- ing a family tO have fewer children without assisting the family in satisfying the basic needs the children were fulfilling (such as old-age security) would be inequitable. Policies in China illustrate just how far economic incentives can be carried. On the basis Of announced regulations, one-child parents receive subsidized health expenditures; priority in education, health care, and housing; and additional subsidized food. MeanwhiIe, parents whO have more than two children receive a reduction of 5 percent in their total income for the third child, 6 percent for the fourth, and so on. Also, families are denied access tO further subsidized grain beyond that which they already receive for their two pre- vious children. lnitially these policies did bring about a rather dramatic fall in the birthrate in China. China's fertility rate had dr 叩 ped from 5.97 in 1968 to 1.8 in 1995. However, the policies are SO draconian as tO have precipitated a degree of resistance sufficient to undermine the effort. Countries seeking tO reduce fertility do not have to resort to extreme measures. policies such as enhancing the status Of women, providing alternative sources of old-age security, and supplying employment opportunities that equalize income distribution are both humane and effective. And it is important to note that these policies can make headway even in very 10W income areas (ExampIe 6.3 ). Vernon Ruttan has summarized some of the studies that have evaluated the effects of this type 0f approach: ( 1 ) Greater family wealth sustains higher education levels and better health; ( 2 ) a rise in the value Of the mother's time has a positive effect on the demand for contracep- tive services and a negative effect on fertility; ( 3 ) a rise in the value of the father's earnings has a positive effect on completed family size, child health, and child education; and ( 4 ) increases in mother's schooling has a negative effect on fertility and infant mortality and a positive effect on nurturing and children's schooling. 13 One way tO empower women is tO increase their income-earning potential. The typical way tO increase income-earning potential is through investment in either human c 叩 ital (). g. , education and training) or physical capital (). g. , looms and agricultural equipment). Funds for investment are normally obtained from banks. ln order to minimize their risk, banks usu- ally require co ″記 (). e. , property that can be sold to cover the proceeds of the loan in a case Of failure tO repay). ln many developing countries, women are not allowed to own property, so they have no collateral. As a result traditional credit facilities are closed to them and good investment opportunities are forgone. One innovative solution to this problem was developed by the Grameen Bank in Bangladesh. 14 This bank uses peer pressure rather than collateral requirements to lower the risk Of nonpayment. Smallloans are made to individual women who belong to a group of five or SO members. Upon complete repayment 0f all individualloans within the group, the members 13Vernon W. Ruttan, "Perspectives on P 叩 ulation and Development," d Jo ″ m 記砿 c 記 ra / Eco れ 0 襯た s 39 , No. 4 (October/December 1984 ) : 636. Ruttan in turn credits Robert E. Evenson, "Notes on the New Home Econom- ics," in Home ECO れ 0 襯沁イ 0 c ル加 T んⅣ CO ″れ s. , Miriam Seltzer, ed. (St. Paul, MN: University 0f Minnesota College 0f Home Economics Center for Youth Development and Research, 1980 ). 14Abu N. Wahid, ed. , 励 2 Grameen 召れん・ P 催 Re ″加 Ba れグ (BouIder, CO: Westview Press, 1993 ).

8. The Mayflower Miracle: The Pilgrims' Own Story of the Founding of America

28 February CO 〃 m, 0m0 drawing 可 0 れ ーれ市 0 ル dancer, labelled 'The 〃ド . 98 behind them. When they returned they discovered their tools had been taken away, SO in future they decided tO be more on their guard and to keep their guns always ready t0 fire. With more PiIgrims dying and the survivors getting we aker and weaker, fear began tO spread through the settlement now that the lndians seemed so close. Some 0f the Pilgrims were getting so fnghtened that they wanted tO go back t0 the ー佖″ 0 and so, after a meetmg with the leaders, it was decided tO form a proper guard responsible for protecting the colony. WinsIow said that ⅲ the morning, they called a meeting tO establish 'military orders' among themselves. They selected MyIes Standish their Captain and gave him authority of command ⅲ such affairs. Having served ⅲ the English military forces, Standish was well versed ⅲ traditional m ⅲね practices and procedures. As time passed he taught his fellow Pilgrims the basic arts 0f handling weapons and forming defensive positions m case Of enemy attack. lt was Bradford's opinion that, havmg made a good start on building the settlement, this was the next important milestone in the settle- ment's history: 'And after they had provided a place for their goods, or comone store , (which were long in unlading for want of bo ats, foul- ness Of winter weather, and sicknes) and begun some small cottages for their habitation, time would admitte, they mette and consulted of lawes & orders, b0th for their civill & military Governmente, the necessitie Of their condition did require, still adding therunto urgent occasion in severall times, and a.S cases did . Now if the lndians did attack they would be prepared. With all the setbacks to the building program, the delays in establish- ing the settlement and the continual threat Of lndian attack, factions inevitably formed. Many Of them, seeing their brothers and sisters dying around them, were terrified that they might be the next tO die. Bradford wrote: 'ln these hard & diffcult beginings they found some discontents & murmurings arise amongst some, and mutinous speeches & carriags ⅲ other; but they were soone quelled & overc ome by the wisdome , patience, and just & equal carrage Of things by the Govenor and better part, which clave faithfully togeather in the mame. The continuing death toll was nevertheless alarming. By the end of February the death toll had reached a peak. With many two or three people dying a day it was not long before half 0f their original number lay dead and buried beneath the frozen ground. Bradford: 'But that which was most sadd & lamentable was, that ⅲ 2 or 3 moneths time, halfe Of their company dyed, espetially ⅲ January & February, being the depth 0f winter, and wanting houses & other comforts; being infected with the scurvie & other diseases, which this long vioage & their inacomodate condition had brought upon them; SO ther dyed some times 2 or 3 0f a day, ⅲ the foresaid time; that 0f 100 & Odd persons, scarce 50 remained'.

9. 50 Great Short Stories

28 D 0 R 0 T H Y PA R K E R gether every Ⅱ 00n , together they set out for home at the end Of the day's WO ⅸ . Many of their evenings and most of their Sun- days were passed ⅲ each other's company. Often they were jOined by tWO young men, but there was no steadiness tO any such quartet; the two young men would give place, unlamented, t0 two other young men, and lament would have been inappro- priate, really, since the newcomers were scarcely distinguish- able 仕 om their predecessors. lnvariably the girls spent the fine idle hours of their hot-weather Saturday afternoons together. Constant use had not worn ragged the fabric oftheir friendship. They looked alike, though the resemblance did not lie ⅲ their features. lt was in the shape of their bodies, their move- ments, their style, and their adornments. Annabel and Midge did, and completely, all that young offce workers are besought not to do. They painted their lips and their nails, they darkened their lashes and lightened their hair, and scent seemed to shim- mer om them. They wore thin, bnght dresses, tight over their breasts and high on their legs, and tilted slippers, fancifully strapped. They 100ked conspicuous and che 叩 and charming. NOW, as they walked across to Fifth Avenue with their skirts swirled by the hot wind, they received audible admiration. Young men grouped lethargically about newsstands awarded them murmurs, exclamations, even—the ultimate tribute— whistles. Annabel and Midge passed without the condescen- sion ofhurrying their pace; they held their heads higher and set their feet with exquisite-precislon, as if they stepped over the necks ofpeasants. Always the girls went t0 walk on Fifth Avenue on their free afternoons, for it was the ideal ground for their favorite game. The game could be played anywhere, and indeed, was, but the great shop windows stimulated the two players t0 their best form. Annabel had invented the game; or rather she had evolved it 丘 om an 01d one. Basically, it was no more than the ancient sport ofwhat-would-you-do-if-you-had-a-million-dollars? But Annabel had drawn a new set 0f rules for it, had narrowed it, pointed it, made it stricter. Like all games, it was the more ab- sorbing for being more diffcult.

10. Environmental Economics and Policy

44 劭叩 r 3 ん加 0 2 E れれ m 例た 2 肱 0 Benefit-cost analysis grapples with the evaluation 0f risk in several ways. SUPPOS% for exam- ple, that have a range 0f policy 叩 tions ん B, C, D and a range 0f possible outcomes G for each Of these policies depending on hOW the economy evolves over the future. These outcomes for example, might depend on whether the demand growth for the resource is 10W , medium or high. Thus, if we choose policy we might end up with outcomes AE, , 姻 , or G. Each 0f the Other policies has three possible outcomes as well, yielding a tOtal Of 12 possible outcomes. We could conduct a separate benefit-cost analysis for each Of the 12 possible outcomes. UnfortunateIy, the policy which maximizes net benefits for E may be different from that which maximizes net benefits for F or G. Thus, if we only knew which outcome would prevail' we could select the policy that maximized net benefits; the problem is that we don't. Furthermore' choosing the POlicy which is best if outcome E prevails may be disastrous if G results instead. When a dominant policy emerges, this problem is avoided. A 襯加ー〃 0 ″ c. is one that confers higher net benefits for every outcome. ln this case, the existence Of risk concerning the future is not relevant for the policy chOice. Though this fortuitous circumstance is excep- tional rather than common, it can occur. Other options exist even when dominant solutions dO not emerge. SUPPOSe, for exampl% that we were able tO assess the likelihood that each Of the three possible outcomes would occur. Thus we might expect outcome E t0 occur with probability 0.5 , with probability 0.3 , and G with probability 0.2. Armed with this information, we can estimate the expected present value Of net benefits. The e, ズ〃 ec 〃れ一ん e 砿れ可ろ例 e 〃な for a particular POlicy is defined as the sum over outcomes Of the present value Of net benefits for that POlicy where each outcome is weighted by its probability Of occurrence. SymbolicallY this is expressed as: = number Of outcomes being considered J = number Of policies being considered = present value Of net benefits for policyj if outcome / prevails 名 = probability 0f the ith outcome occurring EP し公召ノ = expected present value of net benefits for policyj E ハ召ー PiPVNBlJ , P 惞召 ~ where at least some members Of SOCiety are riSk lovers while the existence Of insurance suggests ls that a valid assumption? The evidence is mixed. The existence of gambling suggests that that society is risk-neutral. r なん辺リ e e behavior. Using the expected present value Of net benefits approach implies be exhibiting ん I ⅲ 0 behavior, while a preference for the definite $ 50 would suggest indifferent between these tWO choices. If you view the lottery as more attractive, you would lottery is $ 50 = 0.5 ( $ 100 ) + 0.5 ( $ 0 ). ) You would be said to be risk-neutral if you would be $ 100 and a 50 percent chance of winning nothing. (N0tice that the expected value of this given a definite $ 50 or entering a lottery in which you had a 50 percent chance Of winning most easily by the use Of an example. SUPPOSe you were allowed tO choose between being risk. This approach is appropriate if society is risk-neutral. R なんれ e ケ記″彑 can be defined more heavily. lt also, however, makes a specific assumption about society's preference for This approach has the substantial virtue that it weighs higher probability outcomes The final step is to select the policy with the highest expected present value Of net benefits.