## Positive Externalities and Public Goods

Figure 1. View from Voyager I Launched by NASA on September 5, 1977, Voyager 1’s primary mission was to provide detailed images of Jupiter, Saturn, and their moons. It took this photograph of Jupiter on its journey. In August of 2012, Voyager I entered interstellar space—the first human-made object to do so—and it is expected to send data and images back to earth until 2025. Such a technological feat has a lot to do with economic principles. (Credit: modification of work by NASA/JPL)

### The Benefits of Voyager I Live On

The rapid growth of technology has increased our ability to access and process data, to navigate through a busy city, and to communicate with friends on the other side of the globe. The research and development efforts of citizens, scientists, firms, universities, and governments have truly revolutionized the modern economy. To get a sense of how far we have come in a short period of time, let’s compare one of humankind’s greatest achievements to the smartphone most of us have in our coat pocket.

In 1977 the United States launched Voyager I, a spacecraft originally intended to reach Jupiter and Saturn, to send back photographs and other cosmic measurements. Voyager I, however, kept going, and going—past Jupiter and Saturn—right out of our solar system. At the time of its launch, Voyager had some of the most sophisticated computing processing power NASA could engineer (8,000 instructions per second), but by the time it left the solar system (in 2012, actually) we Earthlings were using handheld devices that could process 14 billion instructions per second.

Still, the technology of today is a spillover product of the incredible feats accomplished by NASA thirty years ago. NASA research, for instance, is responsible for the kidney dialysis and mammogram machines that we use today. Research in new technologies not only produces private benefits to the investing firm, or in this case to NASA, but it also creates benefits for the broader society. In this way, new knowledge often becomes what economists refer to as a public good. This leads us to the topic of this chapter—technology, positive externalities, public goods, and the role of government in the encouragement of innovation and the social benefits that it provides.

## Introduction to Positive Externalities and Public Goods

Can you imagine a world in which you did not own a cellular phone or use Wikipedia? New technology changes how people live and work and what they buy. Technology includes the invention of new products, new ways of producing goods and services, and even new ways of managing a company more efficiently. Research and development of technology is the difference between horses and automobiles, between candles and electric lights, between fetching water in buckets and indoor plumbing, and between infection and good health from antibiotics.

In December 2009, ABC News compiled a list of some of the technological breakthroughs that have revolutionized consumer products in the past 10 years:

• GPS tracking devices, originally developed by the defense department and available to consumers in 2000, give users up-to-date information on location and time through satellite technology.
• In 2000, Toyota introduced the Prius hybrid car, which greatly improved fuel efficiency.
• Also in 2000, AT&T offered its customers the ability to text on a mobile phone.
• In 2001, Wikipedia launched a user-generated encyclopedia on the Web.
• Even though Napster died in 2001, the company launched music downloading and file sharing, which revolutionized how consumers get their music and videos.
• In 2003, the Human Genome project was completed. It helps to fight disease and launch new pharmaceutical innovations.
• Also in 2003, the search engine became a way of life for obtaining information quickly. The search engine companies also became innovators in the digital software that dominates mobile devices.
• In 2006, Nintendo launched Wii and changed the way video games are played. Players can now be drawn into the action and use their bodies to respond rather than a handheld device.
• Apple introduced the iPhone in 2007 and launched an entire smartphone industry.

With all new technologies, however, there are new challenges. This chapter deals with some of these issues: Will private companies be willing to invest in new technology? In what ways does new technology have positive externalities? What motivates inventors? Does government have a role to play in encouraging research and technology? Are there certain types of goods that markets fail to provide efficiently, and that only government can produce? What happens when consumption or production of a product creates positive externalities? Why is it unsurprising when a common resource, like marine fisheries, is overused?

## Why the Private Sector Under Invests in Innovation

Market competition can provide an incentive for discovering new technology because a firm can earn higher profits by finding a way to produce products more cheaply or to create products with characteristics consumers want. As Gregory Lee, CEO of Samsung said, “Relentless pursuit of new innovation is the key principle of our business and enables consumers to discover a world of possibilities with technology.” An innovative firm knows that it will usually have a temporary edge over its competitors and thus an ability to earn above-normal profits before competitors can catch up.

In certain cases, however, competition can discourage new technology, especially when other firms can quickly copy a new idea. Consider a pharmaceutical firm deciding to develop a new drug. On average, it can cost $800 million and take more than a decade to discover a new drug, perform the necessary safety tests, and bring the drug to market. If the research and development (R&D) effort fails—and every R&D project has some chance of failure—then the firm will suffer losses and could even be driven out of business. If the project succeeds, then the firm’s competitors may figure out ways of adapting and copying the underlying idea, but without having to pay the costs themselves. As a result, the innovative company will bear the much higher costs of the R&D and will enjoy at best only a small, temporary advantage over the competition. Many inventors over the years have discovered that their inventions brought them less profit than they might have reasonably expected. • Eli Whitney (1765–1825) invented the cotton gin, but then southern cotton planters built their own seed-separating devices with a few minor changes in Whitney’s design. When Whitney sued, he found that the courts in southern states would not uphold his patent rights. • Thomas Edison (1847–1931) still holds the record for most patents granted to an individual. His first invention was an automatic vote counter, and despite the social benefits, he could not find a government that wanted to buy it. • Gordon Gould came up with the idea behind the laser in 1957. He put off applying for a patent and, by the time he did apply, other scientists had laser inventions of their own. A lengthy legal battle resulted, in which Gould spent$100,000 on lawyers, before he eventually received a patent for the laser in 1977. Compared to the enormous social benefits of the laser, Gould received relatively little financial reward.

A variety of studies by economists have found that the original inventor receives one-third to one-half of the total economic benefits from innovations, while other businesses and new product users receive the rest.

### The Positive Externalities of New Technology

Will private firms in a market economy under invest in research and technology? If a firm builds a factory or buys a piece of equipment, the firm receives all the economic benefits that result from the investments. However, when a firm invests in new technology, the private benefits, or profits, that the firm receives are only a portion of the overall social benefits. The social benefits of an innovation take into account the value of all the positive externalities of the new idea or product, whether enjoyed by other companies or society as a whole, as well as the private benefits received by the firm that developed the new technology. Positive externalities are beneficial spillovers to a third party, or parties.

Consider the example of the Big Drug Company, which is planning its R&D budget for the next year. Economists and scientists working for Big Drug have compiled a list of potential research and development projects and estimated rates of return. (The rate of return is the estimated payoff from the project.) Figure 2 shows how the calculations work. The downward-sloping DPrivate curve represents the firm’s demand for financial capital and reflects the company’s willingness to borrow to finance research and development projects at various interest rates. Suppose that this firm’s investment in research and development creates a spillover benefit to other firms and households. After all, new innovations often spark other creative endeavors that society also values. If we add the spillover benefits society enjoys to the firm’s private demand for financial capital, we can draw DSocial that lies above DPrivate.

If there was a way for the firm to fully monopolize those social benefits by somehow making them unavailable to the rest of us, the firm’s private demand curve would be the same as society’s demand curve. According to Figure 2 and Table 1, if the going rate of interest on borrowing is 8%, and the company can receive the private benefits of innovation only, then the company would finance $30 million. Society, at the same rate of 8%, would find it optimal to have$52 million of borrowing. Unless there is a way for the company to fully enjoy the total benefits, then it will borrow less than the socially optimal level of $52 million. Figure 2. Positive Externalities and Technology Big Drug faces a cost of borrowing of 8%. If the firm receives only the private benefits of investing in R&D, then its demand curve for financial capital is shown by DPrivate, and the equilibrium will occur at$30 million. Because there are spillover benefits, society would find it optimal to have $52 million of investment. If the firm could keep the social benefits of its investment for itself, its demand curve for financial capital would be DSocial and it would be willing to borrow$52 million.

Table 1. Return and Demand for Capital
Rate of Return DPrivate(in millions) DSocial(in millions)
2% $72$84
4% $52$72
6% $38$62
8% $30$52
10% $26$44

Big Drug’s original demand for financial capital (DPrivate) is based on the profits received by the firm. However, other pharmaceutical firms and health care companies may learn new lessons about how to treat certain medical conditions and are then able to create their own competing products. The social benefit of the drug takes into account the value of all the positive externalities of the drug. If Big Drug were able to gain this social return instead of other companies, its demand for financial capital would shift to the demand curve DSocial, and it would be willing to borrow and invest $52 million. However, if Big Drug is receiving only 50 cents of each dollar of social benefits, the firm will not spend as much on creating new products. The amount it would be willing to spend would fall somewhere in between DPrivate and DSocial. ### Why Invest in Human Capital? The investment in anything, whether it is the construction of a new power plant or research in a new cancer treatment, usually requires a certain upfront cost with an uncertain future benefit. The investment in education, or human capital, is no different. Over the span of many years, a student and her family invest significant amounts of time and money into that student’s education. The idea is that higher levels of educational attainment will eventually serve to increase the student’s future productivity and subsequent ability to earn. Once the numbers are crunched, does this investment pay off for the student? Almost universally, economists have found that the answer to this question is a clear “Yes.” For example, several studies of the return to education in the United States estimate that the rate of return to a college education is approximately 10%. Data in Table 2, from the U.S. Bureau of Labor Statistics’ Usual Weekly Earnings of Wage and Salary Workers, Third Quarter 2013, demonstrate that median weekly earnings are higher for workers who have completed more education. While these rates of return will beat equivalent investments in Treasury bonds or savings accounts, the estimated returns to education go primarily to the individual worker, so these returns are private rates of return to education. Table 2. Usual Weekly Earnings of Wage and Salary Workers[1] Less than a High School Degree High School Degree, No College Bachelor’s Degree Median Weekly Earnings (full-time workers over the age of 25)$479 $659$1,174

What does society gain from investing in the education of another student? After all, if the government is spending taxpayer dollars to subsidize public education, society should expect some kind of return on that spending. Again, economists like George Psacharopoulos have found that, across a variety of nations, the social rate of return on schooling is also positive. After all, positive externalities exist from investment in education. While not always easy to measure, according to Walter McMahon, the positive externalities to education typically include better health outcomes for the population, lower levels of crime, a cleaner environment and a more stable, democratic government. For these reasons, many nations have chosen to use taxpayer dollars to subsidize primary, secondary, and higher education. Education clearly benefits the person who receives it, but a society where most people have a good level of education provides positive externalities for all.

### Other Examples of Positive Externalities

Although technology may be the most prominent example of a positive externality, it is not the only one. For example, being vaccinated against disease is not only a protection for the individual, but it has the positive spillover of protecting others who may become infected. When a number of homes in a neighborhood are modernized, updated, and restored, not only does it increase the value of those homes, but the value of other properties in the neighborhood may increase as well.

The appropriate public policy response to a positive externality, like a new technology, is to help the party creating the positive externality receive a greater share of the social benefits. In the case of vaccines, like flu shots, an effective policy might be to provide a subsidy to those who choose to get vaccinated.

Figure 3 shows the market for flu shots. The market demand curve DMarket for flu shots reflects only the marginal private benefits (MPB) that the vaccinated individuals receive from the shots. Assuming that there are no spillover costs in the production of flu shots, the market supply curve is given by the marginal private cost (MPC) of producing the vaccinations.

The equilibrium quantity of flu shots produced in the market, where MPB is equal to MPC, is QMarket and the price of flu shots is PMarket. However, spillover benefits exist in this market because others, those who chose not to purchase a flu shot, receive a positive externality in a reduced chance of contracting the flu. When we add the spillover benefits to the marginal private benefit of flu shots, the marginal social benefit (MSB) of flu shots is given by DSocial. Because the MPB is greater than MSB, we see that the socially optimal level of flu shots is greater than the market quantity (QSocial exceeds QMarket) and the corresponding price of flu shots, if the market were to produce QSocial, would be at PSocial. Unfortunately, the marketplace does not recognize the positive externality and flu shots will go under produced and under consumed.

So how can government try to move the market level of output closer to the socially desirable level of output? One policy would be to provide a subsidy, like a voucher, to any citizen who wishes to get vaccinated. This voucher would act as “income” that could be used to purchase only a flu shot and, if the voucher was exactly equal to the per-unit spillover benefits, would increase market equilibrium to a quantity of QSocial and a price of PSocial where MSB equals MSC. Suppliers of the flu shots would receive payment of PSocial per vaccination, while consumers of flu shots would redeem the voucher and only pay a price of PSubsidy. When the government uses a subsidy in this way, the socially optimal quantity of vaccinations is produced.

Figure 3. The Market for Flu Shots with Spillover Benefits (A Positive Externality) The market demand curve does not reflect the positive externality of flu vaccinations, so only QMarket will be exchanged. This outcome is inefficient because the marginal social benefit exceeds the marginal social cost. If the government provides a subsidy to consumers of flu shots, equal to the marginal social benefit minus the marginal private benefit, the level of vaccinations can increase to the socially optimal quantity of QSocial.

## How Governments Can Encourage Innovation

A number of different government policies can increase the incentives to innovate, including: guaranteeing intellectual property rights, government assistance with the costs of research and development, and cooperative research ventures between universities and companies.

### Intellectual Property Rights

One way to increase new technology is to guarantee the innovator an exclusive right to that new product or process. Intellectual property rights include patents, which give the inventor the exclusive legal right to make, use, or sell the invention for a limited time, and copyright laws, which give the author an exclusive legal right over works of literature, music, film/video, and pictures. For example, if a pharmaceutical firm has a patent on a new drug, then no other firm can manufacture or sell that drug for twenty-one years, unless the firm with the patent grants permission. Without a patent, the pharmaceutical firm would have to face competition for any successful products, and could earn no more than a normal rate of profit. With a patent, a firm is able to earn monopoly profits on its product for a period of time—which offers an incentive for research and development. In general, how long can “a period of time” be?

### How long is Mickey Mouse protected from being copied?

Figure 4 illustrates how the total number of patent applications filed with the U.S. Patent and Trademark Office, as well as the total number of patents granted, surged in the mid-1990s with the invention of the Internet, and is still going strong today.

Figure 4. Patents Filed and Granted, 1981–2008 The number of applications filed for patents increased substantially from the mid-1990s into the first years of the 2000s, due in part to the invention of the Internet, which has led to many other inventions and to the 1998 Copyright Term Extension Act. (Source: http://www.uspto.gov/web/offices/ac/ido/oeip/taf/us_stat.htm)

While patents provide an incentive to innovate by protecting the innovator, they are not perfect. For example:

• In countries that already have patents, economic studies show that inventors receive only one-third to one-half of the total economic value of their inventions.
• In a fast-moving high-technology industry like biotechnology or semiconductor design, patents may be almost irrelevant because technology is advancing so quickly.
• Not every new idea can be protected with a patent or a copyright—for example, a new way of organizing a factory or a new way of training employees.
• Patents may sometimes cover too much or be granted too easily. In the early 1970s, Xerox had received over 1,700 patents on various elements of the photocopy machine. Every time Xerox improved the photocopier, it received a patent on the improvement.
• The 21-year time period for a patent is somewhat arbitrary. Ideally, a patent should cover a long enough period of time for the inventor to earn a good return, but not so long that it allows the inventor to charge a monopoly price permanently.

Because patents are imperfect and do not apply well to all situations, alternative methods of improving the rate of return for inventors of new technology are desirable. Some of these possible alternative policies are described in the following sections.

### Policy #1: Government Spending on Research and Development

If the private sector does not have sufficient incentive to carry out research and development, one possibility is for the government to fund such work directly. Government spending can provide direct financial support for research and development (R&D) done at colleges and universities, nonprofit research entities, and sometimes by private firms, as well as at government-run laboratories. While government spending on research and development produces technology that is broadly available for firms to use, it costs taxpayers money and can sometimes be directed more for political than for scientific or economic reasons.

Visit the NASA website and the USDA website to read about government research that would not take place where it left to firms due to the externalities.

The first column of Table 3 shows the sources of total U.S. spending on research and development; the second column shows the total dollars of R&D funding by each source. The third column shows that, relative to the total amount of funding, 26% comes from the federal government, about 67% of R&D is done by industry, and less than 3% is done by universities and colleges.

Table 3. U.S. Research and Development Expenditures, 2008[2]
Sources of R&D Funding Amount ($billions) Percent of the Total Federal government$103.7 26.08%
Industry $267.8 67.35% Universities and colleges$10.6 2.67%
Nonprofits $12 3.02% Nonfederal government$3.5 0.88%

## Public Goods

Even though new technology creates positive externalities so that perhaps one-third or one-half of the social benefit of new inventions spills over to others, the inventor still receives some private return. What about a situation where the positive externalities are so extensive that private firms could not expect to receive any of the social benefit? This kind of good is called a public good. Spending on national defense is a good example of a public good. Let’s begin by defining the characteristics of a public good and discussing why these characteristics make it difficult for private firms to supply public goods. Then we will see how government may step in to address the issue.

### The Definition of a Public Good

Economists have a strict definition of a public good, and it does not necessarily include all goods financed through taxes. To understand the defining characteristics of a public good, first consider an ordinary private good, like a piece of pizza. A piece of pizza can be bought and sold fairly easily because it is a separate and identifiable item. However, public goods are not separate and identifiable in this way.

Instead, public goods have two defining characteristics: they are nonexcludable and nonrivalrous. The first characteristic, that a public good is nonexcludable, means that it is costly or impossible to exclude someone from using the good. If Larry buys a private good like a piece of pizza, then he can exclude others, like Lorna, from eating that pizza. However, if national defense is being provided, then it includes everyone. Even if you strongly disagree with America’s defense policies or with the level of defense spending, the national defense still protects you. You cannot choose to be unprotected, and national defense cannot protect everyone else and exclude you.

The second main characteristic of a public good, that it is nonrivalrous, means that when one person uses the public good, another can also use it. With a private good like pizza, if Max is eating the pizza then Michelle cannot also eat it; that is, the two people are rivals in consumption. With a public good like national defense, Max’s consumption of national defense does not reduce the amount left for Michelle, so they are nonrivalrous in this area.

A number of government services are examples of public goods. For instance, it would not be easy to provide fire and police service so that some people in a neighborhood would be protected from the burning and burglary of their property, while others would not be protected at all. Protecting some necessarily means protecting others, too.

Positive externalities and public goods are closely related concepts. Public goods have positive externalities, like police protection or public health funding. Not all goods and services with positive externalities, however, are public goods. Investments in education have huge positive spillovers but can be provided by a private company. Private companies can invest in new inventions such as the Apple iPad and reap profits that may not capture all of the social benefits. Patents can also be described as an attempt to make new inventions into private goods, which are excludable and rivalrous, so that no one but the inventor is allowed to use them during the length of the patent.

### The Free Rider Problem of Public Goods

Private companies find it difficult to produce public goods. If a good or service is nonexcludable, like national defense, so that it is impossible or very costly to exclude people from using this good or service, then how can a firm charge people for it?

When individuals make decisions about buying a public good, a free rider problem can arise, in which people have an incentive to let others pay for the public good and then to “free ride” on the purchases of others. The free rider problem can be expressed in terms of the prisoner’s dilemma game, which is discussed as a representation of oligopoly in Monopolistic Competition and Oligopoly. Say that two people are thinking about contributing to a public good: Rachel and Samuel. When either of them contributes to a public good, such as a local fire department, their personal cost of doing so is $4 and the social benefit of that person’s contribution is$6. Because society’s benefit of $6 is greater than the cost of$4, the investment is a good idea for society as a whole. The problem is that, while Rachel and Samuel pay for the entire cost of their contribution to the public good, they receive only half of the benefit, because the benefit of the public good is divided equally among the members of society. This sets up the prisoner’s dilemma illustrated in Table 4.

 Samuel (S) Contribute Samuel (S) Do Not Contribute Rachel (R) Contribute R pays $4, receives$6, net gain +$2 S pays$4, receives $6, net gain +$2 R pays $4, receives$3, net gain –$1 S pays$0, receives $3, net gain +$3 Rachel (R) Do Not Contribute R pays $0, receives$3, net gain +$3 S pays$4, receives $3, net gain –$1 R pays $0, receives$0 S pays $0, receives$0

If neither Rachel nor Samuel contributes to the public good, then there are no costs and no benefits of the public good. Suppose, however, that only Rachel contributes, while Samuel does not. Rachel incurs a cost of $4, but receives only$3 of benefit (half of the total $6 of benefit to society), while Samuel incurs no cost, and yet he also receives$3 of benefit. In this outcome, Rachel actually loses $1 while Samuel gains$3. A similar outcome, albeit with roles reversed, would occur if Samuel had contributed, but Rachel had not. Finally, if both parties contribute, then each incurs a cost of $4 and each receives$6 of benefit (half of the total \$12 benefit to society). There is a dilemma with the Prisoner’s Dilemma, though.

### The Problem with the Prisoner’s Dilemma

The difficulty with the prisoner’s dilemma arises as each person thinks through his or her strategic choices.

Step 1. Rachel reasons in this way: If Samuel does not contribute, then I would be a fool to contribute. However, if Samuel does contribute, then I can come out ahead by not contributing.

Step 2. Either way, I should choose not to contribute, and instead hope that I can be a free rider who uses the public good paid for by Samuel.

Step 3. Samuel reasons the same way about Rachel.

Step 4. When both people reason in that way, the public good never gets built, and there is no movement to the option where everyone cooperates—which is actually best for all parties.

### The Role of Government in Paying for Public Goods

The key insight in paying for public goods is to find a way of assuring that everyone will make a contribution and to prevent free riders. For example, if people come together through the political process and agree to pay taxes and make group decisions about the quantity of public goods, they can defeat the free rider problem by requiring, through the law, that everyone contributes.

However, government spending and taxes are not the only way to provide public goods. In some cases, markets can produce public goods. For example, think about radio. It is nonexcludable, since once the radio signal is being broadcast, it would be very difficult to stop someone from receiving it. It is nonrivalrous, since one person listening to the signal does not prevent others from listening as well. Because of these features, it is practically impossible to charge listeners directly for listening to conventional radio broadcasts.

Radio has found a way to collect revenue by selling advertising, which is an indirect way of “charging” listeners by taking up some of their time. Ultimately, consumers who purchase the goods advertised are also paying for the radio service, since the cost of advertising is built into the product cost. In a more recent development, satellite radio companies, such as SirusXM, charge a regular subscription fee for streaming music without commercials. In this case, however, the product is excludable—only those who pay for the subscription will receive the broadcast.

Some public goods will also have a mixture of public provision at no charge along with fees for some purposes, like a public city park that is free to use, but the government charges a fee for parking your car, for reserving certain picnic grounds, and for food sold at a refreshment stand.

In other cases, social pressures and personal appeals can be used, rather than the force of law, to reduce the number of free riders and to collect resources for the public good. For example, neighbors sometimes form an association to carry out beautification projects or to patrol their area after dark to discourage crime. In low-income countries, where social pressure strongly encourages all farmers to participate, farmers in a region may come together to work on a large irrigation project that will benefit all. Many fundraising efforts, including raising money for local charities and for the endowments of colleges and universities, also can be viewed as an attempt to use social pressure to discourage free riding and to generate the outcome that will produce a public benefit.

### Common Resources and the “Tragedy of the Commons”

There are some goods that do not fall neatly into the categories of private good or public good. While it is easy to classify a pizza as a private good and a city park as a public good, what about an item that is nonexcludable and rivalrous, such as the queen conch?

In the Caribbean, the queen conch is a large marine mollusk found in shallow waters of sea grass. These waters are so shallow, and so clear, that a single diver may harvest many conch in a single day. Not only is conch meat a local delicacy and an important part of the local diet, but the large ornate shells are used in art and can be crafted into musical instruments. Because almost anyone with a small boat, snorkel, and mask, can participate in the conch harvest, it is essentially nonexcludable. At the same time, fishing for conch is rivalrous; once a diver catches one conch it cannot be caught by another diver.

Goods that are nonexcludable and rivalrous are called common resources. Because the waters of the Caribbean are open to all conch fishermen, and because any conch that you catch is conch that I cannot catch, common resources like the conch tend to be overharvested.

The problem of overharvesting common resources is not a new one, but ecologist Garret Hardin put the tag “Tragedy of the Commons” to the problem in a 1968 article in the magazine Science. Economists view this as a problem of property rights. Since nobody owns the ocean, or the conch that crawl on the sand beneath it, no one individual has an incentive to protect that resource and responsibly harvest it. To address the issue of overharvesting conch and other marine fisheries, economists typically advocate simple devices like fishing licenses, harvest limits, and shorter fishing seasons. When the population of a species drops to critically low numbers, governments have even banned the harvest until biologists determine that the population has returned to sustainable levels. In fact, such is the case with the conch, the harvesting of which has been effectively banned in the United States since 1986.

Visit this website for more on the queen conch industry.

### Positive Externalities in Public Health Programs

One of the most remarkable changes in the standard of living in the last several centuries is that people are living longer. Thousands of years ago, human life expectancy is believed to have been in the range of 20 to 30 years. By 1900, average life expectancy in the United States was 47 years. By the start of the twenty-first century, U.S. life expectancy was 77 years. Most of the gains in life expectancy in the history of the human race happened in the twentieth century.

The rise in life expectancy seems to stem from three primary factors. First, systems for providing clean water and disposing of human waste helped to prevent the transmission of many diseases. Second, changes in public behavior have advanced health. Early in the twentieth century, for example, people learned the importance of boiling bottles before using them for food storage and baby’s milk, washing their hands, and protecting food from flies. More recent behavioral changes include reducing the number of people who smoke tobacco and precautions to limit sexually transmitted diseases. Third, medicine has played a large role. Immunizations for diphtheria, cholera, pertussis, tuberculosis, tetanus, and yellow fever were developed between 1890 and 1930. Penicillin, discovered in 1941, led to a series of other antibiotic drugs for bringing infectious diseases under control. In recent decades, drugs that reduce the risks of high blood pressure have had a dramatic effect in extending lives.

These advances in public health have all been closely linked to positive externalities and public goods. Public health officials taught hygienic practices to mothers in the early 1900s and encouraged less smoking in the late 1900s. Many public sanitation systems and storm sewers were funded by government because they have the key traits of public goods. In the twentieth century, many medical discoveries came out of government or university-funded research. Patents and intellectual property rights provided an additional incentive for private inventors. The reason for requiring immunizations, phrased in economic terms, is that it prevents spillovers of illness to others—as well as helping the person immunized.

### The Benefits of Voyager I Live On

While we applaud the technology spillovers of NASA’s space projects, we should also acknowledge that those benefits are not shared equally. Economists like Tyler Cowen, a professor at George Mason University, are seeing more and more evidence of a widening gap between those who have access to rapidly improving technology, and those who do not. According to Cowen, author of the recent book, Average Is Over: Powering America Beyond the Age of the Great Stagnation, this inequality in access to technology and information is going to deepen the inequality in skills, and ultimately, in wages and global standards of living.

### Glossary

free rider those who want others to pay for the public good and then plan to use the good themselves; if many people act as free riders, the public good may never be provided

intellectual property the body of law including patents, trademarks, copyrights, and trade secret law that protect the right of inventors to produce and sell their inventions

nonexcludable when it is costly or impossible to exclude someone from using the good, and thus hard to charge for it

nonrivalrous even when one person uses the good, others can also use it

positive externalities beneficial spillovers to a third party or parties

private benefits the dollar value of all benefits of a new product or process invented by a company that can be captured by the investing company

private rates of return when the estimated rates of return go primarily to an individual; for example, earning interest on a savings account

public good good that is nonexcludable and nonrivalrous, and thus is difficult for market producers to sell to individual consumers

social benefits the dollar value of all benefits of a new product or process invented by a company that can be captured by other firms and by society as a whole

social rate of return when the estimated rates of return go primarily to society; for example, providing free education