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As a general category of ethical or moral theories, consequentialism refers to theories that evaluate rightness or wrongness based exclusively on the consequences or effects of an act or acts. Consequentialist theories may differ over what kinds of consequences matter, while agreeing that the rightness or wrongness of actions cannot be based on motives or intentions of those who act, nor on the conformity of the act to duty, virtue, piety, moral rules, or the law. Consequences are all that matter for ethics, on this view. According to consequentialists, some murders might turn out to be morally right, while some acts of sincere generosity might be wrong.

Consequentialism is the ethical theory most compatible with the empirical and quantitative focus of much of science and technology. When a consequentialist studies ethical issues in science and technology, an act is usually understood broadly to include national and local policies, programs, distributions of resources, implementations of new technologies, and the like. Consequentialism seems particularly well suited to evaluate these kinds of complex acts, because it shares with modern, positivistic science an emphasis on observation. Just as one might form and test a hypothesis about electromagnetic radiation, so too could one test an act or policy that one believes to be right. In both cases, one looks to results in the real world in order make an evaluation.

Also, consequentialist theories take into account short- and long-term effects, and hence can evaluate developments such as nuclear power, where the immediate good effects (electricity without air pollution) may be outweighed by later harmful effects (radioactive waste, illness). In focusing on observable effects over time, consequentialists seem to look in the obvious places for answers to ethical questions concerning emerging technologies. To evaluate such complicated developments as genetic engineering, nanotechnology, the Internet, or even automobile transportation, where else would one look but to the effects?

Despite the intuitive appeal of consequentialism for such ethical inquiries, the view has faced serious opposition, especially from philosophers, as its proponents try to specify which consequences are relevant to moral evaluation. The historical development of consequentialism shows a constant struggle to identify the morally relevant effects of acts and to measure them. Consequentialists have sought to elucidate a scientific ethical theory for difficult contemporary issues, but with mixed results.

The Classical View: Act Utilitarianism

The most influential version of consequentialism is known as utilitarianism. The basic idea behind this view is quite simple. One consequence that almost anyone would want from an act is an increase in happiness, because happiness is undeniably a good. This is the conception of the good from which utilitarianism begins, and further developments in utilitarian theory almost always get back, in some way, to the content and measure of happiness.

Utilitarians are not merely interested in their own happiness; they advocate the "greatest happiness of the greatest number." According to the founder of classical or act utilitarianism, Jeremy Bentham (1748–1832), an act is right if its overall tendency is to increase the proportion of happiness (or pleasure) to pain.

If one has a choice between several acts in some situation, one ought to choose the act with the best net effect on utility. In some cases this will be the act that increases everyone's utility. In other cases, the best act would do no more than decrease everyone's pain. For most complex acts and policies, though, the result is complicated; the same act may include both some utility and some disutility. Hence Bentham realized that he would need a quantitative method for calculating the best utilitarian act. He proposed a "felicific calculus" that attempted (unsuccessfully) to supply cardinal measurements for the utility of an act based on its intensity, duration, certainty, and similar factors. By summing measurements for every act over all those who would be affected, utilitarians could instruct society on how incrementally to increase the amount of utility its members enjoyed. Act utilitarianism, if carried out rigorously, promised a program of social reform. For individuals who used the theory to evaluate their acts, the calculus required them to count the happiness of others as though it were their own. In principle, it provided an argument for an impartial and equitable distribution of the fruits of the new industrial revolution.

Another significant aspect of Bentham's view is that his principle of utility seeks, in the long run, to maximize the utility of all sentient beings—every being that can feel pleasure or pain. In this way his theory grants moral status not just to humans, who alone can reason and talk, but also to any animal that can feel or suffer. Bentham argued that the pain of non-human animals must count in the felicific calculus; his view would inspire later animal rights advocates and contemporary utilitarians such as Peter Singer. Utilitarianism thus became the first modern moral theory to take seriously the harm done by humans to other animals.

Despite its progressive social and political tendencies, act utilitarianism faced major problems. Even if individuals could calculate a cardinal measurement of personal utility from a particular act, they could not be sure that this measurement was on the same scale as a measurement for another person. But the theory requires the summing of utilities over the class of those affected by the act. Utilitarianism requires cardinal interpersonal measurements of utility—numbers on the same scale, valid for everyone. Supposing that the theory could provide such a scale, it then seemed to demand constant calculation for every act, because what is required morally is to come up with the greatest sum of utility. Every option in acting would have to be considered, and such exhaustive calculations might lead to paralysis.

Finally, act utilitarianism seemed to embrace a brutish theory of the good; the pleasure of thousands of cows, chewing their cud, might outweigh the utility of a college education for one person. If there were tradeoffs to be made—and the emerging free markets of Bentham's time made those tradeoffs possible—one might end up with many satisfied cows instead of a few educated people. Worse still, act utilitarianism might ask a sacrifice of the rights of some for the utility of others. Because every good was to be reduced to utility, even future commitments of justice seemed to be beholden to the arithmetic of maximization.

Rule Utilitarianism

Bentham's protégé, John Stuart Mill (1806–1873), addressed some of the shortcomings of act utilitarianism by proposing three changes. First, he found Bentham's ethical calculations too cumbersome, and proposed instead that society adopt and enforce a set of rules which, when followed, were likely to produce the highest overall utility. The best way to be a utilitarian, on this view, would be to act according to a rule that, in conjunction with other rules, prescribed behavior that maximized total social utility. One rule could replace another in the set, provided that the change would contribute to greater overall utility. But absent now in Mill's rule utilitarianism was the requirement—or even the possibility—of a quantitative calculus for determining which acts to choose. Second, Mill introduced a qualitative distinction between higher and lower pleasures, thus undermining the notion of a common scale for ethical measurement, and implicitly relegating the happiness of non-human animals to insignificance. Finally, Mill argued that certain rules, what he called the rules of justice, were so important to the long-term security (and hence happiness) of society that they must be considered practically inviolable. The results of these changes made the application of rule utilitarianism less scientific but much more in line with common sense morality. Mill's theory still shared the goal of Bentham's original utilitarianism, but it allowed notions such as duties, rights, and virtues to be means to the end of increased social utility.

Market Consequentialism

By the early twentieth century, utilitarian moral philosophers and economists became interested in market activity as a replacement for the direct measurement of the consequences of an act. They saw preferences, revealed in market supply and demand, as an approximate (though indirect) indication of the utility that a single person gains by a market "act." They also were able to represent mathematically an individual's preferences over bundles of goods, and to prove some interesting theorems about these "utility functions" of individuals. By analyzing market preferences, economic consequentialists could provide quantifiable evidence of what made consumers happy. To be a consequentialist about market preferences meant to choose the act or policy that allowed all persons their highest-ordered preferences, given what an economy could supply.

The economic version of utilitarianism was made even more sophisticated by the addition of a formal theory of individual choice under uncertainty, introduced by John von Neumann and Oskar Morgenstern (1944). Their theory generated cardinal measurements of expected utilities for strategic individual choices, given plausible assumptions about an individual's utility function. Working from the results of von Neumann and Morgenstern, John Harsanyi (1955) would later provide a complementary justification of utilitarianism for social choice by employing the notion of a "social welfare function." By the end of the twentieth century, economists had transformed ethical questions over how to reach the best consequences into economic questions over how to increase market activity, trade, social welfare, and global production.

The economic consequentialists have influenced many other fields. In jurisprudence, a theory known as the economic analysis of law has advocated the interpretation of legal concepts so as to maximize wealth. In business and public policy, the cost-benefit analysis has been introduced as a decision procedure for large-scale projects. A question such as where to dump toxic waste, when addressed by the cost-benefit analysis, provides a utilitarian solution to disputes by reference to the hypothetical willingness to pay of the interested parties affected by the possible outcomes of the decision. It is not surprising then that hypothetical willingness to pay is affected by the actual ability to pay, and so the fact that dump sites end up in poor neighborhoods is explained by this "ethical" decision procedure. The Nobel laureate Amartya Sen (1970, 1985) has been the most important critic of utilitarian economics on these issues. His contributions to the debate have focused on poverty, development, and the measurement of "capability" (as opposed to raw utility) in accounting for the bases of social choice.

Pluralist Conseqentialism

Many contemporary philosophers worry that developments in utilitarian theory have undermined the spirit of consequentialism. They point out that the everyday conception of human flourishing is not as thin as wealth maximization. The British philosopher G.E. Moore even advocated an "ideal" utilitarianism that got rid of the notion of pleasure as the good, and replaced it with the good of aesthetic experience and friendship (1993). It now seems clear that, while utility may be a good, and wealth one approximation of it, there are many other goods that do not reduce to either utility or wealth. By adopting a pluralist conception of goods, critics of utilitarianism allow into the ethical decision process notions like interests, rights, human freedom, biodiversity, sustainability, and other non-economic values.

The pluralists continue to maintain that what is right to do is decided by reference exclusively to consequences—but now the list of goods in the accounting is much broader than utility. Here talk of maximization no longer makes sense; the goal is to optimize the plural goods that result from acts or policies. Stakeholder theory is one such form of consequentialism, because it tries to tailor corporate decisions to the interests of all those who have a stake in the workings of the company, and not merely to those who hold stock in it.

Special Challenges

How useful is consequentialism when one morally evaluates technologies? A particular area of ethical concern is the effect of current and near-term technologies on future generations. Nuclear power, genetic engineering, human cloning, genetic modification of food, and other momentous programs will all have effects far into the future. Some versions of consequentialism would require a counting of the effects on those who are not yet alive, even though their preferences cannot be known, and actions and choices have not yet had an impact on them. It may be assumed that, if they live, they will want clean air to breathe, clean water, safe food, and other such necessities. Harms to distant generations may be discounted by some factor, but should not be neglected entirely, for then all the consequences of acts and policies are not taken into account.

Beyond the uncertainty of how much to discount, there is a deep problem for consequentialism that has been called by Derek Parfit (1984) the "non-identity problem." One assumes that the broad technological choices that are made now could harm particular people in future generations. But a consequentialist in some future generation could not complain that current policies and choices made his or her life worse off, because the things done now will affect who is actually born. That person will not exist, unless people currently living do exactly the good or bad things that they end up doing. Changes in manufacturing, travel, city planning, leisure, and work will determine which future people will meet and partner, and at what point in time they will produce children. The same is true for changes in technology. Similarly, for actual persons alive in the early twenty-first century, it is extremely unlikely that they would have been conceived were it not for the transportation systems, migration patterns, world wars, and other life aspects of their parents.

Philosophical debate over consequentialism is likely to persist. Nonetheless, its focus on observable results and effects will keep it in the center of ethical inquiries where science and technology are concerned.


SEE ALSO Economics and Ethics; Engineering Ethics; Mill, John Stuart.


Bentham, Jeremy. (1989 [1789]). On the Principle of Morals and Legislation. New York: Oxford University Press. A foundational text in moral philosophy and political economy.

Harsanyi, John. (1955). "Cardinal Welfare, Individualistic Ethics, and Interpersonal Comparisons of Utility. Journal of Political Economy 63: 309–321. Essay connecting classical utilitarianism and the social welfare function in economics.

Mill, John Stuart. (1998 [1863]). Utilitarianism. Oxford, UK: Oxford University Press. Classic text in moral philosophy, arguing for utilitarianism in new dress, with a "proof" of the general principle of utility, a defense of rules (especially rules of justice), and novel arguments for qualitative distinctions in pleasures.

Moore, G.E. (1993 [1903]). Principia Ethica. Cambridge, UK: Cambridge University Press. Features a criticism of utilitarianism from within the tradition of analytic philosophy, and offers a reformulation in terms of "ideal utilitarianism."

Parfit, Derek. (1990 [1984]). Reasons and Persons. Oxford, UK: Oxford University Press. Includes a sophisticated analysis of utilitarianism and the problem of future generations.

Sen, Amartya Kumar. (1970). Collective Choice and Social Welfare. San Francisco: Holden-Day Inc. Sophisticated overview of work in utilitarian economic theory.

Sen, Amartya Kumar. (1985). Commodities and Capabilities. Amsterdam: Elsevier Science Publishers. Short but important book—from Sen's Hennipman lecture in Amsterdam—which introduces the "capability" measure into utilitarian social welfare calculations.

Singer, Peter. (1990). Animal Liberation, 2nd edition. New York: New York Review of Books. Widely read attack on "speciesism" and defense of the consideration of animal welfare on utilitarian grounds.

Smart, J.J.C., and Williams, Bernard. (1990). Utilitarianism: For and Against. Cambridge, UK: Cambridge University Press. Offers an outline and a critique of a new system of utilitarian ethics.

von Neumann, John, and Morgenstern, Oskar. (1944). Theory of Games and Economic Behavior. Princeton, NJ: Princeton University Press. Classic text in the formal theory of choice under uncertainty.

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