What’s not to like about charitable giving based on quantitative evidence and aimed at maximum impact? Actually, I have a few misgivings.

First, on individuals and institutions: although greater altruistic feeling and behavior should be an unmitigated good, assigning to individuals and groups the roles typically reserved for societal institutions poses some dangers. We expect local and national law enforcement to fight crime, for instance. We may at first welcome vigilantes but soon discover their actions are fueled by bias, group psychology, and unchecked power. Even worse, they may start eroding society’s trust in public institutions. Why should we pay for police when others protect us?

In the case of philanthropy, the problem isn’t street justice but replacing the government’s role in, say, providing health care. “So what?” one might ask, given the track record of some states. But consider the long-term consequences. When key services we expect from states are taken over by other entities, building trust in the state and developing state capacity in other crucial areas may become harder. Correspondingly, convincing people to engage in politics and oversight of the state also becomes more difficult. In much of the developing world, from Pakistan to Nigeria or Haiti, where state-society relations are already frayed, they may become harder to mend.

Effective altruism might influence what society views as a meaningful life.

Second, on effective measurement: we cannot measure accurately which organizations use resources most effectively. More evidence is always preferred, but precise measurement of the social value of a donated dollar may be impossible. What is the social value of a dollar given to Amnesty International as opposed to Oxfam or an NGO providing vaccines or textbooks? Every measurement involves value judgments. How much more valuable is to save the life of a one-year-old than to send a six-year-old to school?

But the problem is thornier still. A large body of research shows that economic development is the best way to lift millions out of poverty and improve their health, education, and access to public amenities. So one has to take into account how charities’ activities affect economic development, which is essentially impossible. If, as some economists and political scientists suggest, changes in political and economic institutions are critical for long-run economic growth, then watchdog organizations such as Amnesty may be essential for transforming dysfunctional regimes. Effective altruists don’t (yet?) see the importance of these more political organizations. If this narrow focus continues, it may divert public and media priorities from political factors underpinning economic development.

Finally, on what we value as a society: effective altruists’ imperative to maximize their earnings so they can give more might influence what society views as a meaningful life. Many of us would consider the life of a young person who foregoes the comforts of a well-paying job to work as a community activist or a doctor in a war zone not just meaningful but also highly valuable for society. But effective altruism may slowly chip away at this conception.

Perhaps Bill Gates, who has made billions and is now giving large sums to worthy causes, should be emulated. Or perhaps we should become Wall Street traders to maximize our earnings and donations. Peter Singer says there is no justification for breaking the law or engaging in blatantly unethical behavior to do so, but life’s choices seldom come in black and white. Imagine that the Department of Justice and the European Commission had not prevented Microsoft from forming a more effective software monopoly; Gates’s wealth could then be twice what it is today, and he could give twice as much. Would his have been a more meaningful and socially valuable life, even if his additional earnings came at the expense of monopoly distortions of the software market? Or suppose our Wall Street trader—now engaged in the sort of high-frequency, algorithmic arbitrage many economists view as socially useless at best—had become an innovator, earning less and giving less but creating tools that millions find valuable. Would hers be a less meaningful life? What about civic duty—being an informed citizen, an active political participant ready to speak out against injustice, and a member of society willing to help others directly? Is that not part of a meaningful life?

None of these objections will have much force if effective altruists remain a small, marginal tribe. But we may yet see the best and brightest in our colleges and high-prestige professions join them. If that happens, the unforeseen consequences of this powerful but flawed idea could be stark.