It is important to isolate the genuine disagreements laid out by Greenwald, Noss, and their respective colleagues. Greenwald and colleagues misinterpreted our overview of conservation science (Kareiva and Marvier 2012) as prescriptive, when in fact it was primarily descriptive of how the field has developed over the last 30 years. We asked, “What is conservation science?” and not, “What should conservation science become?” We agree with Greenwald and colleagues that conservationists are increasingly examining the costs and benefits to society, incorporating perspectives from the social sciences and humanities, and focusing on lands subject to resource extraction. Moreover, when we emphasized the need for evidence-based conservation, it was precisely because we do value “solid evidence from experimentation and observation.” The point of evidence-based conservation is to use a weight-of-evidence approach to understand which practices are most successful under what conditions and to then use the findings to guide conservation practice.
Another false disagreement arises when Noss and colleagues chastise us for saying that humans need not set limits to our domination of nature. In fact, we stated the opposite: “The ability of nature to recover… does not provide humans license to inflict unfettered environmental damage.” Noss and colleagues miscast our discussion of how to motivate good stewardship of nature and the suggestion that working with corporations might better manage the ill effects of economic activity as an ethical debate. We were not attempting to develop a “mature conservation ethic”—a task that we would leave to environmental philosophers. Instead, we were advancing the testable hypothesis that major conservation benefits will accrue from working with, rather than against, corporations. Similarly, when we point out that moving people off their land can backfire, this is not a call to abandon the protected-area strategy. It is an observation and a prompt both to improve protected-area strategies and to supplement them with interventions focused on the spaces between protected areas, as many conservation groups are doing.
However, not all of the disagreement is contrived. Noss and colleagues besmirch compromise and see a dichotomous choice in which society will either protect nature or advance human well-being. We reject the inevitability of this choice. Increasingly, conservationists are finding synergies where once we saw only trade-offs. Just as one example, the Gates Foundation's Reinvent the Toilet Challenge seeks sustainable sanitation solutions that could not only reduce disease but, if they are deployed in coastal communities of the Caribbean, could also reduce pollution that kills coral reefs, thereby benefiting both nature and people. Strategies that serve both people and nature can broaden the political and financial support for conservation (Marvier and Wong 2012). Although we agree that economic activities are the source of many conservation problems, we do not conclude that economic growth per se is the foe of conservation.
Like our critics, we want a world with large, relatively untrammeled open spaces and a world that does not suffer the loss of species both great and small. We want a world in which people have the opportunity to enjoy the surprises and inspiration of nature. The question is how we most effectively achieve this future in which both nature and people thrive. We would place more bets than would Noss and his coauthors on working with corporations, on pursuing rights-based management (community or private) of resources rather than exclusion or no-take zones, and on making a promise that conservation do no harm to people. We are all passionate about conservation—and just as conservationists prize the diversity of plants and animals and the evolutionary processes that shape them (Soulé 1985), the field might do well to similarly advance a diversity of approaches and then let science—both natural and social science—be the arbiter of which strategies are most effective.