What is environmentalism? If you ask five people you may get five distinct answers. Some think this is a big problem; I disagree.

Many people trace environmentalism’s U.S. roots to Teddy Roosevelt, John Muir, and Aldo Leopold. Interestingly, however, the advance of the modern environmental movement that coalesced during the late 1960s and early 1970s was focused much more on environmental pollution and human quality of life issue than on nature preservation. The Clean Air and Clean Water Acts were passed to address the health impacts of smog and our heavily polluted waterways. Even though Rachel Carson’s Silent Spring discussed the potential extinction of species, her concern was driven primarily by toxic emissions and less so by habitat preservation. The most notable campaigns focused exclusively on species protection revolved around “charismatic megafauna” like whales, dolphins, elephants, tigers, etc.

These days, many people tend to associate environmentalism with the concept of “sustainability," though this term didn’t really enter the environmental lexicon until the late 1980s and early 1990s. “Sustainability” is a vague concept. It is most sensibly applied to maintaining sustainable populations of species, or ecosystems that are resilient to shock, but in many circles it has come to signify much more.

In particular, many people have tried to combine the concept of sustainability with economic development — hence the term “sustainable development” — as a way to include many of the socioeconomic concerns poor people face (particularly in natural resource-dependent developing countries). This highlights one of the longstanding and ongoing tensions within the environmental movement: does it pay enough attention to the needs of the poor, or is it more a way to maintain natural environments for the benefit of the rich?

Another problem with exclusive focus on sustainability is that many problems we face revolve more around improving quality of life than sustaining any particular set of environmental resources. A rigid adherence to purely scientific views of sustainability can easily devolve into protection of the status quo, and becomes problematic for anyone who believes that how we treat the non-human world is a core facet of environmentalism.

Environmentalism’s strength lies in its diverse and wide group of supporters. We may not all agree on everything, but an over-arching respect for life on earth has proven sufficiently unifying to keep the movement afloat and achieving significant victories. Let us not forget that this diversity is more of a strength than a weakness; we should always welcome debate on what we are, what we do, and why we do it.