It's no secret that conservation is rife with controversies these days. Are novel ecosystems acceptable outcomes in some settings? Is it possible or even desirable to eradicate exotic invasive species in all circumstances? Should managers impose radical interventions, such as assisted migration, to offset the risk of losses under climate change? Should conservation be focused on preserving nature, serving human needs, or both? Are ecosystem services useful currencies for policy or a crude monetization of nature? Most of these debates represent tensions between conservation philosophy and practice that arose in the mid‐20th century and ideas, initiatives, and approaches that have bubbled up from various quarters over the past two decades. Protagonists on what might be called the precautionary side express concerns over reversal of the gains achieved by 20th‐century conservation efforts, diversion of attention from nature and natural processes, and emplacement of slippery slopes to perdition (eg any concession to an invasive species or novel ecosystem opens the way to “anything goes”).

I sympathize with these viewpoints; I became an ecologist during the 1970s and shared many of these views. However, I came to embrace most of the newer alternatives – at first gradually, then rapidly. Anthropogenic climate change, together with my own research on ecological responses to past climate changes, led me to rethink many of my most closely held assumptions and beloved values. Climate change altered the rules. And as I worked more closely with resource managers and conservation practitioners, I realized that these philosophical disputes were not top concerns. Although my sample size is small and the sampling opportunistic, it seems that many – perhaps most – managers do not feel threatened by the new ideas emerging in conservation, and many actively embrace those ideas because it enables them to do their jobs more effectively. This is not to say that they are happy about disruptive invasives in vulnerable places, or that replacement of natural ecosystems by novel ones doesn't concern them. But they are keenly aware that their decisions and interventions are situation‐dependent, and many view the broader controversies as largely academic disputes.

Conservation represents a grand intersection of science and values; “science‐free” practice is uninformed, and “value‐neutral” applications are illusory. Both science and values evolve over time. What counts as scientific practice, knowledge, and explanation has evolved considerably since the 17th century, and many things we do or take for granted now would have seemed absurd or impermissible a century ago. At the same time, we still use approaches, knowledge, and inferential methods devised three or four centuries ago. By the same token, societal values also change; in three centuries, the perception of mountain landscapes in Western culture has developed successively from desolate wastelands to troves of mineral and timber wealth to places of sublime beauty and inspiration to sources of clean water.

Today's conservation was largely invented in the mid to late 20th century, a period of rapid change in both science and society. It emerged when scientific views of ecological systems were relatively static, and largely before we understood how climate change influenced ecological states. It arose before the ecological influence of prehistoric peoples was widely appreciated, and at a time when indigenous peoples and traditional knowledge were far more marginalized than they are now. The mid‐20th century efflorescence of conservation not only incorporated contemporary science and values, but also drew on earlier versions of conservation, from the Progressive, Romantic, Enlightenment, and colonial eras. It represents only the most recent of a series of reinventions spanning the past five centuries.

We are living amidst another reinvention of conservation, bringing it into better alignment with advances in scientific understanding and practice, and with developments in our collective and individual values. Most transformations in science and society are evolutionary, not revolutionary; sound ideas and values are modified, not discarded. We still use 17th‐century physics for routine earthly purposes, recognizing that we've learned a lot since Newton. In the US, we still govern ourselves using a four‐page, handwritten document from the late 18th century, recognizing that it leaves room for new interpretations and amendments. We can, and must, build on the important gains and successes of the past few decades in order to make further progress. Fundamental change is never free of controversy. But just as organisms evolve and adapt to the challenges posed by a changing environment, conservation must adapt and reinvent itself to meet the challenges of a rapidly changing world.