Ethics of terraforming

The ethics of terraforming has constituted a philosophical debate within biology, ecology, and environmental ethics as to whether terraforming other worlds is an ethical endeavor.

On the pro-terraforming side of the argument, there are those like Robert Zubrin and Richard L. S. Taylor who believe that it is humanity's moral obligation to make other worlds suitable for Terran life, as a continuation of the history of life transforming the environments around it on Earth. They also point out that Earth will eventually be destroyed as nature takes its course, so that humanity faces a very long-term choice between terraforming other worlds or allowing all Earth life to become extinct. Dr. Zubrin further argues that even if native microbes have arisen on Mars, for example, the fact that they have not progressed beyond the microbe stage by this point, halfway through the lifetime of the Sun, is a strong indicator that they never will; and that if microbial life exists on Mars, it is likely related to Earth life through a common origin on one of the two planets, which spread to the other as an example of panspermia. Since Mars life would then not be fundamentally unrelated to Earth life, it would not be unique, and competition with such life would not be fundamentally different from competing against microbes on Earth.

Dr. Zubrin summed up this view:

Richard Taylor more succinctly exemplified this point of view with the slogan, "move over microbe".

Some critics label this argument as an example of anthropocentrism. These critics may view the homocentric view as not only geocentric but short-sighted, and tending to favour human interests to the detriment of ecological systems. They argue that an anthropocentrically driven approach could lead to the extinction of indigenous extraterrestrial life, or the Interplanetary contamination.

Martyn J. Fogg rebutted these ideas by delineating four potential rationales on which to evaluate the ethics of terraforming—anthropocentrism, zoocentrism, ecocentrism, and preservationism—roughly forming a spectrum from placing the most value on human utility to placing the most value on preserving nature. While concluding that arguments for protecting alien biota can be made from any of these standpoints, he also concludes with an argument, similar to Zubrin's, that strict preservationism is "untenable", since "it assumes that human consciousness, creativity, culture and technology stand outside nature, rather than having been a product of natural selection. If Homo sapiens is the first space faring species to have evolved on Earth, space settlement would not involve acting 'outside nature', but legitimately 'within our nature'."

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