[1] Callicott held the position of Professor of Philosophy and Natural Resources at the University of Wisconsin–Stevens Point from 1969 to 1995, where he taught the world's first course in environmental ethics in 1971.
Callicott's Earth's Insights (1994) is also considered an important contribution to the budding field of comparative environmental philosophy; a special edition of the journal Worldviews: Environment, Culture, Religion (Volume 1, Number 2) was devoted to scholarly reviews of the work.
[5] Callicott is co-Editor-in-Chief with Robert Frodeman of the award-winning, two-volume A-Z Encyclopedia of Environmental Ethics and Philosophy, published by Macmillan in 2009.
[1] His dissertation, titled Plato's Aesthetics: An Introduction to the Theory of Forms, drew from the concentration of his undergraduate and graduate work: ancient Greek philosophy.
There, as faculty advisor to the Black Students Association, he was active in the Southern Civil Rights Movement during the time of Martin Luther King Jr.’s last campaigns in the area.
Callicott writes that “the landscape that had helped shape and inspire the nascent evolutionary-ecological thought of the youthful Muir and that of the mature Leopold was the perfect setting for (me) to inaugurate (my) life-long vocation as a founder of academic environmental philosophy.”[9] In 1995, he joined the Department of Philosophy and Religion Studies at the University of North Texas in Denton.
Actual environmental concerns, however, focus on transorganismic entities: endangered species; threatened biotic communities and ecosystems; rivers and lakes; the ocean and atmosphere.
[16] Darwin argues that these “moral sentiments” evolved as the sine qua non of social (or communal) solidarity, on which depends the survival and reproductive success of the individual members of society (or community).
[18] Among such matters of fact, reason both traces the often complex causal chain of the consequences of various actions and discloses the proper objects of the moral sentiments.
Accordingly, Leopold also traces both the causal chain of ecological consequences of such seemingly innocent actions as tilling the soil and grazing cattle and discloses a proper object of those moral sentiments — such as loyalty and patriotism — which are excited by social membership and community identity.
Aldo Leopold, according to Callicott, provides reasons why non-human species, biotic communities, and ecosystems should be valued intrinsically (and thus not severely compromised or destroyed).
Of wildflowers and songbirds, for example, species with little instrumental value, Leopold writes in Sand County's "The Land Ethic": "Yet these creatures are members of the biotic community, and if (as I believe) its stability depends on its integrity, they are entitled to continuance.
Exported to other regions of the world, such as Africa and India, where indigenous peoples still thrive, the wilderness idea has been used to justify their eviction and dispossession in the name of national parks.
Callicott instead proposes that, because wilderness areas serve purposes of biological conservation, they should be reconceived more fittingly as "biodiversity reserves.
[31] If members of overpopulous species, such as deer, ought to be "culled" or "harvested," in the name of preserving the integrity, stability, and beauty of the biotic community, and if staggeringly overpopulous Homo sapiens is also but "a plain member and citizen' of the biotic community, then why should culling and harvesting humans be any less obligatory?
[33] This reply led to another criticism: that Callicott provides no "second-order principles" to prioritize duties to fellow humans and those to the biotic community when they conflict.
[40] As Andrew Light observes, Callicott does not insist that the Leopold land ethic is based on the uniquely true worldview of evolutionary biology and ecology.
And finally, as to beauty, Darwin himself observed in the final sentence of the Origin that “There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”[43] Most recent criticisms have been leveled at Callicott's works addressing the idea of wilderness, the sanctum sanctorum of the twentieth-century environmental movement.
Some scholars acknowledge the intellectual merits of Callicott's critique of the wilderness idea, but regard it as both a betrayal of one of Aldo Leopold's most cherished causes and as giving aid and comfort to the environmental movement's enemies.