Arne Dekke Eide Næss (pronounced /ˈɑːr nə ˈnɛs/; 27 January 1912 – 12 January 2009) was a Norwegian philosopher who created the term "deep ecology." He was an important and inspiring person in the environmental movement of the late 1900s. He also wrote many books about other philosophical topics. Næss said that Rachel Carson’s 1962 book Silent Spring greatly influenced his ideas about deep ecology. He combined his ideas about nature with the principles of nonviolence from Mahatma Gandhi and took part in direct action efforts.

Næss believed that environmental groups in the early years after World War II helped people understand environmental problems, but they did not fully recognize or address the deeper cultural and philosophical causes of these issues. He argued that the environmental problems of the 20th century were caused by certain unspoken beliefs and attitudes in modern Western societies that were not widely acknowledged.

Næss made a clear difference between two types of thinking about nature: "deep" and "shallow" ecology. Unlike the practical approaches of Western businesses and governments, which focused on benefits and uses, he believed that truly understanding nature means seeing the value of all living things. He emphasized that every creature depends on others in the complex web of life that makes up the natural world.

Life and career

Arne Næss was born in Slemdal, Oslo, Norway. His parents were Christine (Dekke) and Ragnar Eide Næss. Ragnar was a successful banker, and Arne was the younger brother of Erling Dekke Næss, a shipowner. Næss had two children with his first wife, Else. He was also the uncle of Arne Næss Jr., a mountaineer and businessman who lived from 1937 to 2004.

In 1939, Næss became the youngest person to be named a full professor at the University of Oslo. At that time, he was the only professor of philosophy in Norway.

Næss was known for his love of mountain climbing. In 1950, he led a group that reached the top of Tirich Mir, a mountain in Pakistan that is 7,708 meters (25,289 feet) high. This event was shown in a documentary called Tirich Mir til topps. The Tvergastein hut, located in the Hallingskarvet mountain range, was important to Næss’s philosophy called "Ecosophy T." The letter "T" in this philosophy represents the Tvergastein hut.

In 1958, Næss started a journal called Inquiry, which covers many areas of philosophy.

In 1970, Næss joined many protesters who tied themselves to rocks near Mardalsfossen, a waterfall in a Norwegian fjord. They refused to move until plans to build a dam were canceled. Although the dam was later built and the protesters were removed by police, the event helped start a more active movement for environmental protection in Norway.

At age 61, while teaching at the University of Hong Kong, Næss met Kit-Fai Tsui, a philosophy student who was 40 years younger. They married 17 years later.

In 1996, Næss received the Swedish Academy Nordic Prize, often called the "little Nobel." In 2005, he was honored as a Commander with Star of the Royal Norwegian Order of St. Olav for his work that helped society. Næss also ran as a minor candidate for the Norwegian Green Party in 2005.

Næss died on January 12, 2009, at the age of 96.

Philosophy

Næss's book Erkenntnis und wissenschaftliches Verhalten (1936) introduced ideas that later became important in analytic philosophy after World War II.

In the 21st century, newer generations of philosophers recognized Næss as a pioneer of experimental philosophy, a term he used himself. One of his early works on this topic was “Truth” as Conceived by Those Who Are Not Professional Philosophers (1938).

Næss’s major philosophical work from the 1950s was Interpretation and Preciseness (1953). This book applied set theory to problems in language interpretation, building on the work of scholars like Charles Kay Ogden in The Meaning of Meaning. A simple explanation is that any word, phrase, or sentence can have many possible meanings, depending on language rules, the people involved, and the situation. These meanings can be broken down into smaller, more precise groups, which can themselves be divided further. This method helps show how language can be unclear, overly broad, or misleading, and it supports clearer communication.

Næss created a practical textbook, Communication and Argument: Elements of Applied Semantics (1966), that explained these ideas. The book became a key resource for teaching applied semantics, or "language logic," and was required for a philosophy exam at the University of Oslo, later called examen philosophicum.

In Communication and Argument (1966), Næss also shared his ideas about fair public debate. He suggested following these principles to keep discussions productive and respectful:
1. Avoid unfair references to unrelated topics, such as personal attacks or irrelevant arguments.
2. Avoid unfair summaries of others’ views, such as misquoting or taking statements out of context.
3. Avoid using unclear or vague statements intentionally.
4. Avoid falsely claiming that opponents hold views they do not.
5. Avoid sharing incomplete or false information, such as hiding important details.
6. Avoid using emotional appeals, such as sarcasm, exaggeration, or threats, to influence opinions.

These principles were part of a required philosophy course, examen philosophicum, in Norwegian universities for many years.

Later, argumentation theorist Erik Krabbe noted that Næss’s debate rules were early examples of guidelines used in the study of critical discussion.

Ecosophy T, which is different from deep ecology, was the name of Næss’s personal philosophy. Some scholars, like Warwick Fox, have linked deep ecology to Næss’s beliefs. The "T" in ecosophy T refers to Tvergastein, a mountain hut where Næss wrote many of his books. He believed everyone should develop their own philosophy.

Næss’s ecosophy focused on self-realization. He believed all living things—humans, animals, and plants—have an equal right to live and thrive. He argued that humans can become part of Earth’s ecosystems through self-realization, rather than focusing only on themselves. He stated that if people cannot predict how their actions affect others, they should avoid taking action.

In a summary of Næss’s career, Nina Witoszek noted that he often used the phrase "in principle" to soften his strongest ideas. He also acknowledged that practical actions often differ from ideal principles, and that compromises are sometimes necessary.

Selected works

• Næss, Arne (1936). Erkenntnis und wissenschaftliches Verhalten. Skrifter utg. av det Norske videnskaps-akademi i Oslo. 2. Hist.-filos. klasse, 1936 (in German). Vol. 1. Oslo: I kommisjom hos J. Dybwad. OCLC 5916296.
• Næss, Arne (1938). “Truth” as Conceived by Those Who Are Not Professional Philosophers. Skrifter utg. av det Norske videnskaps-akademi i Oslo, II. Hist.-filos. klasse, 1938, no. 4. Oslo: I. kommisjon hos J. Dybwad. OCLC 1021167.
• Næss, Arne (1953). Interpretation and Preciseness: A Contribution to the Theory of Communication. Skrifter utg. av det Norske videnskaps-akademi i Oslo. 2. Hist.-filos. klasse, 1953, no. 1. Oslo: I kommisjon hos J. Dybwad. OCLC 3195596.
• Næss, Arne; Christophersen, Jens A.; Kvalø, Kjell (1956). Democracy, Ideology, and Objectivity: Studies in the Semantics and Cognitive Analysis of Ideological Controversy. Oslo: Published for the Norwegian Research Council for Science and the Humanities by University Press. OCLC 1942421.
• Næss, Arne (June 1958). “A systematization of Gandhian ethics of conflict resolution”. Journal of Conflict Resolution. 2 (2): 140–155. doi: 10.1177/002200275800200202. JSTOR 172972. S2CID 144823357.
• Næss, Arne (1965). Gandhi and the Nuclear Age. Totowa, NJ: Bedminster Press. OCLC 368861.
• Næss, Arne (1966). Communication and Argument: Elements of Applied Semantics. Translated by Alastair Hannay. Totowa, NJ: Bedminster Press. OCLC 1012411.
• Næss, Arne (1968) [1965]. Four Modern Philosophers: Carnap, Wittgenstein, Heidegger, Sartre. Translated by Alastair Hannay. Chicago: University of Chicago Press. OCLC 252616. Translation of Moderne filosofer.
• Næss, Arne (1968). Scepticism. International Library of Philosophy and Scientific Method. New York: Humanities Press. ISBN 9780710036391. OCLC 1283.
• Næss, Arne (1973). “The shallow and the deep, long-range ecology movement: a summary” (PDF). Inquiry: An Interdisciplinary Journal of Philosophy. 16 (1–4): 95–100. doi: 10.1080/00201747308601682. S2CID 52207763.
• Næss, Arne (1975) [1972]. Freedom, Emotion and Self-Subsistence: The Structure of a Central Part of Spinoza's Ethics. Filosofiske problemer. Vol. 42. Oslo: Universitetsforl. ISBN 8200014592. OCLC 3841538.
• Næss, Arne (Fall 1984). “A defence of the deep ecology movement”. Environmental Ethics. 6 (3): 265–270. Bibcode: 1984EnEth…6..265N. doi: 10.5840/enviroethics19846330.
• Næss, Arne (Winter 1986). “The deep ecological movement: some philosophical aspects”. Philosophical Inquiry. 8 (1/2): 10–31. doi: 10.5840/philinquiry198681/22.
• Naess, Arne (1987). “Self-realization: an ecological approach to being in the world”. The Trumpeter. 4 (3): 35–42.
• Næss, Arne (1989) [1976]. Ecology, Community and Lifestyle: Outline of an Ecosophy. Translated by David Rothenberg. Cambridge, UK; New York: Cambridge University Press. doi: 10.1017/CBO9780511525599. ISBN 0521344069. OCLC 17621528. “Not a direct translation of Arne Naess' 1976 work, Økologi, samfunn, og livsstil, but rather a new work in English, based on the Norwegian, with many sections revised and rewritten by Professor Naess.”
• Rothenberg, David; Næss, Arne (1993). Is It Painful to Think?: Conversations with Arne Næss. Minneapolis: University of Minnesota Press. ISBN 0816621519. JSTOR 10.5749/j.ctt