Griffith was raised on a sheep property in central New South Wales.^[4] He was educated at Tudor House School, New South Wales, and the Geelong Grammar School, Victoria, in 1965 completing the NSW Higher School Leaving Certificate with first class honours in biology.^[5] He began a science degree at the University of New England, in northern New South Wales, and completed his Bachelor of Science degree in zoology at the University of Sydney in 1971.^{[6]: 528 [7]}

Griffith first became known for his search for surviving Tasmanian tigers, or thylacines,^[8] the last known specimen of which had died in captivity in 1936. The search was conducted from 1967 to 1973.^[9] It is considered the most intensive search to that point,^[8] and included exhaustive surveys along Tasmania's west coast,^[9] installation of automatic camera stations, prompt investigations of claimed sightings,^[10] and in 1972 the creation of the Thylacine Expeditionary Research Team with Bob Brown. It concluded without finding any evidence of the animal's continuing existence, despite numerous claimed ongoing sightings.^[8] Griffith's search was the subject of an episode of ABC TV's A Big Country;^[11] and his report of the search was published in Natural History.^[9][12]

The thylacine was declared extinct by the International Union for Conservation of Nature in 1982^[13] and by the Tasmanian government in 1986.^[10]

Griffith began writing on the human condition in 1975. His books seek to give a biological and rational explanation of human behaviour^[4] and include references to philosophical and religious sources.^[3]

His first book on the subject, Free: The End of the Human Condition, was published in 1988,^[14] and Griffith was interviewed by Caroline Jones on her Radio National program, The Search for Meaning.^[15][16] A Species In Denial (2003) became a bestseller in Australia and New Zealand.^[17] 'Freedom': The End of the Human Condition (2016) has been described as the definitive presentation of his treatise.^[18][19]

Griffith presents a wide-ranging induction-derived synthesis.^[18] In support of his theory, he cites from a broad selection of sources, including many thinkers he regards as "unevasive" or "contemporary prophets", including James Darling, Charles Darwin, Sigmund Freud, Carl Jung, Thomas Huxley, Stephen Hawking and Laurens van der Post.^[4][6]

Griffith explains human nature (what he terms the human condition) by proposing that as consciousness emerged in our hominid ancestors, the intellect's experiments in self-management were in effect criticised by our pre-established instincts, the result of which was that humans unavoidably became increasingly "angry, egocentric and alienated".^[20][21] An article by Griffith published in The Irish Times summarised the thesis presented in Freedom: The End of The Human Condition (2016) as "Adam & Eve without the guilt: explaining our battle between instinct and intellect."^[22] Kirkus Reviews wrote, "Griffith offers a treatise about the true nature of humanity and about overcoming anxieties about the world".^[23]

According to psychologist Ronald Conway, Griffith holds that we are at war with our own selves, causing humanity to become, as Plato proposed in his allegory of the cave, alienated from its original peaceful state of innocence. Griffith says that this war within is the cause of ongoing actual wars and the general lack of cooperation in the world.^[24] Griffith analyses the scientific literature in human evolution; rejects claims that human ancestors were brutal and aggressive; and instead points to fossil evidence such as that of Ardipithecus ramidus in support of his thesis that ancient humans were a gentle, loving and co-operative species.^[2]

Griffith's ideas have been criticised based on perceived problems with the empirical veracity of his anthropological writings, an objection that highlights his reliance on the writings of the South African novelist Sir Laurens van der Post and the work of the anthropologist Elizabeth Marshall Thomas.^[2] While readers may agree with the broad thrust of Griffith's thesis, some may also disagree with his evaluation of certain people and events, for example his "high opinion" of the Scottish psychiatrist R. D. Laing.^[25]

A reviewer of Griffith's 2003 book A Species in Denial described the book's thesis as "humanity is in denial about the loss of its innocence in a corrupt and broken world", and believed it would have benefited from including discussion of the works of Martin Buber, H. Richard Niebuhr, Lawrence Kohlberg and James W. Fowler, who also examine the moral stages of human growth.^[26]

Some reviewers described A Species in Denial as challenging^[27] or difficult to read, however "through the repetition of his concepts the reader finally grasps Griffith's meaning and, surprisingly, when this happens all kinds of questions arise, which is refreshing."^[28] Ronald Conway wrote "A Species In Denial needs repeated reading, not because it is particularly difficult but because it goes against so much of the resigned don't-rock-the-boat attitude of the Western mind in particular."^[24]

The Templeton Prize winner and biologist Charles Birch, the New Zealand zoologist John Morton, the former president of the Canadian Psychiatric Association Harry Prosen, and Australian Everest mountaineer Tim Macartney-Snape^[29][21][20] have been long-standing proponents of Griffith's ideas. Birch wrote the Foreword to Griffith's 2004 book A Species In Denial.^[6] Morton commended several of Griffith's books.^[30][31] In 2021 Prosen wrote, "Griffith puts forward a wide-ranging induction-derived synthesis. As Professor Scott Churchill, former Chair of Psychology at the University of Dallas, said in his review of Freedom, 'Griffith's perspective comes to us not as a simple opinion of one man, but rather as an inductive conclusion drawn from sifting through volumes of data representing what scientists have discovered.' ... I have no doubt Griffith's explanation of the human condition is the holy grail of insight we have sought for the psychological rehabilitation of the human race".^[18]

In a 2020 article "The fury of the left, explained", published in The Spectator Australia, Griffith argues that the ideology of the Left is dangerous to humanity's progress. He describes left-wing views as regressive and likely to lead to extinction:^[32]

So that is the first left-wing-culture-destroying clarification that understanding the human condition enables – that while the right-wing has continued humanity's heroic quest for understanding, the Left has given in to the temptation of relief-hunting^[a] and abandoned that all-important search [for understanding of the human condition].

 ... the Left have not only given up the search for understanding, they are actively working against the finding of it. This is because their favoured feel-good cause of dogmatically insisting that everyone comply with PC, Marxist cooperative and selfless principles oppresses the freedom of expression needed to find knowledge, ultimately the understanding of ourselves that alone can end our insecure condition and actually bring about a cooperative and loving world.

When interviewed by Alan Jones and Graham Richardson on their Richo & Jones Sky News Australia television programme, Griffith said that "my article in The Spectator last week was all about how we can bring rationale, understanding to the danger of the Left, reason versus dogma".^[33]

Dutch actor Pierre Bokma discussed Griffith's work on the Zomergasten television programme for VPRO in 2024, saying Griffith's explanation allowed him to understand why humans are ultimately good despite being angry, guilty, alienated, selfish, egotistic and power hungry.^[34]

In 2025 Macartney-Snape wrote that Griffith had answered what John Kenneth Galbraith referred to as "the search for a truly superior moral justification for selfishness".^[21]

The World Transformation Movement was founded by Griffith in 1983 as the Centre for Humanity's Adulthood, an organisation dedicated to developing and promoting understanding of the human condition. It was incorporated in 1990 with Griffith and his colleague, mountaineer Tim Macartney-Snape, among its founding directors and became a registered charity in New South Wales in 1990, known as the Foundation for Humanity's Adulthood. In 2009, its name changed to the World Transformation Movement.^[35]

In 1995, Griffith, Macartney-Snape and the Foundation for Humanity's Adulthood (the World Transformation Movement's name at the time) were the subject of an Australian Broadcasting Corporation (ABC) Four Corners programme^[19] and an article in the Sydney Morning Herald (SMH) newspaper^[36] in which it was alleged that Macartney-Snape used speaking appearances at schools to promote the foundation, and that Griffith "publishes work of such a poor standard that it has no support at all from the scientific community". In defamation actions against the ABC and the SMH, the allegations were ruled to be false and the pieces defamatory.^[37]

In 1998, following a complaint by Griffith and Macartney-Snape, the Australian Broadcasting Authority censured the ABC for unbalanced and inaccurate reporting and breaching the ABC code of practice, with The Bulletin describing the Four Corners programme as a "hatchet job" (another term for a "hit piece").^[4]

Griffith, Macartney-Snape and the World Transformation Movement sued the ABC and the Sydney Morning Herald in the NSW Supreme Court and both publications were found to be defamatory.^[36][38] In 2008, the ABC was ordered to pay Macartney-Snape almost $500,000 in damages, and with costs, the payout was expected to exceed $1 million.^[38] While the jury found that what the ABC said about Griffith was defamatory, the judge dismissed the case after the defences of truth, qualified privilege and comment were considered.^[37][38] Griffith appealed that decision to the New South Wales Court of Appeal, which dismissed the appeal^[39] on the basis of qualified privilege and comment being upheld, but found that the defamatory allegation about Griffith was not justified.^[19][37][40] The court case against the Sydney Morning Herald was resolved in 2009 when it published an apology to the World Transformation Movement for the harm caused by the publication.^[41]

In 2020, an article by Griffith published in The Spectator Australia under the heading "The science of bushfires is settled"^[42] about his biological analysis of the dangers of eucalypts in light of the 2019–20 Australian bushfire season resulted in him appearing on Alan Jones's 2GB radio programme,^[43] and on the Richo & Jones Sky News Australia television programme.^[44] Griffith's analysis also generated interest in the United Kingdom.^[42] In a follow-up Spectator Australia article, Griffith makes a link between what – in his view – is poor forest management and left-wing influence – their outlook on such issues arising, as he sees it, from the human condition:^[32]

So the management of our forests comes down to how to combat the irrational "religious" fanaticism of tree-hugging Lefties. Indeed, everywhere we look in the world we are faced with this problem of "how to combat the irrationality of the increasingly rabid Marxist, politically correct culture?"

Well, if honest biological thinking was able to get to the bottom of the problem of eucalypts ... might such thinking also be able to finally solve the problem of the madness of the Left? I believe it can.

 ... when we humans take up a cause that makes us feel good it can bring such astronomical relief to the extreme insecurity caused by our species' tortured, 'good and evil' – stricken so-called human condition that our attachment to that cause becomes more precious to us than any rational argument Plato, Darwin and Einstein combined could put to us! ...

 ... So it's relief from the human condition at all costs that is really going on. The human condition is the real issue ...

• Death by Dogma: The Biological Reason Why the Left Is Leading Us to Extinction, and the Solution. WTM Publishing & Communications Pty Ltd. 2021. ISBN 978-1-74129-066-0.
• Freedom: The End of The Human Condition. WTM Publishing & Communications Pty Ltd. 2016. ISBN 978-1-74129-028-8.
• The Book of Real Answers to Everything!. WTM Publishing & Communications Pty Ltd. 2011. ISBN 978-1-74129-007-3.
• A Species in Denial. WTM Publishing & Communications Pty Ltd. 2003. ISBN 978-1-74129-001-1.
• Beyond the Human Condition. WTM Publishing & Communications Pty Ltd. 1991. ISBN 978-0-646-03994-7.
• Free: The End of the Human Condition. WTM Publishing & Communications Pty Ltd. 1988. ISBN 0-7316-0495-4.

• THE Interview. WTM Publishing & Communications Pty Ltd. 2020. ISBN 978-1-74129-056-1.
• Transform Your Life and Save the World: Through Living in Support of The Biological Truth About the Human Condition. WTM Publishing & Communications Pty Ltd. 2016. ISBN 978-1-74129-035-6.