Rationality: not a strong trait in humans

The hole in the ozone layer that was caused by the release of CFCs, climate change, ocean acidification, ocean warming, sea level rise, the air pollution from the burning of fossil fuels that kills millions of people world-wide each year and many other problems have shown that humanity has great power to change our environment and the Earth's systems. Our failure to respond appropriately to most of these, in spite of knowing that inaction will be disastrous, is just one demonstration that we are largely irrational beings.

This page was started 2009/06/02 and last edited 2022/08/02
Contact: David K. Clarke – ©


Many human traits are manifestly irrational...
  • Poker machines are designed to make money for their owners and for the owners of the premises that house the machines; it is absolutely impossible for regular players to do anything other than loose a substantial part of the money that they put into the machines; yet there are many who love to 'play' the pokies. Playing poker machines makes as much sense as taking money from your bank account and burning every fifth note.
  • One needs only observe the traffic on any road to see irrational behaviour; few people drive in a way that is efficient in fuel use, conservative in wear on their vehicle and its components, and maximises safety. Young men, in particular, often drive with the subconscious aim of achieving adrenalin rushes.
  • Our use of tobacco and many illicit drugs is harmful to our health, often damaging to society, and produces no net benefits to anyone (apart from the tobacco companies and organised crime).
  • Economists and governments refuse to recognise that growth cannot continue for ever; both believe that the economy must grow if a nation is to be 'successful'. A growing economy generally means increasing greenhouse emissions, a growing amount of consumption, a growing rate of depletion of natural resources and a growing amount of waste being dumped in rivers, oceans and landfills. This is plainly not sustainable.
  • Religion is perhaps the most widespread and important human irrationality; the majority of the world's people subscribe to one or another conflicting and disparate set of beliefs on which they largely base their lives, but for the veracity of which there is absolutely no evidence.
The great pity is that humans have, by our science and technology – and in spite of this streak or irrationality, become very powerful. We have, by our mining and burning of fossil fuels, clearing of forests and other practices, changed the composition of 'our' planet's atmosphere to the point where the climate is changing and the oceans are becoming uncomfortably acidic for many of the organisms that live in them. This is all generally disadvantageous to, not only ourselves, but to many other species.



Why are the great majority of people unwilling to take action while our governments allow climate change, ocean acidification, sea level rise and the air pollution from the burning of fossil fuels that kills millions of people world wide each year to gradually destroy the world that we know and love?

It seems to be due to some basic flaw in human nature.

A very small part of the answer to climate change and related problems; Peterborough Solar Farm, South Australia
Peterborough Solar Farm
The world could and should, with great urgency, change from fossil fuels to renewable energy such as solar and wind. It is quite possible, is being done, but the urgency is missing!

It is ironic that many of us can be sufficiently intelligent to see this, to be able to understand the ways in which the Earth is changing, the consequences of our actions and our inactions, but not have the rationality needed to make the necessary changes to our behaviours. Is it that some of us are rational, but many are not; some are governed by their intelligence, others largely by emotions; some of us are selfish and others altruistic?

Our greatest irrationalities seem often to be associated with short-sighted thinking. Climate change is a long-term threat, driving (rather than walking or riding a bicycle) to the shop is a short-term activity. We seem unable, individually or collectively, to change our short-term behaviour for the sake of our long-term survival. Many of our day-to-day activities need to change for us to control climate change.

Our use of antibiotics is another example of short-sited thinking harming our long-term welfare. Our farmers feed antibiotics to their animals because it slightly increases the growth rates – at the same time as training bacteria to live successfully in the presence of antibiotics.

Intelligent life on Earth has been one of nature's greatest experiments in this wonderful Universe. It seems a shame that it appears to have failed because of an insufficiency of rationality.

A list of things that can be done to reduce greenhouse impact is given on another page; many of them would also save money. Why are we not doing them?

Added 2015/02/22

Are we sheep or rational beings?

As I write this the proposed execution of Andrew Chan and Myuran Sukumaran, the ringleaders of the so-called Bali Nine heroin trafficking group, is due to happen in Indonesia within the next few weeks. Just for the record, I'll say that I am opposed to the death penalty; it is very final, if a conviction is found to be an error there is no way of undoing an execution. I'll also say that the two may well have been rehabilitated and, if they were released, could prove to be useful members of society in the future.

But it is all a matter of proportion.

It has been a very convenient distraction for the Abbott Australian government. PM Abbott has done all he can to keep the coal industry alive and to hold back renewable energy development in Australia. His actions have locked in a higher level of climate change and related problems than was necessary and these developing global disasters will displace millions of people and cause the extinction of thousands of species.

Similarly, millions of people have been displaced and tens or hundreds of thousands killed in the Middle East, including especially Iraq, due at least in part to the meddling of Western nations, particularly the USA, UK and Australia.

But in mid to late February 2015 the Abbott government and the Australian people seem to care far more about the lives of two convicted drug smugglers in Indonesia than they do for these enormously bigger problems.

This section added 2019/12/15

Reacting emotionally rather than rationally

People often react emotionally rather than rationally to events that require thought and consideration rather than simple 'gut reactions'.

The opposition to a low-medium level radioactive waste repository in Australia seems to be due to an emotional fear of 'radioactivity'. I argue on another page that there is no rational justification for the opposition and the whole thing is a 'storm in a teacup'.

Edited 2013/07/15

Use of daylight

People function best in daylight; our eyes are much more poorly adapted to operating at night than are those of nocturnal animals. This being so, why do the great majority of people sleep during the first few hours of daylight and remain wakeful during quite a few hours of darkness in the evening? This is not an efficient use of the daylight hours; rather than waking around 0800 and going to bed about midnight it would seem to make much more sense to wake around 0400 and go to bed about 2000 – either way you can get the required eight hours of sleep.



People must be somehow 'hard-wired' to keep these irrational hours. I don't understand this behaviour, I've never read an explanation, and can't even guess why it is so common. I'd be interested to hear if someone has a reasonable explanation for it.
I live in an area with a long, hot summer (Mid-North South Australia). Many days in summer are hot enough so that most people try to avoid going out during the hottest part of the day. On these hot days I rise at or before daylight so that I can use the best part of the day; the period during morning twilight and the first few hours after sunrise when the temperatures are pleasant, or at least tolerable; but I see few others out and about then.

The evenings on these hot days are a little cooler than near the middle of the day, but of course temperatures typically decline from sunset until around sunrise of the next day, so the mornings are normally cooler than the evenings.

It is irrational to sleep during that part of the day that is most pleasant to be out, and then try to be active in some less pleasant part of the day. Surely we can all easily learn to go to bed and sleep earlier in the evening and then rise earlier too?


One of the basic principles, I believe, of 'biodynamic agriculture' is planting according to the phases of the Moon.

What effects does the Moon have on the Earth? The Moon provides some light at night and due to its gravitation it is the main cause of the tides (the Sun has a smaller effect on the tides). It is difficult to imagine how the Moon could significantly impact plant growth.

The light direct from the Sun is about 500,000 times as intense as the light from the full Moon. The quarter Moon provides no more than a quarter of the light of the full Moon. Compared to the light the Earth receives from the Sun, Moon light is negligible.

The tides are caused because the Moon's gravitational pull on the side of the Earth that is nearer to it is slightly greater than the pull on the far side of the Earth.

In regard to biodynamics, how powerful is the Moon's pull at the surface of the Earth compared to the Earth's own gravity? Gravitational force depends on the mass of the bodies involved and the distance from them. The Earth is about 81 times the mass of the Moon. A person standing on the surface of the Earth is about 6,400km from the centre of mass of the planet and about 380,000km from the centre of mass of the Moon.

The force of gravity is proportional to the product of the masses involved and inversely proportional to the square of the distances between the bodies. So the force of the Earth's gravity on someone standing on the surface of the planet relative to the force of the Moon's gravity would be proportional to 1 : 1 / (81 × (6,4002 / 380,0002)). This equals 1 : 0.0000035. Putting it another way, the Earth's gravitational pull on a plant would be about 286,000 times as great as the Moon's gravitational pull.

So in summary, the Moon's effects on a plant on the surface of the Earth could only come from the Moon's light (which would, on average, be much less 1/500,000th that of light from the Sun) and the Moon's gravitational pull (which would be 1/286,000th that of the Earth).

Given this, how could anyone place any credence in the theory that the phases of the Moon have a significant impact on plant growth?

Finally, if planting according to the phases of the Moon had significant effects on plant growth and success wouldn’t we find that they timed things like flowering, dropping leaves, dropping seed, etcetera to moon phase; but we don’t. It would be easy to demonstrate the link between plants growth and Moon phases scientifically, but where is the research confirming the theory?


Bruce Hood, in his book, 'Supersense: From Superstition to Religion – the Brain Science of Belief' makes the point that our brain's 'design' is such that the formation of beliefs not based on evidence can easily happen, especially early in our lives.

Michael Shermer has made statements along the same lines.

Related pages

External sites...

Dunning-Kruger effect

On this site...

Delusion should be more broadly defined than just its clinical meaning. For example, religion is delusional, any belief unsupported by evidence is delusional.

Humanity and fossil fuels; Man has behaved irrationally, rather like a population of single-celled organisms, in the way he has exploited fossil fuels.

Suicide as a rational decision

The absurdity of religion

Opposition to a low-medium level radioactive waste repository in Australia seems to be emotional rather than rational.