A Classic Waste Of Breath

An argument that a thing is natural, therefore not a cause of concern, is used greatly in modern times, most especially in connection with the arguments over whether or not we puny humans can interfere with natural environmental cycles.  Such arguments can look good on the face of things.

The naturalistic argument goes back at least to Ancient Greece. 

In the art of misleading an audience with a seemingly open-and-shut case it really is a classic.

" It may be that there are some who would decry the importance of the rules of natural justice. ......those who take this view do not, I think, do themselves justice. As everybody who has anything to do with the law well knows, the path of the law is strewn with examples of open and shut cases which, somehow, were not: of unanswerable charges which, in the event, were completely answered ; with inexplainable conduct which was fully explained; ...
nor are those with any knowledge of human nature who pause to think for a moment likely to underestimate the feelings of resentment of those who find there is a decison against them being made without their being afforded any opportunity to influence the course of events."

Megarry J
John v Rees [1970] Ch 345, 402

Carbon dioxide is perfectly natural

“Carbon dioxide is not a pollutant. Every time you exhale, you exhale air that has 4 percent carbon dioxide. To say that that’s a pollutant just boggles my mind. What used to be science has turned into a cult.”
William Happer

That sounds reasonable enough, on the face of it.  However, super facie - on the face - is a classic kind of argument which "proves" a valid point only if we fail to dig beneath the surface.  William Happer's argument about CO2 is a naturalistic fallacy - the argument in false logic that a thing is beneficial or good just because it is natural. 

Let us dig down a bit.

If CO2 is not a pollutant because we exhale 4%, then oxygen is not a pollutant because we inhale it as 21% of air.  If what we get rid of is not a pollutant, then what our lungs absorb naturally, oxygen, must be even less of a pollutant.

What does 'pollutant' mean?  Here is a proposed scientific definition.


any substance in such a chemical or physical form and / or quantity as to alter the physical, chemical or biological properties of an environment in a manner adverse to at least one class of its living inhabitants.

Any and every living thing is killed by any and every substance.  It is merely a matter of environmental percentages and uptake.

Water is essential to human life.   But we may drown in a few inches of it.

Oxygen is essential to human life.   But we may die in a surfeit of it.
The lungs, the eyes, and, under certain conditions, the central nervous system are the organs most affected by prolonged exposure to hyperoxic environments. Free radical formation during cellular metabolism under hyperoxic conditions is recognized as the biochemical basis of oxygen injury to cells and organs.

In a pure oxygen atmosphere, we are, and everything around us is, at great risk of combustion from a small spark, as witness the tragic loss of the Apollo 1 crew.

All things in moderation

An excess of any food, nutrient or environmental benefit is lethal - it is just a question of how much is too much.

For every substance that is essential to a specific living thing, there are upper and lower limits outside of which the thing specified cannot live.

For every substance that is lethal to a specific living thing, there is a lower limit inside of which the thing can live.

For every substance that is beneficial but non-essential to a specific living thing, there is an upper limit outside of which the thing cannot live.

These lethal limits apply to all creatures, all plants, all living things.

To a human, CO2 is a pollutant.  That is why we breathe out more CO2 than we breathe in
To us, CO2 is a suffocant: if the air contains too much CO2, we die.

CO2 in the past

As to atmospheric CO2, there is another naturalistic, superficial argument - that in the age of dinosaurs CO2 levels were much higher than today but living things thrived.  Now, in that era the plants were different.  It is possible that humans could live in such an environment.  But it is exceedingly implausible that our crops and livestock could.  We would starve.


There are many gases in the atmosphere.  Humans have been breathing them in and out since the first human made the first footprint. 

If all of the gases in the atmosphere are natural, does it not follow that ratios are immaterial?  After all, any mixture of purely natural things is itself a purely natural thing.

On accepting that atmospheric CO2 is natural, hence not a problem, must one also accept that a like quantity of any other natural atmospheric gas is natural, and hence not a problem?

Resource / further study:

The Earth-Atmosphere System