Peter Medawar, the British immunologist, claimed this to be man’s most
successful technique for understanding the world. Unfortunately there are
parts of the world we would like to understand very much, to which scientific
techniques, in practice, cannot easily be applied. They include political
problems, for which we all use a much less successful technique. It is to
choose a hypothesis, search for and quote any data that support it and
rubbish any that do not. Formal debates, and court cases, for example, are
conducted in this way. I once heard a professor complain that department
heads never discussed anything at faculty meetings, they only thumped the
table. This seems as useful a description as any. Let us call those who
argue this way ‘thumpers’, in contrast to scientists who, at least when
behaving themselves, are ‘popperists’.

Two thumpers, when arguing, throw data at each other like snowballs.
The winner at snowballing is usually the one who scores the most hits, or
does not run out of ammunition. Either way, it is not a quick route to understanding
the problem. We all know of arguments first encountered in our teens, still
unresolved by thumping. How many of us have friends with whom we have thumped
for years without changing our views?

Despite their different track records, the two techniques have similarities
and it can be hard to tell whether arguers are thumping or ‘poppering’.
In both cases the two sides state their position and bring forward supporting
evidence. But the underlying intentions are different. Thumpers are what
my dictionary calls ‘eristic’ (‘of argument or arguer, aiming at victory
rather than truth’). One sign of thumping can be the generation of heat.
Another is moving to a new line when losing. ‘Well, all right then, what
about Yasser Arafat?’ The acid test is whether the arguers are trying to
frame efficient questions and search out the data that will answer them.

We might get answers faster if we could approach some of our ecological
problems in a more poppering way. An example is the problem of ‘sustainable
economic growth’, a declared aim of almost every politician in the world
and probably the great majority of its inhabitants. Few people believe we
can grow richer forever. The second law of thermodynamics and the increase
of entropy tell us that; and anyway it is intuitively obvious that the ecosphere
will not be stable if one species tries to appropriate a perpetually growing
share of its finite resources.

But when politicians speak of sustainable growth, they don’t mean sustainable
for ever. They have a much shorter time-scale in mind. Understandably, in
democracies, they may not be looking beyond the next general election. Crispin
Tickell, Britain’s former ambassador to the UN and one of the organisers
of the Earth Summit in Rio in 1992, recently put their horizon at ‘the end
of the month, or even the end of the week’. Any country can hope to sustain
growth for this long. So the sustainable growth problem comes down to a
question of timing. Even if growth does have to stop one day, need we worry
now? Is that day still a long way off? Are there any more important problems
than this? Cancer is almost trivial by comparison. It is a lot to ask that
we should approach such a profound issue with open minds, but unless we
do, we may find it hard to frame, and answer, efficient questions.

We can hardly hope to solve the growth problem with one brilliantly
conceived set of data. For example, Lester Brown, the doomster from the
Worldwatch Institute in Washington, estimated in 1980 that a subsistence
diet for one person needed 0.21 hectare, and that the world’s agricultural
land averaged 0.38 hectare per head. These figures are chilling enough,
given the predicted doubling of the population in the 21st century. But
cornucopians would never accept that the figure of 0.21 hectare cannot be
reduced by improved technology.

The question that sounds efficient, ‘How long will our nonrenewable
resources last?’, doesn’t seem to work well. We find new reserves as well
as using up old ones. The leading American cornucopian Julian Simon has
even argued that the most reliable single indicator of a resource’s availability
is its price, and that on this criterion most of our important resources
are more available now than before. This may be true in the short term,
but how many of us have the optimism needed to believe that finite resources
can be consumed at an exponentially increasing rate, yet at the same time
become more abundant?

In contrast, conservation luminaries including Paul and Anne Ehrlich,
and Peter Vitousek of Stanford University, undertook a huge trawl for data,
trying to estimate how much material is produced by photosynthesis and
the fraction of it used by man. They found the total net production (photosynthesis
by plants less their respiration) to be 224.5 billion tonnes of dry organic
matter per year. Humans and their livestock were estimated to consume directly,
as food and wood, 7.2 billion tonnes, about 3 per cent of the total.

But human beings indirectly affect the availability of food, for example
by paving over agricultural land. This reduces the food available for the
rest of the biosphere, just as much as if they eat it directly. When these
indirect effects were included, such as the destruction of the parts of
crops not eaten, converting forest to pasture, clearing land by fires, desertification
and overuse, the estimate was that 25 per cent of the total potential production,
and nearly 40 per cent of the potential terrestrial production, was being
appropriated by humans.

The authors recognise the difficulty of getting reliable data for such
a survey. They could not attach confidence limits to their figures. Sometimes
estimates by different workers varied seriously (for example 1.74, 2.8 and
5 billion tonnes for consumption by livestock) and the authors had to use
an average or adjudicate between workers. Nevertheless the authors claimed
that: ‘our results indicate that with current patterns of exploitation,
distribution and consumption, a substantially larger human population could
not be supported without co-opting considerably well over half of terrestrial
net production. Observers. . . who believe that limits to growth are so
distant as to be of no consequence for today’s decision-makers appear unaware
of these biological realities’. Perhaps we are still looking for the really
efficient questions. Suggestions on a postcard please.

Peter Holway is a retired schoolmaster living in the Isle of Wight

This little scenario neatly reflects our attitude to the environment.
Faced with dwindling natural resources and imminent global disaster, we
seem unable to turn off the tap.

The reason why we have a crisis now, and not 100 years ago, is that
we are now consuming more. We are doing this because there are more of
us, and because we are richer. These trends are continuing. In another 60
years the world population will have at least doubled, and economic growth
at a probable 2 per cent a year will have nearly quadrupled our per capita
income. Since our consumption is the product of these two factors, we may
be heading for something like an eightfold increase in consumption in the
next 60 years.

Despite all this, some of us still doubt that we have anything to worry
about. Others respond by recycling glass and paper, using low-energy light
bulbs and alternatives to peat, restricting the use of cars and all the
other commendable green practices. These measures may reduce our consumption
by 10 per cent or so; as an answer to a possible increase of 800 per cent,
they amount to no more than mopping up some of the water. To turn off the
tap, we have to face up to the problems of both population growth and economic
growth. It would be no solution to stabilise the population and allow the
standard of living to continue climbing. Doubling the standard of living
would damage the environment just as surely as doubling the population.

Economic growth is the more difficult issue of the two in many ways.
For one thing, almost no one outside the green movement shares the aim of
stopping growth. For another, there is poverty as well as affluence in the
world; we need to find ways of stopping economic growth not for everyone,
but just for those who already have everything they need.

We are handicapped in our attempts to find a solution because we can
only guess two key quantities. The first is the maximum sustainable consumption
(and consequent production of waste) that the Earth can accommodate, and
every possible answer has its adherents. There are cornucopians who believe
that for practical purposes the Earth’s resources are infinite. The Brundtland
Report, which laid the foundation of the summit in Rio, envisaged an increase
of between five and tenfold in economic activity in 50 years without apparent
alarm. Green campaigners are more pessimistic; some have been shown to be
unduly so. But no one doubts that our forests are shrinking, cropland is
becoming desert, species are disappearing, the concentration of ozone is
falling and of greenhouse gases is rising, and there is damage from acid
rain. Every one of these situations is getting worse. Such a person would
indeed be an optimist, who was certain that we were not close to the limit.

The second quantity we do not know is the level of consumption that
provides all basic necessities and enough security and leisure to allow
a reasonable cultural life. In the roundest figures, we now have about a
billion people in the developed world whose living standard is some 15 times
that of the four billion in the Third World. For brevity, let us call these
the rich and the poor. Taking as our unit the consumption of a billion poor
in a year, the world’s consumption today is therefore 4 units by the poor
and 15 by the rich.

Clearly the poor are below the acceptable minimum level and the rich
above it, so the figure we are aiming at is between 1 and 15 units per billion
people. Those of us on average earnings in Britain in the 1950s, when our
living standard was half of today’s, will perhaps remember that we did not
consider ourselves as having to go without anything essential. This puts
our minimum between 1 and 7. There are horrendous simplifications here,
but what follows if we guess the minimum as 4 units per billion? By the
time the living standard of the poor is quadrupled, their numbers will have
at least doubled, so their consumption would rise to 32 units (8 billion
at 4 units per billion). So even if the rich stay still, total consumption
would be 47 units – two-and-a-half times the present figure. It suggests
that to achieve a stable society, living standards of the most affluent
may need to be not just held level, but reduced.

The idea of stopping economic growth will be difficult to sell. Deep
changes in our ways of thinking are needed. We will need to replace terms
such as ‘growth’, ‘development’ and ‘wealth creation’, which sound positive
and progressive, with terms that more accurately describe the consumption
of our finite resources. Possessions must not confer status; indeed, any
unnecessary, conspicuous consumption is to be regarded as criminal.

Some propose financial carrots and sticks, such as green taxes, tradeable
permits and the ‘polluter pays’ principle. The difficulty here is that our
problems spring from our following our short-term material interest. But
apart from these difficulties of individual attitudes, we face the large-scale
problem, in Europe, of an economic system that breaks down without growth.
We see this today in Britain. Our material living standard, having risen
steadily since 1945, has halted. It is, within a few per cent, as high as
it has ever been. But our free-market capitalism cannot work without growth,
so we cannot share out either the work or the wealth in a sane way, and
we have more than three million without work, beggars on the streets, even
a falling expectation of life among the worse-off. We need a new model
of economics.

However, there is no point in emphasising how difficult it will be to
reduce consumption by the affluent. We cannot achieve a stable society on
a finite planet on the present principle of all consuming as much as we
can. Reducing consumption is the only way forward. There is no alternative
to turning that tap off.

Peter Holway is a retired schoolteacher living on the Isle of Wight.