Why Think Twice?
You have probably heard the expression many times. "Think
twice" is a reminder to be careful about assuming that your
first conclusion is correct. Carpenters have a similar saying:
"measure twice, cut once," which is a habit that prevents
a lot of mistakes. Thinking twice does the the same thing in
many areas - it prevents errors. Getting familiar with some of
the common "thinking errors" also helps you avoid them,
so here is a look at one that trips up a lot of people.
Straight-Line Projections
When he first visited the ocean, a scientist noticed that
the water level getting higher. He carefully measured it for
a few hours, then noted that every hour it was going up a foot.
With his pen and paper, he quickly calculated that the ocean
would be 700 feet higher in less than a month, drowning most
of the major cities on Earth. In a year only the highest mountains
would be above sea level.
He ran off to sound the alarm and show his calculations to
others. Of course, they knew the ocean better than him. It came
up every day the people explained, but then it went down again
later. This was the tide, they explained, something he somehow
hadn't learned.
Do you think this silly story has no relevance to real science
and scientists, or your own errors? Think twice! This thinking
error can be found all over. For example, a cooling trend in
the 1970s had some scientists proclaiming that Florida would
be too cold to grow oranges by the 1980s. Today's more extreme
projections of global warming are probably based on the same
error (of course they could be wrong in either direction).
Here's a true story: In 1975, my very serious science teacher
showed us a very serious film which proved oil supplies would
be depleted in fifteen years. It is true that there was (and
is) just so much oil on the planet. It was also true that our
use of it was growing. The math showed we would clearly run out
soon.
But we didn't run out in 1990, nor in the seventeen years
since then, nor are we likely to in the next seventeen years.
"Scientific" projections like these often rely too
much on math and those lines on a graph. When other factors are
considered, they are often just used in ways that confirm the
theory that has already been established. The thinkers involved
may be very intelligent, but their thinking-error is in assuming
complex interactions can be reduced to simple formulas which
can then be used to make accurate predictions.
Let's look again at the example, and what was ignored. When
the price of oil rises, producers try to find more oil - a factor
apparently ignored in the projections. If these scientists had
thought twice, they may have easily stumbled upon the idea that
maybe we hadn't yet found all the oil out there - and that high
prices would make people want to find more.
Higher prices usually reduces demand as well. It's not hard
to imagine that people would use less gas if dwindling supplies
caused the price to go from 50 cents-per-gallon to $4 or even
$15. They apparently ignored this normal economic reality as
well.
High prices increase demand for alternative energy sources
too. It's reasonable to assume that many alternatives look attractive
when oil prices are ten times as high, right? And this means
there will be substitutes for oil long before it runs out. This
normal economic reaction was ignored. That "scientific"
film assumed that without government action we would just keep
using oil in the same way until one week it was gone. In hindsight,
it seems like the "science" of a child's mind.
Whether economic, biological, psychological, political, or
ecological, many systems are self-correcting to an extent. They
have trends which look like they'll continue to head in a given
direction, but other factors prevent this from continuing. This
isn't to say that things always return to some norm, or in a
statistician's terms, "revert to the mean." But in
most areas where we try to predict the future, the interactions
of the various factors are complex enough that we aren't likely
to have much success.
Wouldn't it be nice if predicting the future was as simple
as collecting data, making a graph or two, and assuming things
will continue in the same direction? A nice thought, perhaps,
but life is more complicated than straight-line projections can
account for. Collecting data and trying to make sense of it is
important, but before you think you see where the data is leading,
take a look at anything which might affect those predictions.
Think again.
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