| If you were
to measure 20 carrots, and found that they were all between
six and eight inches long, you might conclude that all
carrots were in that size range. The manner of logic you used
to draw your conclusion is called inductive reasoning.
According to the philosopher John Stuart Mill, its chief
proponent, we are using inductive reasoning when we conclude
"that what is true of certain individuals of a class,
is true of the whole class, or what is true at a
certain time will be true in similar circumstances at all
times."
He argued that this logic is possible because
there is a certain "uniformity" in nature which allows for
such conclusions to be made. The classical example used to
illustrate inductive reasoning is the "fact" that all
human beings are mortal. To prove this "fact," however,
all human beings would have to be dead already.
Obviously, some of us are still around! How can we be sure
that one of us won't live forever? We can't. However, through
inductive reasoning, we can conclude that there is an
extremely high probability that all human beings are
mortal.
Many scientific "laws" are a result of
inductive reasoning – even though it is, a matter of
probability. Astronomer Johannes Kepler, for instance, noted
the position of the planet Mars during several points of its
orbit. Working on the assumption that natural orbits maintain
a uniform geometry, he induced that the orbit had to be in the
shape of an ellipse. In fact, if you were to actually
calculate the planet's position during ALL of the points of
its orbit, it would, in fact, trace an almost perfect ellipse.
No one has ever discovered a planet that didn't follow his
principle, which has become known as "Kepler's Law" of
planetary orbit.
No one has discovered an exception so
far, that is. As the study of the universe expands, we
cannot know with certainty what we will encounter. Other
scientific "facts," drawn from inductive logic, have crumbled
as a new piece of evidence was found. The weakness with
inductive reasoning, then, is that it relies on partial
knowledge to draw conclusions about "truth." In the case of
medical science, this weakness can be harmful, if not tragic.
When medical researchers draw their conclusions on what is
right for ALL people based on what they have observed to be
right for SOME people, they run the risk of doing irreparable
harm to many people. |
Take the
example of appendectomies. Medical doctors had studied this
curious organ for a long time and had never found a useful
purpose for it. They concluded therefore, that it had
no useful purpose. When it became inflamed or otherwise
troublesome, they removed it. It took years for the medical
profession to admit that its reasoning was incorrect, and to
seek other means of treating appendicitis.
Medical science still stands by most of its
other conclusions, however, even though they were arrived at
by the same reliance on inductive reasoning. Moreover, it
adheres to the "rules" with a rigidity that often does not
allow for individual differences. Scientists discovered that
the average temperature for a human being is 98.6 degrees
Fahrenheit. If you have a 99.3 degree temperature, you're said
to be "running a fever" and you're given medications to bring
the temperature back to "normal."
The problem with this type of reasoning is
obvious. No one perfectly fits the profile of the "average"
human being – not in height, weight, or even body temperature.
It is incorrect to conclude that the correct temperature for
all members of the human race is the same as the "average"
temperature of a sample of individual members.
Long ago, clothing manufacturers realized that
all people are different. They would love it if all size
people were exactly the same. They wouldn't have to produce a
size 12 petite as well as a size 12 tall, medium, and large.
Even so, it seems impossible at times to find something that
fits right! The only way to get a really good fit is to have
the item custom-made.
If you go to a tailor and order a new outfit,
someone takes your exact measurements. Can you imagine the
tailor saying, "The average human being is 5'7" tall, 180
pounds, with a 34" inseam. I'll use those measurements to make
your wardrobe?" You would, no doubt, look for a new tailor.
Yet, because of the total reliance on
inductive reasoning, science – particularly medical science –
uses "off-the-rack" diagnoses, remedies, and medications. They
routinely begin to stitch a wardrobe together using only
"average" measurements. Is it any wonder, then, that their
suits seldom fit
right? |