You can be sure about things you have experienced for yourself. For
example, you know that water is wet and that fire burns. You know
what you had for breakfast (things in the past) and what you are
wearing (things in the present), though you cannot be sure about the
future. You also “know” far more things than your own experience
tells you—information you get from other people, such as parents
and teachers. But can you be sure it’s true?
CAN WE KNOW
ANYTHING
FOR SURE?
COMMON KNOWLEDGE
We possess a vast database of information that has been
built up over generations of human existence. It is passed on
in the stories parents tell their children, the books authors write, and
the records people leave behind them. More and more of this information
is being stored on the Internet. It is always growing and changing as
people make new discoveries that alter our ideas about the past or
reveal new facts about the world and the universe. Today, we know for
a certainty that Earth and the other planets orbit the Sun, but for thousands of
years, people believed the exact opposite— that the Sun circles around Earth.
After all, both Greek philosopher Aristotle (384–322 ), the greatest authority
of the ancient world, and the Bible, the Christian holy book,
said so, and they couldn’t be wrong, could they?
KNOWING AND BELIEVING
There is a difference between what we know for
a fact to be true and what we believe to be true.
Factual knowledge is based on eyewitness evidence
(either our own or that of other people), rational
explanation, and scientific proof. Belief is based
on the hope or confidence that something is true.
People of all religious faiths have no doubt that
their beliefs are the truth, but they cannot prove
for certain that God or the supernatural exists.
“KNOWLEDGE Is AN
uNENDING ADVENturE
At thE EDGE Of
uNCErtAINty.”
Jacob Bronowski (1908–1974),
British scientist
surE thING
One thing is guaranteed, and we all have to
face it—one day we are going to die. Actually,
according to American statesman and scientist
Benjamin Franklin (1706–1790), there are only
two guarantees—death and taxes.
BACK tO sChOOL
Well, yes they could. About 400 years ago, astronomers proved beyond a
mathematical doubt that Earth goes around the Sun. They were persecuted because
they opposed the Christian Church’s teachings and upset “accepted” knowledge.
But they paved the way for a series of revolutionary discoveries in many fields—
astronomy, physics, and medicine—that laid the foundations of modern science.
At one time doctors believed that the human body was made up of four humors
(black bile, yellow bile, phlegm, and blood). That was another idea the scientific
revolution helped lay to rest. Phew—some of those old cures were scary! For example,
when people turned red in the sun, it was believed that they had too much blood.
Bloodletting (when you purposely cut yourself) was practiced to balance their humors.
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