An Introduction to Critical Thinking and Creativity - always yours

THE DEAR METHOD 115
13.1.1 Step 1 : Define the theory to be tested
The first step of hypothesis testing is to define clearly the hypothesis that is to be
evaluated and make sure we know what it means. If the meaning of a hypothesis
is unclear, it will be difficult if not impossible to test it. Here are a few things to
bear in mind:
• Clarify keywords: Some people think that everyone is surrounded by an
aura field, a field of energy. To test this hypothesis, we need an explanation
of what an aura energy field is. Is it the same as the electromagnetic energy
that is studied in physics? If so then there are ways to test its presence. In
fact this is probably true since our bodies have warmth and so they emit
heat, which is a form of electromagnetic energy. But then the aura field is
not something very remarkable. On the other hand, if this is not what is
meant by an aura field, then further clarification is needed. Otherwise there
is no way to test the hypothesis and we have no reason to believe it. We
might as well say there is an invisible and undetectable unicorn dancing on
everyone's head.
• Be precise: A more precise hypothesis is less likely to be misunderstood.
Take the claim that gold is a good investment. Its meaning is not obscure,
but more precision will provide better guidance. Are we supposed to buy
real physical gold, or stocks that are linked to gold? Is this good investment
for the short or long term? What kind of return are we talking about? Taking
these concerns into account might give us a more concrete claim, such as
investment in physical gold or gold stocks will beat inflation and perform
better than major stock markets in the next five years.
• Clarify the scope of the hypothesis: The scope of a claim is the range of
things the claim is supposed to be true of. Take the claim "swans are white."
Is this true of all swans, most of them, or just some of them? The scope
of the claim makes a big difference as to the evidence we need to check
whether the claim is true. "All swans are white" is false because there are
black swans in Australia. But if the claim is changed to "some swans are
white," the existence of black swans becomes irrelevant and what matters
is whether you can find at least a few white swans. But consider also "most
swans are white." Knowing that there are white swans and black ones will
not help us decide whether it is true. We need a detailed statistical survey to
find out. As you can see, the scope of a theory makes a big difference to the
evidence needed to test it.
13.1.2 Step 2: Gather the evidence for and against the theory
To evaluate a hypothesis, we gather all relevant evidence.
• There are two types of evidence: Supporting evidence are facts that increase
our confidence in a hypothesis. Counterevidence are facts that de-