I've just finished reading through the last few pages that had been posted yesterday while I was out. I have to say I'm still perplexed about this null hypothesis issue. How can it still be so difficult to comprehend, even after all the exhaustive explanations we've given?
Please allow me the courtesy of taking one more whack at explaining it. OK?
The concept of a null hypothesis is not complicated, but it requires a grasp of the concept of
falsification. Falsification means the
disproving or
nullification of an idea or concept. It is a very important concept to science.
First of all, the main points:
- A null hypothesis is not a normal kind of hypothesis. That is, it is not created with the intent of proving it, nor is it assumed to be a proven fact.
- The null hypothesis is basically the default assumption that the researcher's hypothesis is not true.
- It is merely assumed as a default position (due to lack of evidence), until such evidence is confirmed to falsify (disprove) it.
- The researcher does not have to believe the null hypothesis is true; in fact the entire point of the research is to falsify it.
- The null hypothesis is to be stated in the simplest and broadest possible terms, in order to make it easy to falsify in an unambiguous way.
- The only reason it is there is to eliminate confirmation bias from the research.
- The null hypothesis is applicable to any field of research that studies the objective, material Universe.
Note that at no point is the null hypothesis intended or assumed to be
proven, it is merely assumed true on the basis that
no evidence exists to refute it. Critical thinking posits that without evidence, a claim is not to be assumed true. Of course that does not mean it is
assumed to be false either, but there is simply no good reason to believe it.
Here's a hypothetical example:
Let's assume for the purpose of this example that an ornithologist has received unconfirmed reports that white crows have been sighted in his local area. He personally has never seen an albino crow, but he suspects that such a thing might exist, so he decides to investigate the matter.
So the hypothesis he seeks to prove in his research is:
"Some crows are white."
Now the prevailing science dictates that all crows have black feathers. In the absence of evidence, there's simply no basis to assume otherwise, right?
Of course it would be wrong for him to just
assume the white crows exist on hearsay without any material evidence, so he must posit a
"null" hypothesis as a baseline goal for himself to falsify.
The null hypothesis essentially negates his own hypothesis. It states:
"All crows are black."
The null hypothesis is
unproven. In fact, it's unprovable (there's no possible way for the ornithologist to have examined every single crow in the world).
But the null hypothesis is not an
argument from ignorance, either. The null hypothesis is not a
claim per se, and therefore does not need to be proven; it exists only for the purpose of being falsified, to prove a point. The researcher doesn't even believe it to be true (he's trying to prove it
wrong, remember). But he must assume it's true, because the burden of proof is on
him as the claimant to prove evidence to the contrary. To prove his hypothesis, he must
falsify the null hypothesis.
This process may seem backward and counter-intuitive, but it is a very important step to ensure the researcher's own bias does not influence the outcome of the research. The researcher might feel 100% certain that his hypothesis is correct, but he must nevertheless assume it is wrong (for the purpose of research) until he can produce evidence to support it. If he cannot produce evidence, then he must concede that his hypothesis has not been proven and is probably wrong.
For the ornithologist to falsify the null hypothesis, all he has to do is capture
a single white crow. Just one, and the null hypothesis will be falsified. He could then perform DNA testing on the animal to determine its origin, and publish his results in an ornithological journal. With every independent DNA test that confirms his findings, his hypothesis becomes stronger until the whole world must accept the fact that white crows exist in the world. This is how science is done, and now human knowledge is advanced.
See how that works? Do you have any questions?