In reading David Deutsch’s brilliant book, The Beginning of Infinity, I finally came across a couple of simple reasons why untestable theories in science are a dead-end and why the explanatory content of a theory matters. It’s very common for me to harp on about empiricism and evidence to friends and folk I debate on subjects like God, heaven, homeopathy, alternative medicine and other realms where science cannot speculate, or has to no avail. I’ve never, however, managed to condense such lectures into conversational fragments that didn’t make them hate me by the time I finished. For that reason alone, I’m glad I came across Deutsch’s book; for my argumentative arsenal has increased.
Let me start by asking a few questions:
Q1 – What is the single factor that science, pseudoscience, and non-science have in common? (This is not a trick question).
A1 – The answer is that they started thousands of years ago, with the same base of information, which is relevant to the conclusion at the end of this post.
Q2 – Now, what differentiates science/pseudoscience, and non-science?
A2 – Testability*
Put it that way, A2 is obvious. As Karl Popper wrote: empiricism is the demarcation point between science and non-science (the criterion of demarcation). In other words, the testability of a hypothesis will tell you if it can be improved by experience. And, if it can’t, there is nothing to rely upon except authority and the rejection of authority is what allowed the scientific method to come into being. This brings us to Deutsch’s first science nugget:
Deutsch’s 1st Science Nugget: an untestable theory cannot be improved upon by experience