When I was a final year university undergraduate I took a course that had only one text. Written by Carl Hempel it was a very short book (116 pages) titled “Philosophy of Natural Science” (Prentice-Hall Inc. 1966). What has stayed with me over the years is that it examines how we know what we know.

Using basic principles of logic and reason it explained the nature of a hypothesis, a theory and evidence. Hempel gave a very clear explanation of the “ideal” scientific inquiry as a method of explaining phenomena.

He also demonstrated that we can never fully prove an explanation is true but can easily prove it is not true. This means we can never fully prove that this or that explanation for pain is true but it is relatively simple to disprove one. This is a sobering thought especially when one believes in a particular explanation.

Evidence can thus never be proof. It can only support or fail to support an hypothesis. Examples of hypotheses about pain include: all pain is based on psychological processes, much pain is based on problems residing within muscles or tendons or ligaments or intervertebral discs, and chronic pain is a form of stress response. How do we know which one to believe in without evidence?

When I use the term “evidence based” I am referring to the processes of logic and reason so well explained by Hempel. Reason allows us to go beyond our beliefs. It allows us to see that our observations and experiences are simply one kind of evidence that is not as objective or reliable as testing what we observe.

Evidence remains the best and most open way of supporting one’s opinion. Scientific research may be tainted by politics and money when those who conduct it allow avarice, the desire for power, prejudice and so on to replace reason. This is not a failure of scientific research but a human failure.