Definition of Terms
There are a number of words and phrases that are used in sometimes imprecise ways by the writers of popular science. For the avoidance of ambiguity, I use the following definitions throughout this piece.
An observation is something that can be sensed and measured.
There is no requirement in this definition that the sensing be done by a human being. One non-human example is the infra-red sensor. Nor is there any requirement for the
measurement to be quantitative, it can be purely qualitative.
A conjecture is an explanation that is purported to explain a set of observations. The word “theory” is often used mistakenly in this context. The “steady state theory” of
the universe is in fact a conjecture.
An experiment is limited in this piece to mean a set of actions and measurements designed to either support or refute a conjecture.
Evidence is a set of measurements from an experiment and associated logical arguments used to support or refute a conjecture.
A theory is a conjecture for which the evidence that supports the conjecture greatly outweighs the evidence that refutes the conjecture.
A conjecture and a theory are both falsifiable if it is possible gather evidence which leads to refutation.
The changes in ideas about planetary motion can be used to illustrate the above perhaps somewhat dry defintions. In ancient Egypt, the theory was of Ptolemaic epicycles. Given the capabilities of measuring equipment at the time, this was as good as it could possibly be. This was falsified by Sir Isaac Newton when he produced Newtonian mechanics. His theory was very successful at explaining the motion of the planets. However, the motion of Mercury around our sun was not entirely in agreement with Newtonian mechanics, so it was known that there was an unresolved issue. It was not until Albert Einstein produced his theory of general relativity that the motion of Mercury could be properly explained. In that sense, Newtonian mechanics has been falsified as a theory of how the universe works, even though it is completely adequate for the purposes of everyday living.
Other examples of observations, experiments that and theories that have changed ideas about the universe include the discrete nature of matter (Millikan), the existence of the atomic nucleus (Rutherford), quantum states (Niels Bohr, Paul Dirac and John von Neumann) and the Standard Model (particle accelerators).
Examples of conjectures that have been refuted include Descartes assertion that colours were discrete (refuted by Sir Isaac Newton showing that white light could be split into its component colours), phlogiston (refuted by a number of chemists at the time showing that it had to have negative mass) and the steady state “theory” of the universe proposed by Fred Hoyle (refuted by Hubble’s observation of red shift).
Theists and God
The conjecture of God (or gods) has been around for millenia. To people of the pre-scientific era, and in the absence of any better measurements, this was the best that could be achieved: a god is a convenient mechanism for explaining things which are otherwise inexplicable. Scientific theories have given us much more powerful ideas about about how the universe and our world work, often in very precise mathematical terms.
I have in recent months asked any theist who would care to engage in the question to provide falsifiable evidence for their claim of the existence of God. The great majority have responded in one of two ways, either to ignore the question or to offer only observations without suggesting any experiments or ways of gathering falsifiable evidence. The remaining theists have resorted to giving me personal abuse.
A few of the theists who ignore the question of falsfiable evidence give other responses. Some present me with a false dichotomy, that God either does or does not exist, and that a failure to prove God’s non-existence thereby proves God’s existence. Others make the assumption that the nature of both time and causality as we currently understand also applied at the time of the Big Bang (“Something must have caused the Big Bang, and that something must be God.”).
I make the following request to all theists who wish to engage with me on the question of the existence of God: “Please get an understanding the nature of scientific thinking before making fools of yourselves. Thank you.”.