Tuesday, September 23, 2014

What do scientists believe?

I think there are many misunderstandings about what science is, how it works, and what scientists believe about the world.

Science is a process -- a tool -- for discovering things about the universe. Because of this, scientists hold a plurality of beliefs -- saying "what do scientists think?" is a bit like saying "what do Australians think?" -- there are as many answers as there are scientists.

With that caveat in mind, let's examine what science does.

Science is a process by which we can show ideas to be wrong. The phrase "scientifically proven" is incorrect -- science never proves anything*. Science can only disprove theories, and any currently-accepted scientific theory is pending invalidation.

A good example of this is Newton. His law of universal gravitation is a fantastic tool for understanding the motion of heavenly bodies. Is it "right"? No. For centuries people believed that Newton's laws were True (with a capital T), in the sense that they described the workings of the universe. In the 20th century, Einstein's theory of relativity revised Newton's laws, making them more accurate when dealing with very-high-speed objects. Is Einstein's theory "right"? Probably not.

However, despite their imperfections, both theories are extremely useful at describing motion. So in a sense, they are actually both correct theories. It's a bit like someone asks you how old you are and you say 28 and they say "happy birthday!", so you reply, "well 28 and 112 days 6 hours 25 minutes ..." -- Sometimes all that extra precision isn't needed. Both theories are right, but we (currently) think that the theory of relativity is more right than Newton's laws. In the future, there may be further improvement's to the current theory which may make it more correct still and better approximate the universe's behaviour. Of course, no human endeavour will ever be perfect, and I strongly doubt humans will ever articulate a set of theories that describe exactly how the universe works.

Note that this is a different perspective from what previous generations of scientists may have said. This is because the 20th century saw some blunt boundaries placed on what humans can know.

The first was Godel's incompleteness theorem, which basically says that there are things in maths that can never be known -- that is:

  1. truths that we can never show to be true
  2. falsehoods that we can never show to be false
  3. our mathematical system can't demonstrate that it is internally consistent
This was pretty controversial at the time, and I think there are probably many scientists today who don't really think about this much.

A second was Karl Popper, whose theory of science described what I consider to be the scientific method. That is,

  1. create a new falsifiable theory
  2. try to disprove it -- if you succeed go to 1
  3. if you fail to disprove it, then consider that the theory has some merit.
  4. keep trying to disprove it by creating new theories
Falsifiability means that it is possible to show a given theory to be false. It is a common criticism of theories such as "intelligent design" which are sufficiently vague that they cannot be disproven. In analogy, Bertrand Russell coined the idea of a celestial teapot, orbiting the sun somewhere between Earth and Mars. This is not a falsifiable theory, but just because it is not falsifiable does not make it true.

So, what do scientists believe? All kinds of things, many of which are wrong. They're only human, of course. Science is a messy business -- it is by no means a straight line journey towards truth. There are vested interests and power games: interpretation can be bent to serve entrenched interests and results can be corrupted by money. Science is a human endeavour, and suffers from all of our human foibles. Max Planck reportedly said that "science proceeds one funeral at a time," which I interpret to mean that old scientists are set in their ways and have their own cherished beliefs (and personal position of prestige) which they are less willing to critically examine.

In summary, there is a saying: all models are wrong, but some are useful which I think is a good way to think about science.

This post was written by Angus Wallace and first appeared at guesstimatedapproximations.blogspot.com.au

* I wrote "science never proves anything" -- this is true, but it may mislead. Scientists use the words theory and proof differently to other people. In science, a hypothesis is an idea about how something might work. If we try to disprove a hypothesis and fail, then we would call it a theory. Non-scientists often hear the word "theory" and think it sounds weak or inconclusive. In fact, we still refer to Newton's theory of universal gravitation and Einstein's theory of relativity -- these are both extremely well-established models of reality.

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