How science “reasons” to come to conclusions about natural phenomenon
“If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts, he shall end in certainties.”
Francis Bacon, The Advancement Of Learning
How science proceeds or works has been subject to many ideas. Often, people talk about ‘the scientific method’ as if there is some methodology applied to all science that is settled, understood by all scientists and which leads us to certainty. ‘The’ scientific method does not exist. There are methods used in science and how a theoretical physicist works as compared to a geologist, organic chemist, ecologist or physiologist can be as different as the ways in which a geographer works and an historian. In some ways the problem lies with scientists. We are not good at explaining how we work or explaining the differences between the disciplines in which we work. Just the term ‘science’ on one level is meaningless (which science? What type of science?) yet we continue (especially in schools) to use a generic term to cover quite different subject areas. I’ll admit that the term ‘humanities’ can do the same job and may well cover quite separate disciplines, e.g. geography, history, religious education etc. But we don’t often lump them together expecting one person to be able to understand all the disparate disciplines. Yet in science, particularly in teaching in schools, we do.
Science utilises a range of ways of working and reasoning, like most academic disciplines. Science can be practical and experimentation lies at the heart of many scientific disciplines, but not all. Science can also be observational, but again not always. A common attack on evolution is the lack of ‘observation’ – “nobody ‘saw’ one animal change into another, nobody has seen major evolutionary changes; nobody was there when life first began.”
As an argument against evolution, it initially looks compelling to many people. Yet there are simple counter arguments – for example nobody has ever ‘seen’ an atom close up to look at its structure and certainly sub-atomic particles have never been ‘observed in any conventional sense. Does that mean that the theory of atoms is suspect? That sub-atomic particles clearly do not exist? Of course not, but these counter arguments do not seem to be persuasive to the creationist.
Having an understanding of the nature of science or ‘how science works’ is at the heart of my definition of scientific literacy. Understanding that all science is ‘provisional’ – that is, we do not say that science is about the search for truth and that all science, even the most established scientific facts, are open to change – is actually a strength of science and not a weakness.
So how do we reason about things in science?
Deductive or Inductive?
Science can generally operate in two ways:
Deductive Reasoning (top down)
Starting with things that we know to be true (premises) and from these confirming our ideas through a process of logic. The classic example being:
- All men are mortal
- Darwin is a man
- Therefore, Darwin is mortal.
Inductive Reasoning (bottom-up reasoning)
In this case we start with evidence which we believe will support a particular conclusion, inductive reasoning however does not require the outcome to be true, merely probably true.
In science the inductive reasoning route is the route applied to almost all scientific enquiry. As such scientists avoid making definitive statements about the ‘truth’ of any idea, concept or theory. Scientific theories (even gravity) then are probably true but never certain to be true. In real life some theories will have a higher level of certainty than others (gravity again) but at no point can we or should we say that even gravity is proven, true, certain etc. There may (even if we think it inconceivable) be some part of the universe where gravity acts in a way that counters our current understanding.
Deductive science is really ‘theory confirming’ science. In school science we do spend a lot of time on theory confirming. This is to be expected. The science we teach is, for the most part, the science that is generally accepted and for which the scientific community has reached a scientific consensus. Kuhn called it ‘normal science’. The basic scientific concepts that we are teaching and what we have taught for over 100 years is the science that has largely not changed. Newtonian Physics for example is still a key aspect of our physics education.
In biology photosynthesis in its basic form is exemplified by a model equation:
This equation is not what ‘actually’ happens but is a model that summarises many complex processes. To an extent the equation is not ‘real’ yet it is accepted by all as a way of describing the process of photosynthesis. This equation was first worked out by Julius Sachs around 1862-4. It has remained unaltered since then.
We also teach newer ‘established’ science – e.g. plate tectonics which was first described in a theoretical way in the 1960s. But what we do not do in science education is teach untried, untested controversial science that has not been through the science ‘filter’. So calls for the inclusion of Intelligent Design to be taught as ‘another side to the argument’ are nonsensical. Intelligent Design is not science and has yet to prove itself as science. We don’t teach it because it is not science.
How does science become ‘accepted’?
Lynn Margulis (1938 – 2011) had an idea in 1966 – she postulated that some organelles we find in cells – mitochondria (responsible for energy release during cellular respiration) and plastids e.g. chloroplasts, essential for photosynthesis, originated as free-living bacteria which were assimilated into cells and have, over time evolved to become part of the organism as a whole. Her theory of endosymbiosis was not immediately accepted, her paper being rejected by several journals. She knew that what held sway in science was not the idea or the person, but the evidence and so she set about gathering the evidence to support her idea. We did not teach endosymbiosis in schools io the late 1960s, the 1970s or, for that matter, the 1980s. It took decades for her theory to be accepted. In 1995 Richard Dawkins had this to say:
I greatly admire Lynn Margulis’s sheer courage and stamina in sticking by the endosymbiosis theory, and carrying it through from being an unorthodoxy to an orthodoxy. I’m referring to the theory that the eukaryotic cell is a symbiotic union of primitive prokaryotic cells. This is one of the great achievements of twentieth-century evolutionary biology, and I greatly admire her for it.
The work required for new ideas to be accepted in science should never be underestimated. Margulis showed that evidence is the currency of science not ideas or ideals. Hers is not the only story of ideas which take time to be accepted and many others, including the work of Niles Eldredge and Stephen Jay Gould in the field of evolution itself are not simply accepted as they ‘sound right’ or ‘seem to make sense’.
Intelligent Design could just be another case of wishful thinking – things ‘look’ designed, so, therefore, they must ‘be designed’. Many, including Dawkins have written on this subject. But why we should not teach intelligent design need not be a case of science rejecting intelligent design through bias or conspiracy. We don’t teach it because as it stands it has little to no support from mainstream science and no evidence in its favour that is compelling. Even with compelling evidence Margulis’s ideas took a long time to be accepted. That’s how science works.