For too many Americans, a ‘theory’ is a casual thing like ‘I have a theory as to where I lost the keys.’ They then translate this casual understanding, mentally, when they hear “Theory” referencing science without truly understanding the import of the word. This guest post from chemist chparadise provides perspective on this.
There’s been enough of a brouhaha around [the web] and on “climate skeptics” sites lately that it inspired me to write briefly my own take on how scientists view such things as hypothesis, theory, fact, and the like. Other scientists may have their own way of phrasing things, but I like to think that I’m sticking fairly close to the line for the scientific method.
Background for me, for those who don’t know: graduate student in organic chemistry. I’m not a climate expert, but I read the articles in Science and Nature every week and I have a very firm understanding of the basic science underlying global warming – the chemistry is infallible.
Anyways, some useful terms / takes:
When a scientist notes something is a “fact”, it’s usually referring to direct data measurement. Thus, a monitoring station may have registered a 1 degree temperature difference from year to year. That’s a fact, and that’s the underlying data that drives the rest of the scientific process.
When a scientist talks about a “hypothesis”, that’s a working thought that drives investigation. It may or may not be accurate, but by asking the question – with good logic behind it – the scientist can go find out whether or not it’s true. So, for instance, in the climate debate the hypothesis might be that because carbon dioxide absorbs infrared radiation at a wavelength that the earth re-emits, the earth should be warming. And, because carbon dioxide dissolves in water to produce carbonic acid, the earth’s oceans should be acidifying. These are merely hypothetical in the absence of supporting data.
When a scientific hypothesis advances to a theory is when the hypothesis and data match up. When the hypothesis and data don’t match up, a new hypothesis is created which is then checked against the data. And then a new theory may emerge. I’m putting the latter in italics because it’s such an important part of the scientific method. There are countless times where perfectly good hypotheses were proven wrong. I’m working on a project right now where, literally every time we think we understand the system, we get some sort of data that makes us change our hypothesis. We may never get to the point of theory on this project – that’s how frustrating it is.
ETA on theory: A theory is predictive, too – and when the predictions are proven false, the theory has to be reworked. I alluded to this in my rant about how every time we think we know what’s going on we’re proven wrong, but I should have been more explicit 🙂
What’s really important to note, in the end, is that several disputed scientific theories are just that – they are scientific theories. The general public thinks that “theory” means that there’s a lot of doubt on the part of the scientist. Rather, in science, a theory happens when there’s little doubt. Scientists have this annoying way of still leaving a small chance that they may be wrong…in fact, they’d be shitty scientists if they didn’t leave that chance…but, that iota of doubt (we’re talking 0.001% chance material here) is seized upon and misunderstood to leave the impression that scientists don’t have nearly the evidence that we actually do.
The take home message here is at least three-fold.
- A scientific theory has a huge amount of evidence behind it. The theory of evolution and the global warming theory have huge amounts of supporting evidence, For scientists to give them up would require extraordinary disputing data – data that a few emails talking about massaging data to give the best possible conclusion simply cannot provide.
- The word “theory” is horribly misunderstood by non-scientists. Laymen and women seem to get the impression that there’s a lot of doubt, since we say “theory” and not fact. That’s a rather unfortunate happenstance, since it leaves us scientists open to criticism and doubt that we don’t deserve.
- Scientists really need to get better at PR. I can sit here and write this diatribe, but I know I’m preaching to the choir. I’ve given similar diatribes on more mixed sites to more mixed reactions, but I keep trying. I’ve converted one person to my understanding, and I’m proud of that, but I wish I could do more. My “advocacy” efforts have converted one warming skeptic, one college freshman from engineering to chemistry, and one high school student from literature to biology. It’s a limited record, but I won’t give up trying.
I hope this has helped at least a few people understand what scientists mean by fact, hypothesis, theory, etc. I wish that we had greater literacy in science as a citizenry, but in this case, all politics are local, and all I can really do is convert people one-by-one.
Talking about “law”: A quick take on what a scientist considers a “law”. A law is something that has overwhelming evidence for it, and very few theories advance into law. The laws of thermodynamics and the law of gravity are such. Laws have no contradictory data against them, and I’ll admit that something like evolution and global warming will never get to “law” – they’ll remain “strong theory”, since it’s almost impossible to design experiments to get the 99.9999999999999999% burden of proof a “law” requires, vs say the 99.999% burden of proof that a theory requires.