In my book The
Science & Economics of Climate Change: How the Mechanisms and Physics of
the World Really Work, I have a bulky section on what many think of as “the
science of climate change”. When you hear environmentalists – from the serious
scientists, to the raving climate alarmists – you’ll often hear them say
"The science is clear on this" or "We have to listen to what the
science is telling us and act urgently". And when they say those words,
they are signalling to you that they haven’t got a thorough grip on the matter,
because no one who understood the complex, multivariate analyses required for a
subject like climate change would ever use the term THE science.
How to do science
Regarding the methods associated with science,
let me start with a poser. You've been tasked with hiring a team for a science
project as yet unknown to you. You have 2 teams of eight from which to choose
(call them Team A and Team B), and you know only one thing about the teams.
Here's what you know.
Both teams worked independently on the same project; it was an investigation into seventy deaths that occurred in a factory on one day last September. Everyone in the building was found dead on the floor one day, and both teams knew that the factory had recently started to use a new chemical X, but they weren't sure for how long. Team A and Team B were given 35 of the dead bodies each and access to the entire factory, and were tasked with finding the cause of 70 deaths. Here's what they did differently:
Team A gathered evidence A, B, C, D, E and F and sat down together in a room discussing all the possibilities. After some deliberation, they hypothesised that methyl isocyanate had escaped into the factory's atmosphere and caused the deaths. After this, they did a postmortem on the 35 bodies to see if the cause of death matched their hypothesis. The 35 bodies they tested all had methyl isocyanate poisoning.
Team B did the post mortems first, found the cause of death as methyl isocyanate poisoning, and then gathered evidence A,B,C,D,E and F to see if the evidence matched their post mortem conclusion. It did. The evidence suggested that methyl isocyanate had escaped into the factory's atmosphere and caused the deaths.
That's all you know about the teams; you have a project coming up, and you need to hire Team A or Team B. Which do you choose to hire?
Conclusion..............
To see which team is a better candidate for your hiring, we need to consider how science works at a general level - and for that, we should start with two kinds of inference; modus ponens and modus tollens. For those unfamiliar with the terms, modus ponens means 'method of affirming', and modus tollens means 'method of denying'. They are rules of inference, where if the premises are true, we can reach a logical conclusion and make inferences about how the world is. We say an argument is a valid argument when it is not possible for the conclusion to be false if the premises are true.
With modus ponens, if we know that P is true, and we know that P implies Q, we can infer that Q is true. So for example:
If today is Tuesday, then tomorrow will be Wednesday
Today is Tuesday
Therefore tomorrow will be Wednesday
With modus tollens, if we know P implies Q, and we know that Q is false, we can infer that P is not true. So for example:
If today is Tuesday, then tomorrow will be Wednesday
Tomorrow will not be Wednesday
Therefore today is not Tuesday
In the first case, we are affirming the antecedent, and in the second case, we are denying the antecedent. That is to say, with modus ponens we are affirming that today is Tuesday, meaning tomorrow is Wednesday. With modus tollens we are denying that tomorrow will be Wednesday, meaning today is not Tuesday
Now, if all argument forms were as valid as that, and if all premises were as unambiguous as that, then there would be no fallacies committed. But it isn't the case, because some argument forms are faulty, and some premises are ambiguous. Consider this common type of error:
If I have flu, then I'll have a runny nose.
I have a runny nose
Therefore I have flu
This is an unreliable argument, because my runny nose may be caused by something else (like hay fever) that is not flu. Or consider this:
If it is midnight, then my watch will say it's midnight
My watch says it's midnight
Therefore it must be midnight
Here we get into difficulties again, because just because my watch says it's midnight doesn't mean it is midnight. My watch might have stopped at midnight, and it may actually be 1am. We can also see a logical fallacy when we consider an inference in the negative sense:
If the street is wet, then it is raining.
It is not raining
Therefore the street is not wet.
Clearly, this is also unreliable, because even though it is not raining it does not prove that the street will not be wet. It could be that the street is wet due to a burst pipe, or snowfall, or by being washed by the council.
So let's look at the above example with our two science teams. We can see that team A used the modus tollens method whereas team B used the modus ponens approach. Here's a reminder:
TEAM A: Team A gathered evidence A,B,C,D,E and F and sat down together in a room to discuss all the possibilities. After this, they did a post mortem on the 35 bodies to see if the cause of death matched their hypothesis.
TEAM B: Team B did the post mortems first, found the cause of death as methyl isocyanate poisoning, and then gathered evidence A,B,C,D,E and F to see if the evidence matched their post mortem conclusion.
Personally, I would hire Team B, because the modus ponens method is a better method for confirming a hypothesis in science (modus tollens is better for falsification). Team A made themselves candidates for the modus tollens fallacy by gathering evidence A,B,C,D,E and F and hypothesising that methyl isocyanate had escaped into the factory's atmosphere. Here they made an educated hypotheses and turned out to be right, but their method may not have accounted for the other possible conclusions that could be reached from evidence A,B,C,D,E and F.
Team B's modus ponens approach means they began with the 'method of affirming', by doing the post-mortems first and finding the cause of death to be methyl isocyanate poisoning. They then gathered evidence A,B,C,D,E and F to see if it matched their post mortem conclusion, which I think is a better way to make inferences. This approach builds a solid foundation by grounding hypotheses in observable evidence. On the other hand, Team A’s approach, where they formed a hypothesis before examining the bodies, had the potential to run into problems if the post-mortem results contradicted their hypothesis. While this approach can work if the evidence supports the initial hypothesis, it is prone to confirmation bias and could lead to ignoring contradictory evidence. Given the foregoing, Team B's approach demonstrates a more reliable method of scientific inquiry, and they are the Team I’d advise hiring.
There are cases when the modus tollens approach gets you to the right answer more quickly. If the hypothesis is that methyl isocyanate escaped into the factory atmosphere and caused the deaths of the 70 people, they could use modus tollens to frame the logic as follows:
P1: If methyl isocyanate escaped into the factory atmosphere, then all the victims' post-mortems should show evidence of methyl isocyanate poisoning.
P2: The post-mortems do not show evidence of methyl isocyanate poisoning.
Conclusion: Therefore, methyl isocyanate did not escape into the factory atmosphere, and it is not the primary cause of the deaths.
This would open the team up to other lines of enquiry.
In conclusion, modus ponens and modus tollens are essential tools in science, each suited to different stages of investigation. Team B's modus ponens approach is ideal for confirming hypotheses based on solid evidence, reducing the risk of confirmation bias. Meanwhile, Team A's modus tollens approach is useful for quickly eliminating incorrect hypotheses.
For the factory investigation, where reliable confirmation of facts is key, Team B’s method is preferable. In seeing that their approach builds more efficient conclusions on observable data, making them the better choice for future scientific inquiries that require careful validation, we have shared in a good insight about some of the basics of science.
Stay tuned for part 2: Science & Climate Change Part II: There Is No Single Scientific Method
