Tuesday, 22 July 2008

A wise old saying

There is an old saying in the law: as the allegation is more serious so should the proof be more clear. I am not going to turn this musing into a paper on burdens and standards of proof, but I do want to look at that saying and see what it means in practice.

There are two different principles at work here. One is that the more unusual the activity complained of the less likely people are to believe that it occurred. For example a witness who says "I was standing at the bus stop outside my house at 8am waiting for the bus to take me to work" is describing something very ordinary and everyday, it takes no leap of faith to accept that he is telling the truth. Were he to say "I was standing on my head on top of the bus shelter waiting for a big pink fairy to carry me to work" even the kindest soul is likely to have some difficulty accepting it as true. It is probably right to say that the commission of a very serious criminal offence is something which does not happen as often as the commission of minor offences. To take an obvious example, there are fewer murders in London each year than there are examples of littering the pavement. An accusation of murder necessarily requires the prosecution to persuade the jury that something very unusual happened and that, of itself, makes the jury less likely to convict the Defendant without clear evidence.

The other principle is that where the penalty for a particular offence is a serious penalty it is fair to expect the offence to be proved very clearly. Not only is murder a rare occurrence, it also carries a mandatory life sentence. It is hardly surprising that juries often take a long time to deliberate in murder cases even where the evidence is very strong indeed, they know the consequences of a guilty verdict and will not cut any corners.

These thought-processes merely reflect standards that have developed over time in our society. We have a well-developed sense of fairness, we know what is serious and what is trivial, we know that it is fair to give serious matters more mature consideration than trivial matters. Perhaps it is better expressed as a negative: we know it would be unfair to convict someone of murder unless the evidence is very clear indeed. Many murders are just ordinary assaults with highly unfortunate results but that does not prevent the jury from requiring overwhelming proof of the assault where the victim died and less powerful proof where exactly the same type of blow merely left the victim bruised.

This reasoning is now coming to the fore in the great global warming debate. When the hoo-hah started some years ago only a small number of people felt a need to examine the theory in any detail because the only threatened consequence was that the planet would get a bit warmer. How nice, we all thought, a longer cricket season, less ice on the roads in winter, lower heating bills, let's have a bit more of it if it's not too much trouble, thank you.

Then the predictions turned to plague, famine and pestilence. That's a rather different scenario. We don't like plague, famine and pestilence, we must stamp out this evil. There was still relatively little interest in the science behind the arguments because there was no price to pay except to cut down a bit on coal and petrol. That's not a problem, I will drive at 60mph rather than 70 in order to prevent starvation in Africa. All that was required was equivalent to not dropping litter, it was no great inconvenience and a lot of good would result.

Over the last three or four years things have changed dramatically. All of a sudden we were told we must stop driving, stop flying, stop this, stop that and we looked at how those changes would affect our lives. Those who hanker for life in a cave with nothing but a small cabbage patch for food and hand chewed raffia clothing could not be happier, their dream is coming to pass. The rest of us face calls for such dramatic changes to our comforts that we ask whether it really is necessary. Suddenly we are threatened with the equivalent of the mandatory life sentence and, not surprisingly, we ask whether the case for such a serious penalty is proved with sufficient clarity. The accepted, perhaps even orthodox, position of the alarmists was accepted without debate when it did not threaten us, then we became a jury.

The task of a scientist when he appears before a jury is to explain the science in handy bite-sized chunks so that it can be understood by those who need to understand it in order to reach a decision. If he is exposed as an obsessive the jury might well be reluctant to accept what he says without supporting evidence. In the global warming debate we find obsessive scientists on both sides, we are bombarded with hyperbole and worst case scenarios. What we want to know, sitting in our jury box, is whether the case of the alarmists is proved. Do they have sufficient evidence to justify the life sentence with which we are now threatened?

I wonder whether, when making their doomsday predictions, they realised they were making their task of persuading us about the science harder rather than easier.


Neil said...

Dear David,

Nice post. At last someone (other than me of course) is asking the No. 1 key question in this debate - which side bears the burden of proof?

If I can suggest three further key questions:

(1) Are we actually in the jury box as you say, or are we in the dock?

(2) Is the use of the precautionary principle in the arguments of one side, with the implied attempt to shift the burden of proof, valid or not?

(3) How well has each side in the debate allowed the other side the opportunity to present its case?


TheFatBigot said...

Greetings Mr Neil

How nice of you to call me David. It's such a nice name. Not my name, but a nice name nonetheless.

I agree that the points you make are important. Much of the presentation of the AGW theory on television and in the press is affected by editorial decisions that the theory is correct, there has certainly been a BBC edict to that effect. No doubt such decisions are a direct result of the doommongers getting in first and it is hardly surprising that many people accept a proposition when everything they see and read tells them it is correct.

Interestingly, a recent opinion poll found that a majority of those questioned did not accept the doommongers case in its entirety despite only one side of the debate receiving regular coverage.

The first and third of your points are essentially presentational. Because the alarmists have the ear of the broadcasters they determine how the debate is conducted. This will probably remain the case until editorial positions are changed. It might happen, it might not, time will tell; but the more extreme the presentation by the alarmists the less likely any reputable broadcaster is to continue supporting them. In this respect Dr Hansen's call for oil executives to be charged with crimes against humanity might prove significant. His approach cannot withstand rational scrutiny and, frankly, makes him sound obsessional and perhaps even unhinged. The more such outbursts we hear, the more likely the mainstream broadcasters are to look on him and his merry men in a less favourable way.

The precautionary principle raises a slightly different issue (albeit that there is some overlap). The more painful the remedy, the less likely people are to be prepared to accept it even if they are convinced by the scientific evidence.

By analogy, we might be prepared to pay money to a homelessness charity, but ask us to take a homeless person into our homes to live and we say "I'm not prepared to do that". No matter that it would solve the problem of homelessness at a stroke, it is not a price worth paying to solve the problem.

There has been a good example of this recently in the reaction to the government's announcement of a plan to spend £100billion on windfarms. Our taxes go up and up, prices are rising, wages are kept down, the government tells us money is tight and then says it wants to spend £100billion, a sum equivalent to one sixth of its total annual tax revenues. People asked whether it is worthwhile and this had a knock-on effect by raising questions about not only the effectiveness of the cure but also the strength of evidence in support of the alleged problem.

I do not pretend to understand the science except in the very broadest terms. But I do know that the AGW theory strikes me as fanciful and the cost of doing what the alarmists say we must do to "solve" the problem is a price people will not be prepared to pay. The precautionary principle is all very well but it necessarily involves a balance between the weight we give the problem and the weight we give the cost of the solution.

In my view the precautionary principle does not shift the burden of proof because, by definition, it requires the problem to be defined with precision; and the more precisely it is defined the better we can see the pain the solution would cause.


ziz said...

If you go to DeFRA
and look at the pafe on the formationof the Climate Change Committee.

Formed and running in advance of the legisaltion to set it up. You will find a link to a very interesting document.PDF

Committee on Climate Change
Workplan May 2008

This 28 page document in theory outlines what you raise- a need to examine the evidence and make recommendations . The Committee is of course stacked.

Sir Brian Hoskins and Lord Robert May, Professor Jim Skea and economists Dr Sam Fankhauser and Professor Michael Grubb will make up the new Committee, headed by the newly-appointed Chair designate Lord Adair Turner.

This week they addedd professor King a lady from Birmiongham who has been bangin g on abourt global warming for a long time.

YOu need to read it but a Para on Page 4 is worth listing here ..

"Understand the key uncertainties in climate science, and in particular the complexity of potential feedback loops, amplifying and dampening mechanisms, and uncertainties about their power."

This is under the sub heading

Scientific estimates of likely future temperature effects. The key measures we will focus on are probability estimates of how likely different levels of GHG concentration (e.g. 450, 500, 550) are to produce global average temperature increases of more than 2° centigrade, 3° centigrade, 4° centigrade etc. To understand the range and the uncertainty of these distributions we will:

Now if you want to understand the key uncertainties in climate science you will need a very long time because there is no single unifying concept.

It is rather like the old saw, 4 ecomomist will give you 7 opinions why ...

I have spent a lot of time trying to unravel the science base and find it gets rather like mediaeval bishops arguing how many seraphims will fit neatly on a pin head.

e.g The tropical troposphere has not heated up as expected by all models.

Data must be wrong.

Ah! the records arw rong because the temperature sensor on the satellite is fooled by darkness .... No. No. the temperature sensors are OK. ... well we haven't taken account of the recession correctly. (All satellites fall prey to Mr Newton's gravity and fall down to earth so their path varies over time) etec,., etc.,

This post gives a small flavour
"Friday, August 12, 2005
Hot Air ALERT..Climate Mongerers at Work "

"Research led by the Met Office's Hadley Centre makes the entirely unsurprising conclusion, that; choices made by each research group in constructing climate datasets can have a significant impact. Initially satellite and balloon-based systems used were designed to provide the best possible snapshot of the global weather at any time, rather than to long term monitoring. The new research shows clearly that the choices made in homogenising the data have a particularly strong effect on estimates of climate change – or in simpler terms, if you use different methods…you obtain different results."

Search the site at the link "satellite+temperature"

I declare my interest to being a sceptical scientist. The climate is changing , it has done frequently, anthropogenic effects are negligible and local.

TheFatBigot said...

Thank you Mr Ziz. I wasn't aware good sense had started to prevail and that this question was being addressed. It makes one wonder why it was thought sensible to commit £100 billion for windfarms a few weeks ago when the new committee must already have been planned.

As to your observations about the uncertainty of the science, one reason I opine on this subject is that I have looked into much of it myself. I am no scientist but I know nonsense when I hear it and I know that a chain is only as strong as its weakest link.

We see massive areas of (apparently) genuine scientific dispute whether we look at:
- temperature measurements (urban heat effect, accuracy of satellite readings, accuracy of adjustments of old data, range of data points and more)
- CO2 measurements (reliability of ice core data, relevance and accuracy of historic physical measurements, effect of oceans out-gassing and absorbing, effect of population growth regardless of industrialisation and more)
- the sun (correlation v causation of sunspot activity, effect of increased solar activity on clouds, effect of water vapour compared to CO2, effect of solar activity on oceans and more)
- the oceans (ability to absorb man made CO2, cause and effect of oscillations, cause and effect of acidity, cause and effect of marine plantlife and more)
- longevity of CO2 in the atmosphere (is it 5 years, 12 years, 20, 100, 200, 500; what causes it to disappear over time, is longevity always the same and more)
- effect of CO2 in the atmosphere (logarithmic v linear, comparison to water vapour, why no frying when levels high in the past, why no increase in temperatures 1940ish-1960ish, why no increase in temperature since 1998 and more)
- what effect will reduction in human CO2 emissions have?

Then there are the disputes about the IPCC models with their built-in positive feedbacks for CO2, absence of positive feedbacks for other factors and weightings in favour of data which support the IPCC's desired conclusion.

All of that comes before the most important question: is the cost of reducing emissions in proportion to the resulting benefit? The reason the science comes first is, of course, that it is necessary to prove a benefit from reducing emissions before we need give one second of thought to doing so.

Let's hope the new committee will approach the issues objectively. Support for the IPCC position does not necessarily mean the committee has failed, but it will have failed if it examines the evidence with a presumption that the IPCC is correct. It must start with a blank canvass.