Monday, 30 June 2008

Common sense anyone?

An advantage of having no expertise in anything is that one can approach any subject armed with just one's own version of common sense. What is "common sense"? I suggest it is not at all "common" but a very personal thing. It is a combination of our own experiences and the experiences of others who have made a significant impact on our lives and on our beliefs. We store those experiences in our minds and analyse whether a proposition put to us should be accepted by applying the resultant "common sense" - our own, personal, common sense.

Recently there has been debate in Parliament about abortion, should abortion be allowed only where the foetus is 24 weeks old or less (and subject to other conditions, as is the current law) or should be time limit be lower? Opinions ranged from those who are in favour of abortion on demand to those who would not allow abortion at all. Members of Parliament hold such radically differing views because of their personal experiences and beliefs. Those at one extreme say "it is common sense that all abortion is murder, just as if I were to shoot you through the head", the other end of the spectrum says "it is common sense that the world is already overpopulated and anything to reduce population is a good thing". They can never agree yet they are both right because their personal views of common sense support the propositions they put forward. In between those extremes were the vast majority whose minds were open (to a greater or lesser degree) and who would vote according to what they found most influential in the debate. The issue being debated was not one with a scientifically measurable right answer, it was all a matter of opinion.

The position is both the same and different when it comes to an issue which is essentially one of science. The great global warming debate is probably the best example we will ever see of this. At one end stand those who presume mankind to be the most malevolent force the planet has ever known, at the other end stand those who think mankind can do nothing wrong. In between stand those who want to hear and examine both sides of the argument before reaching a conclusion and, of course, the conclusion they reach will be affected by their own personal version of common sense. But, unlike the abortion debate, there is also an objective element to the exercise because any argument which rests on a scientific proposition can be weighed by reference to the available scientific evidence. Of course history shows us that established scientific beliefs can be proved to be complete bunkum (until they are then proved to have been right all along, until they are again proved to be bunkum, until ... etc etc) so "objective" is an overstatement, but at least there is an empirical basis of assessment to add to our common sense.

The global warming debate would be just an amusing side-show if it were not for the predictions of plague and pestilence. Whether there is warming and whether man causes it or contributes to it in a significant way are neither here nor there unless there is a benefit to be achieved by preventing warming. The dire prognostications are essential for the topic to be worth examining at all by a layman.

I make no apologies for approaching the great global warming debate with a deeply sceptical mind. My scepticism is based on something I consider to be a matter of common sense, namely that nothing is worth doing if it does more harm than good. In order to assess whether more harm than good will result I have to decide how I value the position as it is now, then I have to decide how I value the position as it will be once the change has been made. My starting point is the belief that the development of the things that make life comfortable and which are now under attack was a great human achievement. For example, electricity is produced by CO2 emitting power stations to keep houses warm all year and fuels are produced from oil so that we can fly around the world and drive a car to visit friends and family when we want. These are things which were almost unimaginable a hundred years ago. So I start my examination by giving a high value to the comforts of life as it is lived today. This necessarily means that I require very cogent evidence in order to be persuaded that the clock should be turned back and these great comforts abandoned or ameliorated.

It is not, I think, unreasonable to assume that many others approach this issue as I do and that others have changed their position as I have changed mine. The simplicity of the greenhouse-effect theory is something which allows it to be readily understood and my initial reaction was that it is entirely plausible. But then I heard Saint Al of Gore say that the debate is over and the science is settled. Whatever area of science it addresses, such a statement is not only implausible it is patent nonsense. My version of common sense tells me that science is never settled on any issue ever, not once, not now, not in the past, not in the future, never at all, no, no, no. My version of common sense also tells me that conspiracy theories are to be treated like a fresh dog turd, they must be avoided if you wear nice shoes and left to dry in the sun until someone with a shovel consigns them to the dustbin. So conspiracy was out as an explanation for Saint Al's absurd statement, what then caused him to say it? My initial reaction was that he said it in order to stifle both debate and further scientific examination, for fear that he might be proved wrong which, in turn, caused me to enter the debate and look at the science.

As a lawyer by training and long experience I am satisfied that the best way to examine a proposition is to break it down into its constituent elements and examine each one in turn.
If a flaw is found in one element, it is then necessary to see how that flaw affects the other elements and whether the flaw undermines the substance of the proposition.

Saint Al puts forward a simple proposition with seven elements: (i) the earth's temperature is rising, (ii) a rise in CO2 in the atmosphere causes the earth's temperature to rise, (iii) no factor other than rising CO2 can explain the rise in temperature, (iv) human industrial activity causes a rise in CO2 levels in the atmosphere, (v) no other factor causes the rise in CO2 levels, (vi) continued human emission of CO2 will cause continued rises in temperature and (vii) the consequences are dire.

Just a few hours of googling proves beyond doubt that the debate is not over on any of these elements save, possibly, (iv). More than that, the central evidence relied on by Saint Al to support propositions (i), (iii) and (v) is open to such serious dispute that it cannot support his conclusions and the evidence supporting (vii) is in many respects pure speculation (the Stern Report, in particular, is the most absurd example of mashed logic and fanciful inference I have ever had the misfortune to read).

This does not mean his proposition is wrong, but it does mean we should not, in my opinion, adopt measures aimed at alleviating predicted dire consequences until the evidence in favour of the proposition is far more powerful than it is at the moment. I call that common sense.

3 comments:

Andrew said...

Agreed. And nicely explained.

TheFatBigot said...

I've received my first comment! I'm a real blogger. Whooppeeeeeeeeee.

fewqwer said...

(ii) is a vacuous certainty. The debate is over how much - the watermelons need a CO2 sensitivity of at least 3 C per doubling (IIRC) to suit their agenda, but it can't be too high, because then nothing could be done about it anyway.

To buy the whole AGW package, you need to put similar qualifiers on all those statements, and add further assumptions concerning the (self-evidently asinine) policies to 'tackle' it.

Even if you concede *all* of that, even the most passionate alarmists admit that their most extreme 'green' measures can only delay matters by a few decades. So you must then add assumptions about why that's worth it.

Interesting blog, by the way. Nice to read some (mainly) cautious argumentation for a change.