I'm currently making a start on wading through a popular economics textbook by Greg Mankiw. Mankiw is big on economics as science, and big on distinguishing positive, testable statements from normative ones. From his preface:

Economics combines the virtues of politics and science. It is, truly, a social science. Its subject matter is society - how people choose to lead their lives and how they interact with one another. But it approaches the subject with the dispassion of a science. By bringing the methods of science to the questions of politics, economics tries to make progress on the challenges that all societies face.

A little later (after expounding on the comparisons between scientific and economic discoveries) Mankiw gives a section entitled 'why economists disagree'. His first reason: differences in scientific judgements. Citing the examples of heliocentrism and more recent arguments over global warming, he says:

Economists often disagree for the same reason. Economics is a young science and there is still much to be learned.

Ummmmm. OK. 'Differences in values' then makes an appearance. His example has Peter and Paul on $50,000 and $10,000. How much should they be taxed? Should it depend on whether its inherited wealth? On whether one works much harder than the other, etc, and concludes:

Perfecting the science of economics will not tell us whether it is Peter or Paul who pays too much.

But Mankiw's third reason is the most interesting for me: he lists 'ten propositions about economic policy' that, supposedly, illustrate how much economists share a consensus. I won't list them all, but they range from 'a ceiling on rents reduces the quality and quantity of housing available' (supported by 93% of respondents) to 'effluent taxes and marketable pollution permits represent a better approach to pollution control than imposition of pollution ceilings' (78%) with a range of percentages in between.

Its tempting to scoff, but that would be leftie laziness. (Though perhaps resisting the temptation to scoff is how it starts. Perhaps Mankiw is Emperor Palpatine to my Anakin...)

Ahem, anyway: can a discipline with this level of disagreement lay claim to being scientific? If anyone in an engineering firm attempted to use a theory they were 93% sure of, let alone 78%, they'd quickly find themselves on the dole. But of course they would be able to test their models in ways economists can only dream about.

When it comes to something like global warming, there's a lot less certainty. That's at least in part because the whole caboodle of global warming theory has to wait to be corroborated or falsified, and even if and when observations match predictions, there are so many other factors that could have been the cause... hmm, a little like economics.

But not very much. I'm not sure if this is true, but I believe that all climate scientists would support the statement: increased concentrations of CO2 in the atmosphere will lead to an increase in average global temperature. So do economists have such well-supported theories? That's a difficult call. You might say: an interruption in the supply of a product will lead to increased demand, which will lead to increased prices. Its hard to say where this comes in a discipline's hierarchy of dogma; does it compare to the CO2 hypothesis - or to something so fundamental as to be not worth surveying, such as the first and second laws of thermodynamics? (Though note that there seems to be plenty of argument about any further thermodynamics laws...)

The peculiar blindspot of economics, and its embodiment in institutions like the World Bank, is that they never apply their theories to themselves. I reckon this is a direct result of the claim to scientific-y-ness. Mankiw can quite happily note that government should be treated with suspicion: they're just rational, self-interested individuals after all, who'll make policy that will benefit them and their cronies. But the thousands of ecomomists at the IMF, World Bank, Department of Treasury, of Labour, of Justice, at the Federal Reserve - they're all dispassionate scientists, presenting politicians with the cold, neutral curves upon which they may place their values...?

The World Bank's writing is particularly unreal: page upon page extolling the virtues of de-centralisation, and setting up fields of competing institutions to see which ones will live or die in the great population ecology of World Bank experiments in the Third World. Except, of course, for the World Bank - which somehow exists outside and above the world they make policy for. Presumably it is also staffed with super-human, Platonic guardians who think only of the interests of the poor, and are immune to the influence of either their funding streams or their purse-string holders.

So at what point should the economist stop arguing that her theories are immutable science? Maybe she shouldn't - but should she accept that the only way to sell those theories is through the democratic process, like everyone else? So the World Bank has to compete with two or three other International Financial Institutions that they can best serve the interests of African countries - or they don't get that country's slice of the aid pie.

This could wander off into a whole new topic: political and economic consensuses have come and go over the last couple of centuries, with themes re-emerging and sinking under again. I think I'd have to conclude that economics can be pseudo-science at best, because its theories are not falsifiable enough. As the World Bank says: if a country has suffered disappointing growth, that 'should not be attributed to the failure of reforms' but rather the 'muting' effect of weak infrastructure [WB Development Report 00/01: 'Attacking Poverty']; how can African farmers respond to market signals if the Bank hasn't yet build the the infrastructure for those signals to transmit? Ah ha ha. The theory is sound: the world is wrong. So we will change the world.

But there's more mileage in the comparison between economics and climate change science, I reckon.

On a different note, government scientists have shown that putting bromide in the water supply would decrease the chance of civil unrest, and lead to a 75% drop in alcohol-related incidents at the weekend - saving the NHS and the police force several hundreds of millions. (Not really, I just made that up.) I only mention it because while I was checking what bromide did, I discovered via Wikipedia that it was first used to treat epilepsy. At the time, in the 1850s, epilepsy was thought to be caused by masturbation. The effect of bromide on sexual drive confirmed this theory. I wonder, what else did scientists at the time do to corrobarate it? It seems an eminently suitable theory for self-testing. I can just imagine the presentation at the Royal Medical Society... "despite the best efforts of myself and my trusty lab assistant Derek, I have yet to confirm..."

Oo, wouldn't it be fun to try and start a rumour that the government - or maybe a cabal of US and UK secret agents, working with the government - are planning to do just that? Not test the masturbation / epilepsy theory, the other thing. Ah ha ha, I can see the headline:

US, UK secret service agents in underground orgy club scandal: 'we were just testing a theory', says chief...