Conventional economics got set in its ways long before neuroscientists discovered something that helps explain why the decisions consumers and business people make are often far from rational: our brains have two different, and sometimes competing, systems for deciding things.
Psychologists call it system one and system two thinking. System one is our intuitive system of processing information. It's fast, automatic, effortless, implicit and emotional. It's controlled by the earlier, more primitive part of our brain. It's highly efficient and is thus the most appropriate tool for the majority of mundane decisions we make every day.
By contrast, system two thinking is slower, conscious, effortful, explicit and more logical. It's controlled by the more recent, frontal part of our brain. When we weigh the costs and benefits of alternative courses of action in a systematic and organised manner, we're engaged in system two thinking.
In the hands of scholars who study behavioural ethics - such as Max Bazerman and Ann Tenbrunsel, the authors of Blind Spots - system one is seen as our "want-self" and system two as our "should-self". Almost all of us regard ourselves as ethical. Before decisions arise our should-selves think "I should behave ethically, therefore I will".
When we're looking back on decisions, our should-selves think: "I should have behaved ethically, therefore I did." Trouble is, when the decision is actually being made, our want-selves take over and we often do things that ignore the ethical implications of our actions.
The task for behavioural ethicists, therefore, is to help us find strategies that allow our should-selves to dominate our want-selves. In another context, psychologists say we have different systems for wanting things and liking things. So some of the stuff we really want, and spend a lot of time pursuing, doesn't give us as much satisfaction as we thought it would once we've got it.
This explains why children will spend weeks nagging parents to buy them a guitar or a pet but quickly lose interest once they have it.
It also explains a lot of futile adult behaviour. I suspect our two thinking systems explain the paradox of advertising. I'm not influenced by all the advertising I see, but a lot of people are. Do you think that, too? Trouble is, most people think it.
If it's true, just who are the dummies that fall for advertising? And how come so many businesses spend millions on advertising, convinced it's money well spent?
I think all of us are more susceptible to advertising than we realise. Most advertising is designed to appeal to our emotions and instincts, not our intellect. In other words, it's aimed at our unconscious, system one decision-maker and we're not conscious of the way it affects the choices we make. Meanwhile, our conscious, reasoning system two brain is unimpressed by the illogical connections we see in ads.
I'm sure they're not all Robinson Crusoe, but economists often show signs of having two-track minds. They believe certain things intellectually, but these beliefs don't seem to have the effect on their behaviour that you'd expect.
For instance, when you criticise their model for its absurd assumption that people are always rational - carefully calculating and self-interested - they'll tell you they don't actually believe people are rational; that's just a convenient assumption needed to get the model going.
But then they'll argue vigorously for propositions that come from the model, oblivious to the way those propositions rest on the assumption that people are indeed rational in all they decide.
Or, take the exaltation of gross domestic product. When you argue that GDP is a poor measure of national well-being and point out its various limitations, economists will agree. But that won't stop them continuing to treat GDP is though it's the one thing that matters.
One of the most ubiquitous problems in daily life - and thus in the economy - is one the economists' model assumes away: achieving self-control. We need to control our natural urges to eat too much, to smoke, to drink too much, to gamble too much, spend too much, watch too much television, get too little exercise and even to work too much.
Here, again, we seem to have two selves at work: an unconscious self that's emotional and shortsighted and a conscious self that's reasoning and farsighted. We have trouble controlling ourselves in circumstances where the benefits are immediate and certain, whereas the costs are longer-term and uncertain.
When you come home tired from work, for instance, the benefits of slumping in front of the telly are immediate, whereas the costs - feeling tired the next day; looking back on your life and realising you could have done a lot better if you'd got off your backside and played a bit of sport, sought a further qualification at tech, studied harder for exams, spent more time talking to your children, etc - are not so clear-cut.
Similarly, the reward from eating food is instant whereas the costs of overeating are uncertain and far off: being regarded as physically unattractive, becoming obese, becoming a diabetic, dying younger, etc.
As everyone who has tried to diet, give up smoking, control their drinking, save or get on top of their credit card debt knows, it's hard to achieve the self-control our conscious, future-selves want us to achieve.
People have developed many strategies to help their future-selves gain control over their immediate-selves, including pre-commitment devices - similar to those proposed by the Productivity Commission to assist problem gamblers.
Economics will become a more useful discipline when its practitioners catch up with developments in neuroscience and offer us solutions to common behaviour problems it now assumes away.
