Many thanks to A2 student Lara Hodgson for this superb cake that the class enjoyed this morning. Remember that the standard Keynesian consumption function is written as follows:
C = a + c (Yd) – where:
- C = total consumer spending
- a = is autonomous spending
- c (Yd) = the propensity to spend out of disposable income
Autonomous spending (a) is consumption which does not depend on the level of income. For example people can fund some of their spending by using their savings or by borrowing money from banks and other lenders. A change in autonomous spending would in fact cause a shift in the consumption function leading to a change in consumer demand at all levels of income. The key to understanding how a rise in disposable income affects household spending is to understand the concept of the marginal propensity to consume (mpc). The marginal propensity to consume is the change in consumer spending arising from a change in disposable income. The higher the mpc the steeper the gradient of the consumption function line. As you can imagine the consumption of cake was fairly rapid.
In 1776 Scottish economist Adam Smith talked of the economy as the invisible hand. Here he emphasized the self-regulating nature of the economy as individuals, firms and companies independently seek to maximize their gain which may produce the best outcome for society as a whole. The capitalist systems seems to rely more on the relentless growth of consumer spending and, although it can lead to dramatic improvements in standard of living, it does require people to become resolutely addicted to products/services and be prepared to get into significant debt.
Today, an economy is a much more intricate machine which aims to allocate scarce resources to satisfy the utility of economic agents such as individuals, firms and government. The dominant model for many years has been “Dynamic Stochastic General Equilibrium” (DSGE) and it takes all the characteristics of an individual (this person is typically called the representative agent) which is then cloned and taken to represent the typical person in an economy.
Therefore it assumes that all individuals and firms have identical needs and wants which they pursue with total self-interest and complete knowledge of what they desire. DSGE also takes into account the impact of shocks like oil prices, technological change, interest rates, taxation etc. However a couple of areas that it doesn’t represent accurately is the financial sector and the instability of markets – booms and slumps. A new task will be to include the banking sector into the models as macroeconomists assumed it to be a screen between savers and borrowers rather than profit orientated organisations prepared to take big risks with increased leverage and sub-prime lending. For example as house prices increase banks are willing to lend more money to speculators who bid up the price above what is the fundamental value. The opposite applies if banks become more risk adverse and marginal buyers are forced out of the market causing prices to drop. By representing the financial sector in an economic model you go some way to help solve the major problem with DSGE and other models in that they are useful only if they are not unsettled by external factors like a banking crisis.
Keynes said “If economists could manage to get themselves thought of as humble, competent people, on a level with dentists, that would be splendid!”. To achieve this there needs to be structural reform in the discipline.
An emerging field called agent-based modelling has grabbed the attention of some economists. This is where large amounts of data is collected from individuals who are unique to each other in they have different motives and actions in the market place. The behaviour of these individuals overlap and interact which generate predictions through a messy process but similar to what happens in real life, unlike DSGE and the clean old-fashioned macroeconomic models. Agent-based modeling has also shown promise in other disciplines like Physics and involve real-world problems. The example used by John Lanchester (New York Times magazine) is how Brazil nuts seem to end up towards the top of the mixed-nut package and nut research has since found real-life applications in industries such as pharmaceuticals and manufacturing.
With a better sense of what is influencing behaviour in the economy, economists might become less blinkered by their own theory, and better able to foresee the next crisis. Meanwhile, they would be wise to repeat (daily) the words: “My model is a model, not the model.”
Macroeconomic models need to be adapted to take account of the events of the last 20 years. For so long typical macro model has been DSGE but as yet no model includes the impact of recessions and the eighty-year depressions. Economics failed to predict or prevent the GFC and this was based on conceptual faults which included a refusal to engage with the role of the banking and finance system in the economy.
Dani Rodrik of Harvard University splits economists into two camps: hedgehogs and foxes.
Hedgehogs take a single idea and apply it to every problem they come across.
Foxes have no grand vision but lots of seemingly contradictory views, as they tailor their conclusions to the situation.
Maybe more fox like behaviour is needed.