It is pretty much understood that the basic orthodox labour market model is agnostic insofar as income and substitution effects are concerned. If for example real wages increase workers may choose to work less because they can consume more leisure with less hours of work or workers may work more hours because the opportunity cost of leisure has gone up. Which effects dominate workers’ incentives are not predetermined by the standard labour market model.
Implicitly, however, we can glean what mainstream economics tends to think are the incentives facing different classes (economic classes that is) of workers. In Mankiw’s recently ridiculed here, here, here and here article in the NYT, he argued the impact of a tax increase on the economic class of ‘workers’ at the top of remuneration scale was a decrease in the real wage which would be met by a substitution of more leisure for less work as the opportunity cost of leisure had been cheapened by the tax increase. Simply stated this class of workers would respond to a decline in their real wage with a union strike like reaction.
So far so good. I do not imagine it inconceivable that those workers with compensation packages that put them in the top 1% of income earners could choose to work less hours if they were faced with a wage cut with one important caveat. They would have to have the type of job which allowed them to control their hours of work and or have sufficient means to withdrawal from the labour market altogether aka independently wealthy. For example, an NHL hockey player cannot say to his coach I am playing one less game a year because of the increase in marginal tax rates; although he might try to make the team offset the tax increase with a higher salary. Thank god for salary caps.
However, when we turn to lower classes of workers we find that Mankiw argues that income effects dominate their incentives. In his introductory textbook he has the following to say about unemployment insurance:
So here Mankiw argues that workers respond according to income effects. Lowering unemployment insurance replacement rates would decrease unemployment because workers would have a greater income incentive to take a job.
What, therefore, accounts for the different reactions between these two classes of workers? Why that is will increased taxes on the rich (a decrease in the real wage) lead to a withdrawal from the labour market but a decrease in unemployment benefits (again a decrease in the real wage) increase the supply of labour. The answer of course is that most classes of workers are not independently wealthy and do not meaningfully control their hours of work. Workers have to work and outside of access to unemployment benefits they do not have the option of defecting from paid labour markets. Therefore whether income or substitution effects predominate is largely a function of class. Most classes of workers save for those at the very top respond to a decreased real wage either by seeking more hours of work through one of three ways: overtime, a second job or telling their teenager to go get a job and pay their own cell phone bill.
It is interesting that Karl Marx (well Smith too in some respects) were the first to recognize the differences between classes of workers what we once called proletarians and the bourgeoisie. But that is for another post.