I turn now to the demand law. The traditional derivation of market demand hinges on the idea of constancy of the “mind in itself”.

This belief is the crucial assumption in justifying the universality of the individual utility function. Individual optimization can hold if, and only if, this assumption is retained.

However, the constancy of the “mind in itself” is merely a metaphysical presumption taken as irrefutable where “free will” is ubiquitous. In reality, there is considerable evidence to refute the demand law. For example, income effects cause so-called Giffen effects. As Mizuno et al. (2010) and Mizuno and Watanabe (2010) showed, however, even in online markets, which can be considered to fulfill “perfect competitiveness”, customers do not follow the demand law. They do not necessarily increase demand when the price is lowered. Giffen’s discovery, made at the end of the nineteenth century, is still valid today.

2.2.1

More on the topic I turn now to the demand law. The traditional derivation of market demand hinges on the idea of constancy of the “mind in itself”.:

1. I turn now to the demand law. The traditional derivation of market demand hinges on the idea of constancy of the “mind in itself”.