A Note on the Pure Theory of Consumer's Behaviour: An Addendum

IN the February issue of this journal I suggested that the theory of consumer's behaviour could be founded on three postulates: (I) that the amount demanded of each commodity be a single valued function of all prices and income; (2) that this function be homogeneous of order zero in the variables prices and income, i.e., the simultaneous doubling of all prices and income must leave all quantities demanded invariant; (3) that the individual always behaves consistently in the sense that he should never prefer a first batch of goods to a second at the same time that he prefers the second to the first. Preference was defined in a special sense so that the mathematical statement of the third postulate was