Text: Any party expecting its program to be taken seriously as a left-of-center alternative to conservatism must surely propose one of two  Either it must promise to increase in the aggregate the quantity and quality of public services (and the taxes needed to pay for them), or else it must promise, within an unchanged total of taxes and spending, to redirect the flow of resources so that the less well-off get more.
Entailment: Each party must cater for the less well-off.
Contradiction: Each party must cater for the rich and famous.