RALEIGH – To have a useful debate – be it about politics, religion, or where to get a really good chili dog – the participants must first agree on the definition of the relevant terms. Failure to embrace common definitions is often the real cause of seemingly intractable, and often pointlessly vitriolic, controversies.

Set aside politics and religion for a moment and consider the question of where to get a really good chili dog (which is, actually, a quasi-religious question for some of us). What does “really good” mean in this context? Sheer taste? Taste at a set price? And does the term “chili dog” embrace all cylindrical precooked sausages, or just franks, or just the subset of beef franks? Is it all about the chili, or are other available condiments to be considered in evaluating the options?

All argumentation begins with definition. The other two parts of a logical proposition, the premises and the proof, rest on the initial definition of terms. You need all three. Many famous arguments have had true premises, and conclusions derived properly from those premises, and still been invalid because of a faulty definition of terms. Examples would include some of Zeno’s paradoxes about the impossibility of completed motion and the notion that the existence of evil disproves the existence of God (the Wikipedia entry on this one is pretty good). Faulty definitions yield faulty conclusions, often with the result that observers come away thinking that the argument in question sounds logically proved and yet seems wrong. That’s your inner bulldog of common sense sniffing sophistry and letting out a yelp. If logic tells you that my hand can never reach your tummy because of an infinite number of points on the line between us, and yet you are writhing in laughter as I tickle you, you can be sure that your definitions of time and space are questionable (as is my propriety).

In modern political debate, the problem of definition plagues claims of justice and injustice. From Socrates to John Rawls, philosophers and their readers have sought to define justice. Some defined justice as the outcome of a just process, by which they mean a process that respects everyone’s equal, procedural rights. Other defined justice as determined by the specific outcome itself, whether it apportioned goods equally or according to some other criteria they favored, such as merit, identity, or adequacy.

Rawls, the late Harvard professor, sought to revive and transform the social contract theory of John Locke & Co. in order to justify 20th century liberalism. He argued that in a hypothetical social contract, bargained among every human being who would ever live before anyone ever did, there would be unanimous agreement on two main principles: 1) individuals should have the maximum amount of liberty to think and do what they wish, without coercive constraint, except when 2) inequalities of wealth or status that would result could not be justified as benefiting the least-well-off member of society. In theory, it sounded like Rawls was elevating liberty as a guiding principle of social organization. In practice, though, Rawls was arguing that justice required constant coercive intervention to redress differences among individuals, since the wealthy and successful would have the burden of proof of showing that their continued wealth or success benefited the poor more than redistribution would.

There were many problems with Rawls’ reasoning – for example, given that behind his “veil of ignorance” no parties to the social contract enjoyed a nationality, his principles actually mandated a sustained transfer of income not from rich to poor Americans but from all Americans to even-poorer Haitians, not exactly what New Dealers and Great Society types had in mind – but the more fundamental problem was of definition. Rawls had defined justice as “fairness” without any relationship to basic human rights and responsibilities. His definition of justice, in other words, excluded any natural or supernatural conception of morality. As critics subsequently pointed out, this so badly miscast the debate about justice that it could be said to be “just” not only for wealthy individuals to be forced by the state to surrender their possessions to the poor, but also for the beautiful to be compensated or even forced by the state to surrender their bodies to the ugly. Each policy could be argued as a kind of amoral, pre-natal insurance against losing life’s lottery. If theft could be just, in other words, so could tax-funded prostitution and rape.

Faulty definitions yield faulty conclusions. Oh, and the best place to get really good chili dogs is Nathan’s.

Hood is president of the John Locke Foundation.