The so-called “Half-Fee Lawsuit” is said to be a story related to the ancient Greek sophist Protagoras:
Protagoras was the founder of the Sophist school and one of the earliest fee-charging teachers in ancient Greece. A man named Euthlus once became Protagoras’s student to learn the art of litigation and defense, and the two signed a contract: when Euthlus enrolled, he would pay half the tuition fee; the other half would be paid in full when Euthlus won his first case after graduation. However, after graduating, Euthlus kept delaying and did not appear in court to argue cases for others, so the remaining half of the tuition fee had to be postponed again and again. Protagoras grew impatient waiting and decided to sue in court. In court, he said to Euthlus: “If you lose this case, then according to the court’s judgment, you should pay me the remaining half of the tuition fee; if you win this case, then according to the contract, you should pay me the remaining half of the tuition fee, because this is your first victory in court. In short, whether you win or lose, you must pay me the remaining half of the tuition fee.”
But Euthlus struck back: “On the contrary, if I lose this case, then according to the contract, I do not need to pay the remaining half of the tuition fee, because I did not win my first case in court; if I win this case, then according to the court’s judgment, I also do not need to pay the remaining half of the tuition fee. In short, whether I win or lose, I do not need to pay the remaining half of the tuition fee.”
In response to this story, many people have raised the following question: As a judge, how should one rule?
I believe that in many related discussions, this question has been unnecessarily complicated. Of course, it may perhaps be appropriately complicated so that some variant of it becomes a genuine paradox; but as for the original statement of the question itself, viewed from the perspective of the judge, there is no need to fall into a dilemma.
First, it is obvious that in the course of the judge’s ruling, the result of the ruling has not yet occurred. Whether the judge rules that the teacher wins or the student wins, that happens only after the judgment has been delivered.
Consider the obviously mistaken theory below:
—Because the seventeen-year-old defendant will come of age next year, which is certain, he should now be sentenced according to the standard for adults.
—Going further, because everyone will inevitably die, and the dead do not need to go to prison, the defendant does not need to go to prison…
Such judgments are obviously laughable. Something that will happen in the future, even if it is inevitable and foreseeable, cannot be lightly used as the basis for a present judgment. Likewise, for the judge, the event “Euthlus wins his first case after graduation” cannot possibly occur before the ruling is made—even if the judge can foresee that it must happen. Therefore, when the judge renders a decision, the contractual condition for paying the tuition fee, namely “Euthlus wins his first case after graduation,” has not occurred. Given this, the judge is fully justified in ruling that Euthlus need not pay the tuition fee!
But Protagoras need not be discouraged; he could simply bring a second lawsuit and make the same demand again. Note that a court’s judgment is not permanent, which is also quite obvious: for example, if a person is found not guilty of murder and then later kills someone, the court can of course find him guilty in a new lawsuit. If new events occur between the judgments of two lawsuits, they can of course affect the outcome of the second case, making it entirely different from the first. Here, the new event between the two lawsuits initiated by Protagoras is precisely: “Euthlus won the first case.” In this way, when the second case is tried, the contractual condition for paying the tuition fee—“Euthlus wins his first case after graduation”—has become an already existing fact and can be used as the basis for judgment. Given this, the judge is fully justified in ruling that Euthlus must pay the tuition fee!
Of course, this second lawsuit seems redundant; why not simply determine the final result in the first judgment? If both sides were reasonable people, and the judge explained the above reasoning, then in any case Euthlus would have to pay, so it might as well be settled out of court to avoid unnecessary litigation. But if Euthlus insists on being pedantic, then in order to convince him through rigorous logic, one can only adopt the above seemingly superfluous measure; otherwise it would not be enough to make Euthlus truly convinced.
The problem is that in everyday thinking, there is no “judge” intervening at every moment to render a decision. The intervention of a “judge” actually signifies some interruption in the thought process, because the judge considers only established facts and generally does not rely on future events; including the outcome about to be reached in the judgment cannot simply be turned around and become the basis for that judgment. But in everyday thinking, the absence of a “judge” means that continuous thought has no clear gaps to follow, so that many “results of judgment” can be turned back and used again as “bases for judgment,” that is, one can always continue to reason on the basis of the result of reasoning. In most cases this causes no difficulty. But once one encounters problems in which the result of reasoning is closely related to the process of reasoning—for instance, when the presuppositions of reasoning are directly linked to the process of reasoning (just as a contract is directly linked to a trial)—people will, consciously or unconsciously, use “two judgments” in the process of reasoning, yet when the result is obtained, treat it as “one judgment”; just as, if one could reach the same conclusion as two judgments by means of only one judgment, that would not convince Euthlus. Likewise, those reasonings may also produce perplexing conclusions. For example, the “surprise drill paradox” I analyzed earlier, and especially its so-called variant, the “Hollis paradox,” all seem to imply a similar problem. What we need to think about is this: is the practice of feeding the conclusion of a piece of reasoning back into the basis for further reasoning always appropriate?
July 11, 2006
Translated from the Chinese original with AI assistance. The original text is authoritative.
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