Life, Liberty, etc. ________________________________ Published 11/12/01 in the Connecticut Law Tribune
What Logic? By Martha A. Dean ________________________________
Today, in contrast with preceding centuries, few lawyers have formally studied Logic. Yet, it would seem that this is something lawyers would (and should) have studied, perhaps in law school. There are two branches of logic: formal logic and material logic. Formal logic is interested in the structure of reasoning -- the method of deriving one truth from another. How often do you hear arguments such as: “All attorneys went to law school. Jane went to law school. Therefore she is an attorney.” Is this a valid deductive argument? No, but inverting a valid syllogism, thereby making it invalid, is one of the most common logical errors made. Where the subject matter is familiar, as in this case, most of us will recognize the error intuitively: many law school graduates do not become attorneys. But if the subject were one about which we know little, intuition would not be enough. In a valid deductive argument, the truth of the premises guarantees the truth of the conclusion (e.g. all lemons are yellow; A is a lemon; therefore A is yellow). Thus, while it must be true that if all attorneys went to law school and John is an attorney, that John went to law school, the reverse (that John went to law school therefore he is an attorney) is not necessarily true. Material logic, on the other hand, is concerned with the content of argumentation -- the truth of the terms and the propositions in an argument. The argument highlighted in the following case is invalid because of the falseness of its premise. A man purchases a house for $600,000 with what is represented to be a functioning septic system. Immediately thereafter he discovers a septic system failure and learns from the repairman that the seller knew of this. In the suit for damages, the defense claims that the buyers could not have suffered the $20,000 in damages that they allege (for a new system) since they, ultimately, made a profit on the house by later reselling it for $800,000. The buyer/plaintiff’s attorney seeks to prevent the jury from hearing testimony as to the resale price on the grounds that it was irrelevant and highly prejudicial. The judge allows the testimony in. The jury finds for the buyer/plaintiff but awards no damages. Were the judge and jury correct to conclude that the resale price was relevant? An unscientific sampling of attorneys’ opinions on this reveals that most think the resale price is relevant. Yet, it is not, and this is why: in Scenario A the house has a functioning septic, and the buyer/plaintiff realizes a $200,000 profit upon reselling the $600,000 house for $800,000. In Scenario B, the house has a failed septic that must be repaired for $20,000, leading to only a $180,000 profit upon reselling the $600,000 house for $800,000. The fact that the buyer/plaintiff would have been $20,000 better off had there been a functioning septic -- as promised -- is true no matter how great or small the resale price. This makes the resale price irrelevant. The argument to the contrary goes something like this : “Anyone who makes a profit has not suffered a loss, so if a profit is made, then a loss was not suffered.” While superficially logical (it’s form is fine), it is invalid because the premise is untrue. It may seem obvious to
some that a short term loss does not foreclose a long term profit, and that comparing a short term loss suffered at the hands of a third partyâ€™s unlawful act (here, the fraud) should not be contrasted with whether the injured party makes a profit in some unrelated business endeavor (here, buying and selling a house). But it is clearly not obvious to all. The result in this case is that the buyer/plaintiff will not be compensated for the $20,000 loss. In what has become an atmosphere of relativism in many law schools, to say that there are objectively sound and unsound ways of thinking might seem controversial. But the formal study of Logic is the age-old study of the science of correct and incorrect reasoning. Throughout history, training in Logic has been an essential part of the training for lawyers, judges and legal scholars. Perhaps it is time to turn away from the now popular â€œLaw & ...â€? courses that teach policy ends and refocus on teaching sound thinking. Some things -- though certainly not all -are true or false without regard to social preferences, and it is critical to the integrity of the profession that those who practice and teach law understand this.
Published on Aug 26, 2010
________________________________ Published 11/12/01 in the Connecticut Law Tribune By Martha A. Dean ________________________________ Life,...