I recently came across a case out of the Court of Appeals of Texas (Royce Homes, L.P. v. Neel, 2005 Tex.App.LEXIS 1514) where the Court of Appeal overturned a jury’s determination of damages that was based on weak evidence from a construction defect expert. Although apparently well qualified, the expert simply estimated the costs of repairs based on his experience: he did not take any notes or measurements.
The court rejected the evidence as “ipse dixit” (sometimes spelled “ipse dexit”). The term is latin for “he said it himself”. The fallacy of logic is that by baldly asserting a state of affairs without evidence to support it sidesteps the argument. It is an assertion without proof. The fallacy is similar to an argument from authority.
My kids used to call me out on the use of ipse dixit all the time. When I made an assertion, they would ask “Why?” My usual, lazy, response was “Because I said so.”
Ipse dixit has been recognized as a problem in litigation, particularly in the area of expert evidence. In General Electric Co. et al. v. Joiner et ux, the U.S. Supreme Court recognized the problem of “opinion evidence which is connected to existing data only by the ipse dixit of an expert.”
The term has been used in several Canadian cases. For example, in Young v. Insurance Corp. of British Columbia, 2017 BCSC 2306 (CanLII), an expert gave evidence that damages in a motor vehicle accident were not caused by a sideswipe-type collision. At trial, the plaintiff objected to the evidence, with counsel asking “where is the science”. The court agreed, and rejected the evidence. The expert did not refer to his own assessment of sideswipe-type collisions. He did not refer to any studies or tests involving sideswipe-type collisions. As stated by the trial judge, “Instead, what we are left with is an exercise in ipse dixitism: it is so because I say it is so.”
In Lord’s Day Alliance fo Canada v. Regional Municipality of Peel et al., the issue was whether an exemption from Sunday closing by-laws was “essential for the maintenance or development of a tourist industry”. Town council said the exemption was essential, without citing any evidence. The Court of Appeal disagreed, holding that something more was required beyond council merely saying so. The legislation required proof that the exemption was essential, not just council deeming it to be essential.
In Lewis v. The King, 1949 CanLII 376 (QC CA), the Quebec Court of Appeal overturned a conviction for keeping a common betting house. In a concurring judgment, the appeal judge states that “there is no evidence, except the ipse dixit of the police officer, that the accused was the keeper of the place in which the search was made”.
In Ontario, Rule 53.03 of the Rules of Civil Procedure require that an expert report shall contain, inter alia, “The expert’s reasons for his or her opinion”.
As we head into elections, both here and in the US, keep your eyes open for ipse dixit.
Further, in litigation, be wary of ipse dixit evidence. Simply saying something is so does not make it so.
Make it a great weekend ahead. No ipse dixit. Provide proof.