We are likely to remember the case today because of a comment (which he later regretted) that Supreme Court Justice Potter Stewart made in stating his concurring opinion:
I shall not attempt further to define the kind of material I understand to be embraced within that shorthand description (of pornography), and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in that case is not that.
So, why is this case interesting, and how can a philosopher make a useful contribution?
The first step is to cast information as a logically sound argument. Capturing Stewart’s comments in argument form yields this:
1. There is a method M such that applying M is sufficient to determine whether or not an X falls under concept C without having to define in the general case whether or not something falls under C.
2. “I know it when I see it” is sufficient to determine whether or not Malle’s film falls under concept C, “pornography,” without having to define in the general case whether or not a film falls under concept C.
3. I have applied M and have determined that Malle’s film does not fall under concept C.Therefore,
4. I decide in favor of the plaintiff.
Stewart’s comments imply premises 2 and 3, and we know he decided in favor of the plaintiff.
What about premise 1? Why is it needed? It is needed because, without something true in the general case, the argument is stuck justifying premise 2, which is not obviously true. With 2 asserted as an instance of 1, the argument can proceed. Did Stewart realize premise 1 is needed? I have no idea. Let’s give it to him anyway.
So, is the argument logically correct?
No. Something is missing. What is missing is that “I know it when I see it” is a method with M-like properties. That is, what is missing is that “I know it when I see it” is, with nothing more, sufficient to determine whether or not any X falls under any concept C without having to define in the general case whether or not something falls under C. Generalizing from a case that (conveniently) happens to fit, like Malle’s film, is an elementary fallacy. (Climate change hucksters commit it routinely. Without fallacious arguments, they’d have no arguments at all.)
So, is “I know it when I see it” a method with M-like properties? Not really.
For example, how can someone tell whether or not a function is differentiable at a point without being able to define relevant concepts of calculus? Closer to Stewart’s home, how can someone tell whether or not a piece of evidence is admissible in court without being able to define the difference between evidence that is admissible and evidence that is not? “I know it when I see it” won’t do in the general case at all. Perhaps that is why Stewart later regretted his comment.
In short, the argument is unsound because the premise needed for validity is false.
Stewart would have been able to stay out of trouble had he left well enough alone after his first sentence. Instead of writing noncommittally, “nevertheless, it seems to me that the motion picture in this case does not fit that shorthand description (of pornography),” he went on to open a can of worms and flunked logic by continuing with his “I know it when I see it” analysis:
(a) He provided judges with a criterion by which they could tell “whether or not a specific X falls under concept C.”
(b) He provided a subjective criterion, which he believed was appropriate as well as adequate.
(c) He invited his brethren in black robes to use subjective criteria to adjudicate cases before them, civil or criminal, as long as they believed they were appropriate as well as adequate.
Point (a) is not in principle problematic. A criterion can be helpful, and may even be required, to convince those affected by a decision that it’s the right decision, especially when a controversial issue is at stake.
As to (b) and (c), I lost track of the number of times our judicial system (ha ha) charged President Trump with violations of law based on subjective (made-up?) criteria, all in an effort to block agenda items he was elected to carry out. Deep Staters “knew it when they saw it” as soon as they were able to “find the man,” as Lavrentiy Beria advised—which is also how J6 patriots got thrown into the DC gulag, where they languished far too long. Stewart opened a Pandora’s Box, not merely a can of worms.
To conclude on a positive note, Stewart’s comment leads us to a philosophically interesting problem. We start by simplifying premise 1 and adding its converse.
1*. Person X can tell whether or not a specific Y falls under concept Z only ifperson X can already define in the general case what kinds of things fall under concept Z.
1**. Person X can define in the general case what kinds of things fall under concept Z only if person X can already tell whether or not a specific Y falls under concept Z.
That is, how can I tell whether or not something is an “it” without already having a general idea of what kinds of things are “it”? On the other hand, how can I arrive at a general idea of what kinds of things are “it” without already being able to tell whether or not something is an “it”?
If 1* and 1** are both true, a vicious circle follows. Now what?
Welcome to The Problem of the Criterion. It has implications for fields of inquiry where criteria are used to define key concepts and methods are supplied to decide the application of concepts, including jurisprudence, science, mathematics, religion (that too), morality, and even philosophy itself. Plato anticipated the problem in Meno. Sextus Empiricus and Michel de Montaigne followed centuries later. Roderick Chisholm at long last gave the problem deserved prominence in his 1973 Aquinas Lecture. A survey article by Kevin McCain reviews the issues. (If you’re still interested, you can read my take in “Chisholm’s Obsession,” forthcoming in Logos & Episteme, where I argue that mathematical logic holds the key to the problem.)
Stewart got in way over his head.