It’s April Fools Day—a day of jokey trickery, of practical jokes.
Unlike in year’s past (2025, 2024, 2023, 2022…) I have no jokey post. Depending on how you feel about that I’d like to say either “I’m sorry” or “You’re welcome.”
I thought about soliciting examples of great practical jokes in philosophy, but of course that raised the question: “What is a practical joke?” or “What is it to make a practical joke?”
It does not appear that much philosophy has been written about practical jokes. One recent exception is “Practical Joking, Lying, and Denying” by Emanuel Viebahn (Hamburg) in The Philosophical Quarterly (ungated version here). While insightful on the relationship between deception and practical joking, it does not offer an answer to our definitional question.

So let’s be good philosophers and define our terms. Fill in the blank in
X is a practical joke if and only if _______________
or in
A makes a practical joke on B when _______________
(or, if you prefer a different definition structure, go with that).
With luck, we’ll get some good suggestions in the comments, counterexample them into shape, and see which one is the best. If there is a clear winner, I’ll update this post with the definition, giving credit to its author, such that afterwards your name will forever be associated with practical jokes. Is that a prize? (“What is a prize?”…)
Related: “A Parody Issue of Mind… from 118 Years ago“


Why not?!
A makes a practical joke on B iff:
Practical jokes, being jokes, can be distinguished from pranks which need not be intended to be humorous (though many pranks are also practical jokes, some pranks are intended only to annoy). It may be best to say that pranks are a subspecies of practical jokes that are usually not intended to include B on the joke (if A pranks B then B isn’t “in” on the joke even after it’s occurred).
For the record, I assumed that the World Philosophy Rankings post, made today, was intended as a joke post.
If Another Justin is right, then I think this post a counterexample. I don’t think it’s making use of physical space, except in the super trivial sense in which all jokes do when communicated.
For a similar counterexample, see We’re Introducing Advertising! (Which, I hate to admit, I fell for earlier today.)
I think this characterization is too narrow. Consider: A may wish to elicit, via their joke, an emotion from a third party C (and perhaps we might even consider cases where C is identified with A), while they care not at all about the inner world of B.
…aka, a “mean spirited” practical joke, which tends also to be a prank.
“X is a practical joke if and only if _______________“
I thought you weren’t going to make a jokey post?? 😂
Shhhhhhhhh
There’s a fair bit on humour, including jokes, going back at least 400 years (I’ve seen mention of a medieval Italian pamphlet, but I never managed to track it down). I don’t recall anything about practical jokes, but I might not be remembering correctly.
If anything, though, surely they’re best explained by the superiority theory.
Practical jokes differ from theoretical jokes, in that they are not drawn from universal first principles, but rather from humorous particulars.
In theory, there’s no difference between a practical and theoretical joke. But in practice, there is.
A practical joke is just a joke which is practical.
(Forthcoming in Phil Review)
Brand Blanshard thought C. E. M. Joad was confused about what practical jokes are.
According to Blanshard, while staying at the home of Sir James A. H. Murray, editor of the Oxford English Dictionary, C. E. M. Joad “engaged in playing on this household a series of ‘practical jokes.’ [Blanshard’s scare quotes] … One of them was to upset a large bottle of mucilage over Sir James’s work table, gumming together masses of the invaluable slips of paper with which [Murray] was working.” (“Autobiography of Brand Blanshard,” in The Philosophy of Brand Blanshard, ed. Paul Arthur Schilpp, 1980, p. 63) Another example: Joad put Brussels sprouts in a child’s toy in Murray’s home, “producing a stench whose source it was almost impossible to locate.”
Blanshard again expresses doubt about Joad’s understanding of the term when he writes of Joad’s “penchant for what he insisted on calling practical jokes” (p. 63). Blanshard then describes Joad’s practice of fare evasion on commuter trains. The rail company eventually caught him. Joad’s practical joke or prank or whatever it was ended with Joad’s appearing in court, where he was fined. Blanshard concludes the tale by saying, “In England, much is tolerated in public figures, but this sort of thing is not, and it put an end abruptly to Joad’s public career.”
I shall write a book called “Critique of Practical Jokes,” one of three critiques alongside “Critique of Pure Jokes,” and “Critique of Humorous Judgment.”
X is a practical joke if and only if the perpetrator persuaded his victims to try to define the meaning of the term ‘practical joke’.
Or to click on a button for an example of a practical joke.
Thanks for the pointer to the paper, Justin!
I still don’t know how to answer the definitional question, but I find Moira Marsh’s proposal in her book Practically Joking interesting:
A practical joke is a scripted, unilateral play performance involving two opposed parties—trickster and target—with the goal of incorporating the target into play without his or her knowledge, permission, or both. (12)
I can also recommend the book in general!
Do people here think it’s acceptable to make a practical joke in an academic paper?
i fed “practical joke” to the conceptual analysis machine (a program i generated using claude code), and this is what it came up with (warning: 46 pages of conceptual analysis): The Concept of Practical Joke: Conceptual Analysis and Conceptual Engineering.
Is this a practical joke, David? You have 46 pages but no references or footnotes!
good point! i’ve fixed the program and can do you one better: an article on “the concept of bibliography”, now with a bibliography (i can’t promise no hallucinations though). also now in a more humane 10-page short version. http://consc.net/papers/bibliography_short.pdf
Can you share the code for the conceptual analysis machine?
feel free to email me.
I think this is some joker (not the real David Chalmers) using AI to produce philosophically-sounding but ultimately meaningless slop. All appropriate for the occasion, I would say 🙂
Not sure if you’re going to refine this tool further, but if so, it’s interesting that the abstract doesn’t totally track the document, particularly in the conceptual engineering section. I was looking forward to a discussion of ASYMMETRIC PLAY and that didn’t pay off as expected. (Not only are the proposed concepts given different names, but they seem to carve up the conceptual space differently.) The article as a whole was thought-provoking, though.
good catch! still a few bugs in the system.