Why Do We Laugh? Part Two

We have explored the major theories of humour that have emerged through history:

  • Superiority: recognising the misfortunes of others
  • Relief: release of psychological tension
  • Play: laughter as mental play
  • Incongruity: violation of our mental patterns or expectations

More recently Benign Violation has come along to unite elements of play and incongruity.

There are various competing theories because each of them fails to capture everything funny. Yes, jokes release psychological tension, but so does a bath. Yes, we laugh at the misfortune of others (a fat lady falling into a pool) but often we find their misfortune upsetting instead.

Meanwhile the opposite of misfortune can be hilarious, such as team’s worst player doing something unexpectedly miraculous. That would be an example of incongruity, as is this joke:

A little boy who had never spoken a word said one night, “This steak is terrible.”
His parents were amazed. “Why have you never said anything before?!”
“Until now,” he replied, “everything has been satisfactory.”

The boy’s comment could also be classed as a benign violation, but with two explanations possible, that means that both are too vague to capture exactly what makes this joke funny. What kind of violation? What is incongruous? The terms are so diffuse that they bring us barely any closer to the central question: what is funny?

A complete theory of humour: an impossible task?

A complete theory of humour needs to capture everything funny while excluding everything that is not. This is such a difficult task that it has literally never been done.

Incongruity and benign violation seem to come the closest, but it is easy to point out exceptions. Jaywalking is a benign violation, but it isn’t funny. An arrested policeman is incongruous, but that isn’t funny either. Slightly better is a traffic policeman arrested for jaywalking. Better still is a traffic policeman arrested for jaywalking as he is crossing the road to arrest someone else.

Here we have a hint at the answer: the violation or incongruity must connect in a very particular way.

The Benign Violation theory is almost there and might just make the grade with a slight expansion and a little tweak. To step into the fray, let’s examine the joke rated in a study as the “world’s funniest”.

Two hunters are out in the woods when one of them collapses. He doesn’t seem to be breathing and his eyes are glazed. The other guy whips out his phone and calls the emergency services. He gasps, “I think my friend is dead! What can I do?” The operator says, “Calm down. I can help. First, let’s make sure he’s dead.” There is a silence; then a gunshot is heard. Back on the phone, the guy says, “OK, now what?”

Just like almost any joke, people can find it funny but cannot explain why they find it funny. Various responses come back such as, “He’s so stupid”, or “He killed him”, but this doesn’t help as neither death nor stupidity are universal prompts to laughter.

There is an element of the superiority theory, but certainly not enough to explain it. Incongruity is better, since we can certainly see the collision of two frames of reference: first, the hunter trying to help his friend, and the second, killing him, also by trying to help.

The second frame is precisely the opposite of the first but with a link between them (i.e. trying to help). The two frames are incongruous, but certainly fail to capture what’s funny – otherwise the joke could be a doctor killing a patient by trying to help. We get closer by seeing that the hunter tries to help his friend by following specific instructions, but kills him, exactly by following instructions. He wants to help his friend immediately, so he acts immediately, and again that’s what kills him.

We can see that just having two different frames of reference united in the punchline is not enough to make the joke funny. In this joke at least, the frames of reference have to be in mirror image. And what’s more, the mirror images have to be linked together by something that captures both. This is the “Now, what?”, the punchline.

Appreciating the first frame, the second frame, and the link between them creates a new perspective, and that fresh view seems to be what makes us laugh. So it’s not just two frames of reference colliding, but a very specific collision that produces a new unity. But what exactly is this unity that can make a good punchline?

Some have suggested the unexpected, but this cannot be it because often something entirely expected is hilarious, such as watching Life of Brian for the tenth time or watching someone repeatedly make the same mistake, just as you are waiting for it. The anticipation is even part of the fun.

Others have suggested that a punchline must be about something going wrong, but that’s not quite all of it either. A paper plane thrown in a football stadium had 80,000 people in laughter when it hit a player in the back of the head, and to do so the throw had to be not just right, but perfect:

What’s funny can be about something going wrong (it was certainly wrong for the player) but wrong in precisely the right way.

Biologists face a similar conundrum when seeking to understand the genetic mutations that drive the evolution of life. Mutations are produced when cellular replication goes wrong and are almost always harmful, but occasionally a mutation produces a new adaptation. The helpful mutation cannot be totally alien from the existing structure but must fit within it, and so like a joke, it too is wrong in precisely the right way – or as the best of jokes are often described, “so wrong, but so right”.

To explore how mutations take the forms they do, biologists have turned to various mathematical models that apply to complex, dynamic systems – such as chaos theory. The ordered state is the existing genetic code, the chaotic state is the jumble of all possible genetic combinations, most of which will be useless. The helpful mutation forms on the creative border between order and chaos. Too much chaos produces nonsense, too much order produces no change. The evolutionary leap is the perfect blend of the two. Could a similar perspective be needed for jokes?

Looking closer, it’s true that the elements of unexpectedness, incongruity and going wrong are indeed part of a broader category that could be described, both psychologically and mathematically, as chaos.

In a joke, the first frame of reference is order: the known, established way of things – what should happen. The second frame of reference is chaos: the unknown, the random, the unexpected. The punchline brings the frames of reference together, and the blending is a new perspective which makes us laugh.

For a joke to work, like a mutation, it can’t be just any random collision of order and chaos but a precise fusion, one foot in each. Let’s look deeper to see what this link could be.

Someone diving into a pool isn’t funny. Someone pushing someone into a pool can be a little funny, but not really. Someone falling into a pool is funny. Someone falling into a pool because she’s trying to look cool is even funnier. Even better if she’s trying to capture the moment with a selfie and takes her phone in with her. Here what went wrong is not only the opposite of her intention but occurred because of it.

Two frames of reference are colliding: a) trying to look cool and b) falling in the pool. The fusion making it funny is that A causes B while B negates A. The elements intertwine and a new whole emerges. Now we can attempt to put what’s funny into a formula:

AB is funny where A → B and B → A

You might notice that the whole structure of the joke is a self-reflexive loop: the end recalls the beginning and the beginning foreshadows the end. The whole package of the joke only works with all elements neatly linked together – which explains why jokes are so easy to ruin by telling them incompletely or in the wrong order. The idea of the self-reflexive loop is an extremely important concept in a variety of fields and has been used to explain phenomena as diverse as quantum paradoxes, the origin of life, and consciousness, so it is no surprise that humour adopts the same form.

Stand-up comedians intuitively understand the looping pattern of comedy and often it create it consciously: a common technique is the “call back”, where a previous joke becomes the basis for a later one. A real artisan lets these jokes continue to build and loop back, and the set gets funnier and funnier as it connects additional and deeper loops.

The best jokes don’t rely on one loop but several. Different people can “get” the same joke, but some will find it funnier: more loops have connected in their minds, or more deeply. But let’s see if this pattern holds with other jokes.

Just like the lady looking uncool by the very act of trying to look cool, here we have someone defacing a stop sign by telling everyone not to deface stop signs. In both examples we have two colliding frames of reference, and the link is that the first went wrong in the very specific way it tried to go right. The stop sign is of course deliberate, and the lady falling in is not, but neither matters – the humour simply lies in the perspectives colliding in such a way that they link.

The lady falling the pool wouldn’t have been funny if she deliberately fell in, or if she wasn’t a show-off. The defaced stop sign wouldn’t have been funny with almost any other message (e.g. “stop walking your dog”) – no link, therefore no laughter. It may have been even funnier if the stencilling was perfect, giving the illusion of a well-meaning bureaucrat making an ironic blunder rather than a serial prankster. For a joke to hit, the second frame of reference must fit the first like a key in a lock. The punchline is the common element which has one meaning in the first (ordered) frame of reference, and the opposite in the second (the chaotic). We can visualise this unity with the following ancient symbol:

That’s too ordered to be funny. But throw in the right dash of chaos and it is:

Let’s summarise what we have so far. Something funny is:

  1. A collision between two frames of reference, order and chaos.
  2. The order shapes the chaos and the chaos negates the original order.

You could visualise this as a lock (order) moulding the locksmith’s putty (chaos) which then unlocks the lock (new order). Too much chaos and the lock is not opened but broken. Too much order and the lock doesn’t budge at all. A joke must hit the sweet spot. Let’s return to what is admittedly a very difficult joke to explain, the mute boy and the steak.

Order: The little boy never speaks. (Implication: he never speaks because he is mentally deficient)
Chaos: The little boy speaks.
Chaos shaped by order: The little boy complains about the dinner.
Original order unlocked: The little boy’s silence has been voluntary. We now see he is the opposite of mentally deficient: discerning, worldly, even arrogant.

Like any good joke, the loop above is not the only one involved. Others may be expecting parents to be in control, but finding them confounded; that first words are usually joyful, but here they are baffling; or that children are usually erratic but easy-to-read, but this child is wise and inscrutable. Each is another mirror-image chaos / order connection. These additional links make it funnier, assuming you have the initial assumptions in mind to form them.

Now we can attempt an explanation of not just what makes something funny, but why one joke is funnier than another. Even though the stop-sign joke fits the structure perfectly, it is not quite as funny as the steak joke.

The stop-sign joke works on a single loop, but the steak joke has several and these are much deeper, reaching into our whole understanding of parents and children. When two people hear the same joke, one may find it funnier because their mind has formed more connections; alternatively, they form the same connections at a deeper level.

It is the strength and depth of the mental loops that makes one joke funnier than another. While jokes that fuse more chaos with more order are funnier, they are also harder to find and fail more easily: a joke relies on all the elements fitting together neatly. Meanwhile a man running into a post will always be funny.

But this is not quite the full story. We have sought to explain the precise nature of the “violation” or “incongruity” that makes something funny, but we must also address why these order / chaos collisions sometimes fall flat – in other words, what makes the violation sufficiently “benign” for laughter.

Psychologists understand that our perception of everything in the world relies on two types of processing: top-down and bottom-up. What we see is a product of the information carried in by our optic nerves and the built-in algorithms our brain uses to process it. When it comes to jokes, we might register a mental loop but still find it unfunny if we see it as hurtful. That is top-down inhibition neutralising the raw data coming in. An example:

Q: Why did Hitler commit suicide?
A: He got the gas bill.

While this joke is funny in some situations, it would not be if you told it at a Holocaust Museum.

Of course some people have no shame and enjoy telling jokes that deliberately violate the setting. They find these jokes even funnier because there is an additional mental loop in play, e.g. the fact of telling a Holocaust joke at a Holocaust Museum.

The inhibition of humour occurs largely in the prefrontal cortex. This “executive centre” of the brain reaches conclusions more slowly than lower levels of because it integrates information from a much wider area. What we find funny also seems to be registered in the prefrontal cortex, but in a specific area of it, namely, the medial ventral prefrontal cortex.

The difference might explain why an audience may initially laugh at a joke but a moment later think better of it and groan. Here it has taken the slower work of inhibition a few seconds to catch up. The more abstract the inhibition, the slower and weaker its effect. Hence someone will stop finding a racist joke funny much faster if someone of that race is sitting next to them.

There are also situations where we laugh despite our best efforts – the top-down inhibition kicks in, but it is too little, too late. The fat lady falls into the pool, we laugh, then as she struggles out looking upset, inhibition acts to shut the humour down.

But sometimes this sets off a runaway effect where the very act of trying not to laugh becomes funny. Here a new connection has formed: laughter is inappropriate (order) and we can’t help laughing (chaos). The more ordered the setting (e.g. important meeting, news readers, polite company), the more potent this bonus connection becomes.

Of course, some settings are simply too deeply inhibited for any normal person to find funny, such as the funeral of a loved one. Yes, it would fit the order/chaos structure for the coffin trolley to roll towards the church steps, the coffin bouncing down, the corpse cartwheeling out before the shocked mourners … but not funny. Unless all inhibition was lost by having the scene as a cartoon, or the onlooker as a psychopath. That’s where the difference in what constitutes “benign” varies between individuals and with their emotional distance from the event.

We can see the effect of top-down inhibition when we introduce it into the previous jokes. Imagine if the little boy’s mother starts sobbing and asks why he did this to them, never speaking all these years. Not funny. Or if the lady trying to look cool doesn’t fall into a pool but in front of a train. Not funny either.

With these examples, we can see that a joke might become unfunny not just because the humour is neutralised by inhibition, but because the alteration wrecks the previous neat fit of order and chaos. A joke is a controlled injection of chaos – it must mirror the existing order. With a train not a pool, the dose of chaos is too much, as the opposite of looking cool is embarrassment, not death.

Now another possibility arises – what if a situation fits the order / chaos structure perfectly but in an inherently dark way? Imagine the lady is not trying to show off but to prevent her rolling pram from reaching the train tracks. The pram stops and she tumbles in and dies. Even worse if her efforts nudge the pram in too.

While this scenario has the identical structure to the show-off falling in the pool, it has become not comic, but tragic. Another example with the same structure is the phenomenon of the human stampede.

In 2015, over 2000 pilgrims died in Mecca during the Hajj. A crowd fearing for their lives caused their own deaths by their very efforts to survive. What was supposed to be their peak life experience became their worst. Devotion to God became punishment from God. Here the chaos perfectly matches the order just like the joke, which brings the question – was Kierkegaard right to claim that comedy and tragedy are as closely linked as mirror images?

To explore this we will look at the quintessential tragedy, Oedipus Rex by Sophocles. When Oedipus receives a prophecy that he will one day kill his father and marry his mother, he flees to stop it happening, but by doing so, unwittingly does exactly as Fate decreed. Here the first frame of reference is preventing the prophecy and the second frame of reference is the opposite, the prophecy fulfilled. The link? The attempt to prevent the prophecy. If order is what should happen, and chaos is what should not, then tragedy occurs when what should not happen happens precisely because of efforts to prevent it. Like comedy, tragedy also fits like a key in a lock.

The audience has the view of the gods and can watch it all unfold, both amused and appalled. This is the heart of irony, where things go wrong so perfectly that it seems planned by a malign Fate. Irony can be both comic or tragic, depending on our feelings towards the target and the extent of the fallout. A lady trying to look cool but falling in a pool may be funny to most, but tragically sad to someone who knows her deep insecurity and need to be loved. The shared structure of comedy and tragedy is another reason why some moments cause laughter followed by shaking heads and groans. Often the situation can go either way and we feel both at the same time.

This might bring us back to the evolutionary advantage of humour, both for groups and individuals. We saw how humour might have developed as groups harnessed a naturally pleasurable reaction to smooth over potential conflicts. Deliberate low-level violations introduced small doses of chaos that inoculated the group against the violence that might come from larger violations.

Similarly, humour delivers small, manageable doses of the tragic to blunt its full force when real tragedy inevitably arrives. If this is true, then comedy is like Mithridates VI of Pontus regularly taking small doses of poison to protect himself against the large dose that must be coming for him some day. His program worked marvellously well until the day his enemies were closing in and he tried to poison himself. It didn’t work.

That story is either tragic or quite funny, depending on your feelings towards Mithridates VI. Either way it is ironic: something going wrong in precisely the way it should have gone right; frames of reference fitting together like lock and key.

We are particularly captivated by stories that fit this ironic structure, such as Forrest Gump, whose very simplicity propels him into ever more fame, or Fargo, where the very efforts to get out of trouble make the trouble much worse.

The events from history we most remember are not necessarily the most influential but the most ironic, even when totally wrong, such as Napoleon being short or Hitler being Jewish. It is the same with rumours that quickly spread, like the story that the man who wrote the upbeat tune Don’t Worry Be Happy killed himself. It was completely untrue, but the irony was irresistible.

Comedy and tragedy are fascinating because both exist at the border of order and chaos which we are neurologically primed to find interesting. We happily read tragic stories or watch comedies alone purely for the intellectual appreciation, but they are felt more deeply when shared which reflects the deep social ties behind their evolution.

Evolutionary psychologists point to humour’s knack for binding people together. But almost any shared reflex could do the same, so why it would be based on the sudden intrusion of chaos, a violation, a moment when things go wrong? That element of humour seems entirely counterproductive to the evolutionary spirit, with Exhibit A being all the lethal things teenage boys do “for a laugh”. But looking deeper gives us a hint why this collusion of chaos and pleasure might be something more than an accident.

Imagine a proto-human hoping to cure his hunger and eating some colourful mushrooms, which then kill him. Given that it was precisely the desire to stay alive that poisoned him, his unfortunate demise fits the structure of both comedy and tragedy. Seeing him laid out on the turf would have been either sad or hilarious depending on the troupe’s feelings towards him, but either way the event was profoundly interesting.

That’s exactly how the event should be experienced, because the lesson of the mushrooms is crucial to know. Something that looks like live-giving food but bringing death is ironic. The shared laughter or weeping that followed would bind the troupe together while the juicy story would rapidly spread to become part of their shared mental atmosphere, and both the knowledge and the unity would aid the troupe’s survival.

Other moments that fit the pattern would have the same effect and spread in a similar way. Beneath those individual moments are the neural circuits that make the border of order and chaos interesting. Having a burst of interest when our minds register this point makes it more likely that we would seek it out – a very helpful tendency to have, because this is where the magic of creativity happens.

And so after millions of years evolving in a chaotic world, we now naturally enjoy a dash of chaos and seek it out. But as with anything, too much can be trouble. Despite their wealth and fame, comedians suffer rates of anxiety, depression and drug abuse far outstripping the general populace. Too much chaos – even in a world view – can be destabilising. The tragic clown is a common theme from King Lear to Seinfeld to The Joker, and this time not just because it is ironic, but because it is true, which is why it is ironic … another example of how these loops multiply.

We find something interesting when we see something familiar in a new way, making connections we previously could not see, especially if there is a reversal of expectations. This is precisely the kind of information that our ancestors most needed. The spiny shell hiding delicious food or the floating log that could surge from the water with snapping jaws, these are highly valuable paradoxes for the primate brain to resolve, and remember.

One of man’s most helpful adaptations was seeing the order within chaos and the chaos within order. Bored with too much order but panicked by too much chaos, we found the happy medium most interesting and learned to seek it out.

Movies, books, sport and parties give us a controlled dose of the unknown where we can participate in the story, the game, or the lives of other people but don’t have to take on the perils of the full reality. Sport is war without weapons. Jokes are tragedy made safe. All our entertainments are partly safe and familiar, partly chaotic and dangerous – at least in imagination. We like learning new things, and the further and deeper new connections go, the more of a buzz when we see them – but there’s a catch. Any new information risks upsetting the assumptions we use to navigate the world. When we are “upset”, we are that literally: chaos can be unsettling and destabilising to the point where we choose to ignore it, dismiss it, or even shoot the messenger.

The most successful recent books for children are the Harry Potter series, which let children view their reality in a new way. Harry is a kid dealing with the travails of childhood – difficulties with parents, going to school, friends and relationships – that’s order, the familiar, the known. Too much of that order is being bored, trapped, lonely and unimportant. The injection of chaos is an exciting and dangerous new world where Harry has friends, status, adventures and meaning. But what could bring those opposites together? A place that is both a school and a magic kingdom as Harry is both a boy and a wizard. The new paradigm is a blend of the old order and its opposite. Throw in close alignment with archetype of the hero and you have a bestseller.

Just like humour, what we find most interesting is a collision with a new frame of reference where the new is a mirror image of the old.

For example, let’s take the success of The God Delusion. The established paradigm: God exists. The opposite: God does not exist. The new paradigm: God is a delusion.

This new paradigm says yes, God exists, but not as you thought – God is an image in your mind that has been fooling us. The new paradigm unites both the old order and forges a new concept, and we have another catchy bestseller.

Hegel believed it was this very structure that was the way ideas moved forward in philosophy: the clash between an idea (thesis) with its opposite (antithesis) leads to a new idea (synthesis), which is now a new thesis, which meets its opposite, and on it goes.

Kuhn described a similar pattern in science: new data clashing with old ideas to cause a paradigm shift.

Marx believed history unfolded in the same way. Even the stock market shows the pattern with bouts of buying and selling coalescing into candles, breakouts, falls and bull-runs and eventually a new normal. In the eternal clash between order and chaos, new complexity is always forming.

If this theory is true, then it illuminates the jokes we most enjoy and what we find interesting at different stages of the life cycle. With age, intelligence moves from fluid to crystallised and knowledge increases. With their limited life experience, children find humour in very simple connections that need little knowledge to grasp.

For example, a parent dropping a glass of milk, or a bird flying around the house. Each is the simple opposite of the established order. Even infants understand a very basic joke: the peekaboo game. When infants see a face disappear, it is as if it has ceased to exist. To see it reappear again is the precise opposite of the established order, and hence funny. In later adulthood, knowledge is high, but intelligence has become crystallised, which means the brain can make fewer non-linear connections.

That means the jokes older adults enjoy are often puns and word-play, a phenomenon so intuitively understood that we have a category called “Dad Jokes”. The change in jokes is reflected in the types of stories each age group tends to tell. Children tell stories with simple elements but often bizarre connections, reflecting fluid thinking but little knowledge, while the elderly tell stories that are more detailed but highly linear.

These natural changes in knowledge and intelligence reflect when different types of artists reach their peak. The sweet spot for creativity is when knowledge (order) and fluid intelligence (chaos) intersect most strongly, and this varies between fields. Since it is quicker to listen to a song than read a book, musical knowledge is gained more quickly than literary knowledge and accordingly, the peak for musicians comes younger, especially pop musicians – who have less knowledge to master.

The human mind appears well tuned to appreciate the border between order and chaos and seek it out, and all so deeply that the process remains unconscious. We find things funny, interesting or tragic immediately, without needing to think about it, and long before we can understand why. The mind itself is attuned to this most elemental structure of reality because this is the environment in which it evolved. Most importantly, it is not just any old chaos that creates a new level of order. The chaos must fit in a particular way to form new complexity.

The pattern reflects not just how knowledge is won from a chaotic world but how life itself evolved: where something goes wrong (in replication) that turns out to be right (in adaptation). And so jokes are not just something that separates humans from animals, but a glimpse of the processes which turned animals into humans in the first place: order moulding chaos to produce a new form that unites both, something that goes wrong, but wrong in just the right way. All this means that the fat lady falling into the pool mirrors the deepest layer of reality, and when you laugh, you grasp it too – without even realising. Which is, of course, quite ironic.

Further reading

Morreall, John, “Philosophy of Humor”, The Stanford Encyclopedia of Philosophy (Fall 2020 Edition), Edward N. Zalta (ed.),
Aldis, O., 1975, Play Fighting, New York: Academic Press.
Andrew, R. J., 1963, “The Origins and the Evolution of the Calls and Facial Expressions of the Primates,” Behaviour, 20: 100–109.
Aquinas, Thomas, Summa Theologiae, trans. Thomas Gilby, London: Blackfriars, 1972.
Aristotle, The Basic Works of Aristotle, ed. R. McKeon, New York: Random House, 1941.
Beattie, J., 1779, “Essay on Laughter and Ludicrous Composition,” in Essays, 3rd ed., London.
Bergson, H., 1900 [1911], Laughter: An Essay on the Meaning of the Comic, C. Brereton and F. Rothwell (trs.), London: Macmillan. [available online]
Boyd, B., 2004, “Laughter and Literature: A Play Theory of Humor,” Philosophy and Literature, 28: 1–23.
Bressler, E. R. and S. Balshine, 2006, “The Influence of Humor on Desirability,” Evolution and Human Behavior, 27: 29–39.
Humour: A Very Short Introduction, Oxford: Oxford University Press.
Cathcart, T. and D. Klein, 2008, Plato and a Platypus Walk into a Bar … : Understanding Philosophy Through Jokes, New York: Penguin.
Chafe, W., 2007, The Importance of Not Being Earnest: The Feeling behind Laughter and Humor, Amsterdam: John Benjamins.
Cicero, Quintus Tullius, 1942, On the Orator, Book II, E. W. Sutton and H. Rackham (trans.), Loeb Classical Library, Cambridge MA: Harvard University Press.
Clark, M., 1987, “Humor and Incongruity,” in The Philosophy of Laughter and Humor, John Morreall (ed.), Albany: State University of New York Press, pp. 139–55.
Clewis, R., 2020, Kant’s Humorous Writings, New York: Bloomsbury Academic.
Dewey, J., 1894, “The Theory of Emotion,” Psychological Review, 1: 553–569.
Eysenck, H., 1972, Foreword to The Psychology of Humor, J. Goldstein & P. McGhee (eds.), New York: Academic Press.
Freud, S., 1905 [1974], Jokes and Their Relation to the Unconscious (Der Witz und seine Beziehung zum Unbewußten), James Strachey (tr.), New York: Penguin.
Greengross, G., 2008, “Survival of the Funniest,” Evolutionary Psychology, 6: 90–95.
Hobbes, T., 1651 [1982], Leviathan, New York: Penguin.
Hurley, M., D. Dennett, and R. Adams, 2011, Inside Jokes: Using Humor to Reverse-Engineer the Mind, Cambridge, MA: MIT Press.
Kant, I., 1790 [1911], Critique of Judgment, James Creed Meredith (tr.), Oxford: Clarendon Press.
Kierkegaard, S., 1846 [1941], Concluding Unscientific Postscript, D. Swenson and W. Lowrie (tr.), Princeton: Princeton University Press, 1941.
Journals and Papers, Vol. 2, H. Hong and E. Hong (eds. and trs.), Bloomington: Indiana University Press, 1970.
Li, N. P., V. Griskevicius, K. M. Durante, P. K. Jonason, D. J. Pasisz, and K. Aumer, 2009, “An Evolutionary Perspective on Humor: Sexual Selection or Interest Indication,” Personality and Social Psychology Bulletin, 35: 923–936.
Lintott, S., 2016, “Superiority in Humor Theory,” Journal of Aesthetics and Art Criticism, 74: 347–358.
Martin, M. W., 1987, “Humor and the Aesthetic Enjoyment of Incongruities,” in The Philosophy of Laughter and Humor, John Morreall (ed.), Albany: State University of New York Press, pp. 172–186.
Panksepp, J., 1993, “Rough and Tumble Play: A Fundamental Brain Process,” in Parent-Child Play, Kevin MacDonald (ed.), Albany: State University of New York Press, pp. 147–184.
Philips, M., 1984, “Racist Acts and Racist Humor,” Canadian Journal of Philosophy, 14: 75–96.
Plato, The Collected Dialogues of Plato, E. Hamilton and H. Cairns (trs.), Princeton: Princeton University Press, 1978.
Polimeni, J. and P. J. Reiss, 2006, “The First Joke: Exploring the Evolutionary Origins of Humor,” Evolutionary Psychology, 4: 347–366.
Provine, R., 2000, Laughter: A Scientific Investigation, Harmondworth: Penguin.
Raskin, V., 1984, Semantic Mechanisms of Humor, Dordrecht: Reidel.
Schopenhauer, A., 1818/1844 [1907], The World as Will and Idea (Die Welt als Wille und Vorstellung), tr. R. B. Haldane and J. Kemp, 6th ed., London: Routledge & Kegan Paul.
Schultz, T., 1976, “A Cognitive—Developmental Analysis of Humor,” in Humor and Laughter: Theory, Research and Applications, Tony Chapman and Hugh Foot (eds.), New York: Wiley, pp. 12–13.
Shaftesbury, Lord, 1709, “Sensus Communis: An Essay on the Freedom of Wit and Humour,” republished in 1711, Characteristicks of Men, Manners, Opinions, Times, 1st ed., London (4th edition in 1727).
Spinka, M. et al., 2001, “Mammalian Play: Training for the Unexpected”.
Tisljar, R., and T. Bereczkei, 2005, “An Evolutionary Interpretation of Humor and Laughter,” Journal of Cultural and Evolutionary Psychology, 3: 301–309.
Van Hooff, J. 1972, “A Comparative Approach to the Phylogeny of Laughter and Smiling,” in Non-Verbal Communication, Robert A. Hinde (ed.), London: Cambridge University Press, pp. 209–241.