I would strongly advise before reading this that you read the novel Fight Club by Chuck Palahniuk, or at least watch the film version, for this writeup discusses the work in detail. Also, exposure to the comic strip Calvin and Hobbes is strongly recommended. This thesis has been well-discussed in many circles and is widely available; the text that follows comes from a paper of my own from 1997; you will likely find other similar theses floating about.

The general thesis here is that Fight Club is merely an adult retelling of the world of Calvin and Hobbes in terms of characters, concepts, and overall theme. Let's break this down piece by piece.

Jack and Calvin are in essence the same character.

You are not a beautiful, unique snowflake...
This is your life, and it's ending one minute at a time.

-- Chuck Palahniuk, Fight Club

At first glance, the primary protagonists of these two works seem to be quite far apart. Calvin seems to be full of youthful optimism, whereas Jack is an adult drowning in self-pity. However, it is easy to see that Jack is quite potentially the man that Calvin grows up to be.

First of all, both Jack and Calvin are very distant from their parents. In the comic strip, Calvin's parents are nameless, merely providing an occasional intrusion into the world he shares with Hobbes, whereas in Fight Club, Jack and his father are admittedly estranged. This lack of bond between Calvin and his parents (after twenty years, their names are never known to us) is thus expressed as the distance described as an adult.

Another strong similarity is that both seemingly are incapable of expressing any degree of interest or fondness towards girls, which will be addressed in more detail shortly. In Calvin's case, he seems to be dominated by females that are focused and persuasive, from the grade-obsessed Susie to his mother and babysitter. This domination by females and subsequent fear of them could reasonably lead to the rejection of intimacy that Jack finds in his adult life.

Jack seems to be the man that Calvin may become once the reality of the adult world sets into his bright youth. Without a true family structure to support Calvin and with only an imaginary tiger to support his fragile psyche, what will adolescence do to Calvin? Jack is clearly one strong possibility.

One final trait of similarity, though, and one that is of major importance for the remainder of this argument, is that both Calvin and Jack have a penchant for imaginary friends.

Tyler is to Jack as Hobbes is to Calvin.

About my boss, Tyler tells me, if I'm really angry, I should go to the post office and fill out a change-of-address card and have all his mail forwarded to Rugby, North Dakota.-- Chuck Palahniuk, Fight Club

Jack and Calvin, both trapped in opressive worlds, dream up an imaginary friend, one that is everything that they wish to be. Interestingly, they dream of two very similar characters.

Both Tyler and Hobbes have an outgoing personality, as compared to the introverted nature of their creators as described above. Both Tyler and Hobbes continually do things that Jack and Calvin would be afraid to do. Tyler and Hobbes are both cool, calm, and collected, and are both dominant over the minds that brought them into existence.

Basically, in both cases, the imaginary creation is a projection of the aspects of life that the imagineer wishes to have, and these traits happen to be very similar.

A final important similarity between Tyler and Hobbes is in the way they react to the primary female in the life of their creator, fulfilling something that is lacking in the life of Jack and Calvin. In both cases, the imaginary friend relates quite well with the primary female, whereas Jack and Calvin seem to be afraid of Marla and Susie.

Marla Singer fulfills a similar role to Susie Derkins.

The last thing I want is Marla moving in, one piece of crap at a time.
-- Chuck Palahniuk, Fight Club

This may seem like the biggest stretch, but it is not. In both cases, the primary female is an independent and intelligent woman with some social problems who finds herself in a combative stance with the protagonist. Yet, the protagonist finds himself attracted in some way to this female.

In both cases, the protagonist finds that his imaginary partner is quite at ease with this female intruder. In Hobbes' case, he refers to Susie as a "cutie" and even dresses up for her, whereas Tyler has a great deal of sex with Marla. In distinct ways, the imaginary friend is acting out the secret desires of the imaginer.

Why is this? In both cases, the protagonist sees something in the female that he believes that he should not like. In Jack's case, it happens to be that Marla is much like a female version of himself; in Calvin's case, he sees Susie as a smart and well-liked girl, and he has neither trait. However, through this basic level of dislike, an attraction grows and blooms, expressing itself through the imaginary friend.

The imaginary friend and imagining relationships through this friend is just one part of the analogy. The idea for the fight club itself is found in Calvin and Hobbes.

Fight Club is an analogy for GROSS

The first rule about Fight Club is you do not talk about Fight Club
The second rule about Fight Club is you DO NOT talk about Fight Club

-- Chuck Palahniuk, Fight Club

In the comic strip, Calvin starts a club named GROSS (for Get Rid Of Slimy girlS), which has a number of frightening similarities with the fight club itself.

In both cases, the clubs are founded by a progenitor and his imaginary friend, and the membership of both clubs is exclusively male. Both clubs hold meetings in secret, mostly to avoid significant numbers of the social world around them. And both clubs result in the two founders fighting each other regularly.

It is clear that in both cases, the clubs are meant to express the repressed social feelings held within both Jack and Calvin. Through these clubs, both Calvin and Jack can feel as though there is a degree of camaraderie in the world with the way that they feel, especially since their closest associate (their imagined acquaintances) founded the club with them.

To Conclude...

If I could wake up in a different place, at a different time, could I wake up as a different person?
-- Chuck Palahniuk, Fight Club

Much as Calvin blasts off from reality to blow things up as Spaceman Spiff, thus does Jack spend the latter portion of Fight Club destroying civilization. The root of both works is this: often a great deal of destruction can come from being unable to deal with introvertedness.

Both works share many of the same themes and share characters with many of the same motivations and concepts. It is in this repeated duality that one can clearly see that concepts of Calvin and Hobbes are spread throughout the later work Fight Club.