I recently left the Museum of Natural History, Halifax, Nova Scotia, and was screamed at by a toddler. ''Rrrrraaaaaagh!'' he yelled, his eyes wide, teeth bared. I screamed back. It's the universal language of the Hulk, the grumpy green superhero, who was printed on my T-shirt.
Philosophers are historically associated with togas, tweed jackets and black turtlenecks. This is obviously a dim stereotype, but folks remain surprised by my comic clothing. As if the categories of ''public intellectual'' and ''pop culture'' were primal opposites, doomed to cancel each other out with a flash of knowing irony.
I am not being ironic when I say that superheroes, particularly in the medium of comic books, are valuable to me. Given the ubiquity and success of superhero films recently - Avengers, Batman and Spider-Man, to name the most lucrative and critically lauded - it is worth revealing why.
This is not a defence of comics or graphic novels, though I'd happily pen one. Superheroes are not the only characters of the comic book medium. They are only one genre among many, including romance, slapstick, domestic drama. This is, instead, an argument for the worth of mass-market superhero literature at its best, of the kind exemplified by Captain America, written by Ed Brubaker and drawn by Steve Epting.
The medium is important to the genre. There is nothing quite like a well-drawn, coloured and written comic page. The illustration, for example, is more than a decoration. It is part of the story's visual language. As with film, the art suggests threat and vulnerability, or conquest and power; it gives the impression of oppressive heat or lonely chill, romance or aggression, and the connotations of size, gesture, physiognomy, and so on.
One issue of Batman, ''Death in the Family'', features the murder of the crime fighter's partner, Robin. There is nothing dignified in his death: beaten by the frenzied Joker with a crowbar. It is messy, painful and pointless. One illustration, by Jim Aparo, shows Batman cradling his sidekick's corpse. Batman's hulking muscular physique is hunched over, on his knees; his partner is limp, his characteristic acrobatic energy gone. The writer, Jim Starlin, does not need to stress Batman's grief or powerlessness, or Robin's foolhardy youth - the artwork does it in a single frame. In another frame, a single word, ''gone'', sums up the tragedy.
These images, unlike film, can also be slowly savoured: they invite a more patient contemplation, in which the illustrations, text and layout can be delineated and comprehended, without missing the action. This visual language combines with the text in interesting ways: Thor's faux-archaic speech, Iron Man's loquacious mickey-taking, Rorschach's malcontent monologues, all written with their own font and layout. Comic books do not simply write characters; they make personality part of the art and format.
This is important, because character is at the heart of the superhero comic. Superpowers or special suits are dull without the psychological or existential struggles they symbolise. And superheroes usually face off against supervillains, anyway; their physical superiority is regularly neutralised. The mutant Wolverine, for example, is a martial-arts master, blessed with superhuman strength, speed, senses and healing; he even survived decapitation. But what makes him heroic are his recognisably human struggles, not his metal claws: channelling his instincts; co-operating with others; acting out of reflection not reflex, morality not guilt or rage.
Comic book stories express these struggles by portraying them on a bigger scale. Like Plato's utopian republic, the author's ''good soul'' writ large, the superhero's special powers are life magnified. Potent muscles, technology or mind - they can be escapist fictions, but they can also be symbolic versions of our own fantasies and anxieties. Ghost Rider, for example, is a spirit of vengeance: the flaming skull equivalent of our own righteous rage and wounded victimhood. What begins as supernatural revenge also looks like mad vigilantism, in which the hero's own life is twisted: ordinary domestic love, the very thing one hopes to protect from violence, is lost.
Likewise for Superman, who comes close to god-like invincibility at times: what keeps him from tyranny is his moral code, and characteristic self-awareness and self-control. The question remains for the readers: can our sympathy, restraint and foresight keep up with our physical, technological or political power?
This only a tiny sample, from popular mainstream comics; there are more examples from alternative authors and studios. And I have focused on character, rather than plotting, or broader political and economic issues, like the presidency of George W. Bush explored in the Ultimates.
The point is that comic superheroes exemplify common human struggles in unique illustrative medium. This provides readers with iconic characters: memorable archetypes that speak to specific times and places, while transcending both. Hence their ongoing appeal: there are many stories, and many alter egos behind the mask or muscles, but Batman, Captain America and Black Widow endure.
In 100 years, this laptop may be in the Halifax museum. The angry character on my T-shirt, in one form or another, will be screaming as he always has.
Dr Damon Young is a philosopher and the author of Distraction: A Philosopher's Guide to Being Free.