If you’ve seen any episode of “It’s Always Sunny in Philadelphia,” you probably picked up on the dynamic of the main gang. Charlie Kelly, played by Charlie Day, is more often than not framed as the idiot of the group, a classic trope in sitcoms. If you haven’t watched “Always Sunny,” think Joey Tribiani from “Friends,” but if the characters in “Friends” screwed each other over constantly. It’s revealed in the second season that Charlie is illiterate and often prone to confusion. He lives a very non-traditional lifestyle (but he’s surprisingly well adjusted), filled with many odd practices including huffing glue, eating cat food and chugging beer in order to sleep (gross, albeit effective). He occasionally plays the straight man, acting as the voice of reason for his equally insane friends; still, it is understood that he barely made it through school and is barely making it through adulthood. He’s also very childlike, immature and unable to properly express himself. However, there exists multiple episodes and details that hint at his hidden intelligence that far outmatches those of his friends.
Charlie embodies many natural abilities that indicate a high level of intelligence. Fans know that he is very naturally creative and gifted at music, the piano specifically. He wrote, directed and acted in a play that he randomly decided to create — with no ulterior motives –– while actively working against his friends who were characteristically trying to use his play for their own means. His perfect pitch was revealed in the episode “Charlie Work” when he improvised an incredibly intricate plan for the gang’s bar to pass a health inspection despite numerous obstacles. In the same episode, he also managed to immediately figure out and execute the gang’s separate “chicken, steak, and airline” scheme with no prior information.
Charlie is very talented at very specific tasks that he enjoys, making him an “idiot savant.” He excels at the janitorial work required to run the bar and anything creative or musical while being inept at any of the skills imparted by a formal education — notably, literacy. His crafty solutions to problems often come off as unintelligent because his baseline understanding of the world is weak, having been failed by his parents and the education system due to his implied learning and developmental disorders — or maybe he’s just a wildcard.
Charlie successfully launched his own company, “Kitten Mittons,” that would have made him millions had he not been outlawyered by blindly signing the company over to the show’s vindictive lawyer character. This probably shouldn’t be legal considering Charlie can’t read. Regardless, he’s only well-versed in bird law, not business law. This is later proven during the trial of the century, where he beat said lawyer in a legal case with an incredibly complex, focused and intelligent argument (until he tried talking to a bird).
However, the best display of his intelligence is of course his invention that allows spydars to talk with cats. In the episode “Flowers for Charlie,” Charlie is given a placebo intelligence pill that would supposedly make him smarter. Once he begins taking the placebo, he experiences many effects, including seemingly becoming a chess master and speaking fluent Mandarin. Obviously it’s revealed that he does not speak Mandarin nor does he know how to play chess; those effects were faked by the researcher. However, the placebo Charlie received confirmed his day-to-day intelligence despite being treated like an idiot by his friends. What this episode proved was that Charlie’s work is much harder than everyone believes, as the rest of the gang are unable to complete the most basic “Charlie work” of catching and bashing rats. If we understand the rest of the gang (minus Mac) as smart, yet they can’t catch a single rat, that proves Charlie is smart in his own way. He isn’t an idiot, he just doesn’t care enough to learn about things that don’t interest him just to appear smarter.
Charlie is also very intelligent when it comes to conserving money. He’s able to feed himself for a month on just $5, sews his clothes so as to refrain from buying new ones and wears jeans he finds under bridges after boiling them (to clean them). He also conserves money for the bar by burning trash for fuel — albeit with questionable atmospheric consequences. He burns the bar’s trash in their furnace, keeping the bar warm and totally green as well as getting that nice smokey scent that definitely doesn’t smell like trash. While his solution isn’t the most environmentally friendly, his approach is only limited by a lack of accurate information.
Charlie may lack a formal education, but he’s very naturally gifted and intelligent when it comes to the things that interest him. When he’s motivated, he becomes a mastermind and executes incredibly complex plans all by himself. He may not be fully literate in English, but it’s later revealed that he is literate in Gaelic, which makes him bilingual. Charlie utilizes his specialized intelligence only when he cares greatly about the outcome, unlike the rest of the gang that ruins well-thought out plans due to their overconfidence and focus on presentation.