Friends first aired in 1994, and by its last episode in 2004, Joey had gotten a lot dumber. The show ran for 10 seasons, making it one of the most successful and well-loved American sitcoms of all time. Over the course of its 10 years, the main group of characters — Chandler, Ross, Monica, Phoebe, Rachel, and Joey — grew as the series progressed. Each of the Friends gang's change from season 1 to season 10 is palpable, but it's Joey's devolving intelligence that stands out the most.
In the pilot episode of Friends, Joey Tribbiani (Matt LeBlanc) is immediately characterized as a stereotypical womanizer and slightly naive. This is expanded upon in a later season when the Friends recount how they first met each other. Upon first meeting Monica, Joey took her offer to have lemonade in her apartment as some sort of sexual advancement, misreading the situation completely. He starts the show off by being fairly simple-minded but becomes increasingly feebleminded with a childlike understanding of even the most basic concepts. Examples such as the reference to his ''Joey's apple'' and the infamous scene of Phoebe trying to teach him French show just how much dumber he got.
Related: Friends: How Did Joey Pay For The Boat (Is It A Plot Hole?)
The reason for this devolution of his intelligence is likely because initially writers were finding their footing with each character and playing it relatively safe for the Friends pilot and the rest of the first season. Once they had the reaction of the audience to play off of, they seem to have played up the parts of the characters that people liked the most and which parts drew the most laughter, leading to most of the Friends group becoming parodies of their original selves. Ross goes
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