system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What makes a dialect a dialect and not a new language?

Sometimes dialect sounds so different that it sounds like a language on its own? How do linguists classify a dialect as dialect?
gpt
Politics mostly.

Basically don't look for any kind of hard, logical rule as to when something is a dialect and when it is a language. Because you won't find any hard rules without a ton of exceptions.

Languages aren't neat and discrete and human attempts to categorise them are messy and flawed.

That's how you get Serbian, Croatian and Montenegrin being considered "languages" while being essentially identical while Arabic is considered a "language" despite its many "dialects" being unintelligible to each other.

"A language is a dialect with an army and a navy" is a well-known quote.