What was the main argument of plessy in plessy v furguson?

In Plessy v. Ferguson, Homer Plessy argued that Louisiana's segregation laws violated the Equal Protection Clause of the Fourteenth Amendment. He contended that the "separate but equal" doctrine established by the law was inherently discriminatory and stigmatized African Americans. Plessy maintained that racial segregation enforced by the state was a violation of his civil rights, as it marked him as inferior based solely on race. Ultimately, the Supreme Court upheld the segregation laws, solidifying the legality of racial discrimination for decades.