In the case of black knit tie; I have always wondered why it is more versatile than navy? Starting out I always thought you never needed a black tie except for 'black tie'; also that it was always preferable to get a navy. While I myself have never owned a black knit (heresy I have always wondered why everyone think they are the most versatile; is it a trad thing? Don't get me wrong I do enjoy the aesthetic but why black>navy for knits when usually it's always navy>black for most ties?
As someone else mentioned - it might defy some laws but the black knit tie is a basic and at the same time an element of the advanced class. I think Stephen Hawking has written about it in his book on TIME.
Black is a non colour. It doesn't reflect or emit light. So that as a small area - as in a tie - it doesn't draw attention to itself. A desirable attribute at times for a tie. Think of its opposite - the shiney, satin, bright yellow tie of the Real Estate Agent or "Power Dresser" combined with a dark suit and white shirt.
Black has at times been a symbol of austerity (Dutch Protestants), withdrawal from the material world, (priests, nuns, puritans), power, (priests, Nazis, police) and artistic tendencies (architects, artists, Melbourne hipsters) and many other signals. It retains, to an extent, many of these meanings, sometimes all at once, depending on the contexts.
Theres nothing wrong with black (even in a suit) but it can be dodgy - too shiny or too much green caste etc etc . Black needs texture and variation to work well. Shiney black suits = no. Black cords and leather jacket =perhaps.
Black knit ties give texture and interest without attracting attention..