Black & white are EXTREME colors. They are viewed as the most extreme colors on the color spectrum. There is a dichotomous symbology regarding these two colors. In Western cultures particularly, white is symbolized as good, pure, above reproach, & saintly while black has been demonized as evil, impure, immoral, depraved, sinful, & even debauched.
White is seen as the unsullied, positive color. It is the color of purity & virginity. It is no mistake that the archetypal color for bridal gowns is white. Black, on the other hand, is the negative color. It is a color of mourning & sadness. It is also the color for those who engage in so-called nefarious activities. It is no mistake that white is associated w/ the benevolent while black is associated w/the malevolent.
The symbology of these colors even extend to the celluloid. Heroes, heroines, & other saviors wear white as evidence of their goodness & wholeness. Villains & other devious characters wear black to demonstrate their dastardly & evil behavior. White is the quintessential beauty while black is the quintessential ugliness.
White is seen as positive, even uplifting while black is viewed as the most abject of despair. Whiteness is somehow viewed in a more positive light e.g. white lie-a lie which isn't considered to be so egregious, whitewash- to make something better than it actually is. By contrast, blackness has a very negative connotation e.g. to blackball someone is to prevent him/her for ever working again, to blackmail someone is to bring up negative things from his/her past in order to make him/her acquiesce to the particular powers that be, & blackball is to denigrate, even ruin someone's reputation.