Born in Ireland in 1945, Scully was raised and educated in London. In 1975, he moved to New York where he was immediately influenced by the geometric and color field painters working in that city: Barnett Newman, Ad Reinhardt, and, especially, Mark Rothko. Abandoning the figurative work he was pursuing at the time, Scully began working with the deliberately reduced set of motifs that have occupied him for the last twenty plus years.
Scully gathers his motifs from everyday experience; he looks at doors, windows, road maps, and uses photography "as a means of defining the parameters of his own visual world". He does not depict the world but finds in the world visual experiences that correspond to his artistic mission, one that seeks to portray the richness of human experience.
To Scully, this humanism is expressed through color; more explicitly, through the relationships between the colors of his characteristically dark and understated palette. The reduction of formal elements to stripes and squares allows the color relationships to be of utmost importance. In the indefinite transition zones between colors, Scully exposes the "mystery of ambivalence and uncertainty" that permeate the human experience.