Fitzgerald uses irony.Tom speaks of the uncivilized, those who are not white.He uses an air of superiority when he is the one who is not being civilizad at all.If he was born with all the advantages he had, why should he feel threatened by inferior races' At the same time , the whole idea of judging people by the colour of their skin is uncivilized.He uses violence to have the control of things.Again he is being almost primitive in not accepting different people, specially because he presents himself as a superior being.