Apples exist. But they don't have a monopoly on existence because there are other fruits in the garden and each one exists. Apples are universal because they exist. But that doesn't mean they are everywhere throughout the universe of existence. Say I write a book about 20 different varieties of apple. The differences are the particular properties we attribute to each variety of apple...red ones, green ones, yellow ones, etc. They can't negate the existence of apples because they don't exist and the apples do. Each time you read the word "apple" it can find it's meaning in any context in that book. That's what makes it a universal....it's "multi-purpose." True knowledge is the combination of universals, that exist, and particular properties that don't exist. People often differ, argue, disagree and fight about beliefs and for reasons that do not exist. No doubt they make believe these non-existent reasons will harm their freedom. In that case the apples must be made of much stronger stuff and are not so stupid.