Broadly construed, examples of properties include redness, the property of being two, the property of being nonexistent, the property of being identical to Socrates, the property of being a desk, the property of being a property, the property of being both round and square, and the property of being heterological. Some philosophers refuse to treat existence as a property, and Peter van Inwagen suggested that one should deny the existence of certain “properties” so as to avoid paradoxes such as Russell’s paradox and Grelling–Nelson paradox, though such moves remain controversial.