One must establish that a thing is possible before one can begin the inquiry into the conditions of its possibility. One may, of course, assume the existence of the thing as a fact; but in an area where there is disagreement, there is at least a preliminary task that must be faced: that of answering the opposing arguments. Husserl meets these necessities in the "Prolegomena" to the Logische Untersuchungen. In a rather curious method of procedure, he argues that objective knowledge is possible because the denial of objective knowledge is not possible. More concretely, he may be regarded as arguing that any theory which denies the possibility of objectively valid knowledge slips into relativism. Relativism itself, however, collapses into scepticism — a position which undermines the possible validity of the original theory.