Kant believed that it was possible to make synthetic a priori judgments. This provides a large portion of human knowledge. He believed that Hume's arithmetic and geometry gave the basis for natural science to be able to explain and predict events. Hume believed that the contents of the mind are based on two different kinds. Ideas come from the send impressions or experience and the relations of ideas that can be exemplified such as mathematics. "Only statements concerning relations of ideas can be necessarily ture. Hume argued that the idea of Necessary Connection is part of the idea of cause and effect, but experience can never be the source of that idea. Experience shows the constant conjunction of cause and effect. We cannot have knowledge without cause and effect. Kant believed that synthetic a priori judgments were based on human knowledge.