 His first argument rests on his empiricist conception of reason. As we saw in his account of causation, demonstrative reasoning consists in comparing ideas to find relations among them, while probable reasoning concerns matters of fact. He considers mathematical reasoning from the relation of ideas category and causal reasoning from the category of matters of fact. He asks us to look at instances of actions where these two types of reasoning are relevant and says that when we do, we will see that reason alone couldn’t have moved us.