combated through the non-philosophical adherence to custom or habit. He ends the section with his own reservations towards Cartesian and Lockean epistemologies. In the second section he returns to the topic of hard skepticism by sharply denouncing it. "For here is the chief and most confounding objection to excessive skepticism, that no durable good can ever result from it; while it remains in its full force and vigor. We need only ask such a skeptic, What his meaning is? And what he proposes by all these curious researches? He is immediately at a loss, and knows not what to answer... a Pyrrhonian cannot expect, that his philosophy will have any constant influence on the mind: or if it had, that its influence would be beneficial to society. On the contrary, he must acknowledge, if he will acknowledge anything, that all human life must perish, were his principles universally and steadily to prevail." (Hume 1974:426) He concludes the volume by setting out the limits of knowledge once and for all. "When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion." Critiques and rejoinders The criteria Hume lists in his examination of the validity of human testimony are roughly upheld in modern social psychology, under the rubric of the communication-persuasion paradigm. Supporting literature includes: the work of social impact theory, which discusses persuasion in part through the number of persons engaging in influence; as well as studies made on the relative influence of communicator credibility in different kinds of persuasion; and examinations of the trustworthiness of the speaker. The "custom" view of learning can in many ways be likened to associationist psychology. This point of view has been subject to severe criticism in the research of the 20th century. Still, testing on the subject has been somewhat divided. Testing on certain animals like cats have concluded that they do not possess any faculty which allow their minds to grasp an insight into cause and effect. However, it has been shown that some animals, like chimpanzees, were able to generate creative plans