3.4.3: Skepticism

In all of the above discussions on epistemological topics, Hume performs a balancing act between making skeptical attacks (step 1) and offering positive theories based on natural beliefs (step 2). In the conclusion to Book 1, though, he appears to elevate his skepticism to a higher level and exposes the inherent contradictions in even his best philosophical theories. He notes three such contradictions. One centers on what we call induction. Our judgments based on past experience all contain elements of doubt; we are then impelled to make a judgment about that doubt, and since this judgment is also based on past experience it will in turn produce a new doubt. Once again, though, we are impelled to make a judgment about this second doubt, and the cycle continues. He concludes that “no finite object can subsist under a decrease repeated in infinitum.” A second contradiction involves a conflict between two theories of external perception, each of which our natural reasoning process leads us to.  One is our natural inclination to believe that we are directly seeing objects as they really are, and the other is the more philosophical view that we only ever see mental images or copies of external objects. The third contradiction involves a conflict between causal reasoning and belief in the continued existence of matter. After listing these contradictions, Hume despairs over the failure of his metaphysical reasoning:

The intense view of these manifold contradictions and imperfections in human reason has so wrought upon me, and heated my brain, that I am ready to reject all belief and reasoning, and can look upon no opinion even as more probable or likely than another [Treatise, 1.4.7.8].

He then pacifies his despair by recognizing that nature forces him to set aside his philosophical speculations and return to the normal activities of common life. He sees, though, that in time he will be drawn back into philosophical speculation in order to attack superstition and educate the world.

Hume’s emphasis on these conceptual contradictions is a unique aspect of his skepticism, and if any part of his philosophy can be designated “Humean skepticism” it is this.  However, during the course of his writing the Treatise his view of the nature of these contradictions changed. At first he felt that these contradictions were restricted to theories about the external world, but theories about the mind itself would be free from them, as he explains here:

The essence and composition of external bodies are so obscure, that we must necessarily, in our reasonings, or rather conjectures concerning them, involve ourselves in contradictions and absurdities. But as the perceptions of the mind are perfectly known, and I have us’d all imaginable caution in forming conclusions concerning them, I have always hop’d to keep clear of those contradictions, which have attended every other system [Treatise, 2.2.6.2].

When composing the Appendix to the Treatise a year later, he changed his mind and felt that theories about the mind would also have contradictions:

I had entertained some hopes, that however deficient our theory of the intellectual world might be, it wou’d be free from those contradictions, and absurdities, which seem to attend every explication, that human reason can give of the material world. But upon a more strict review of the section concerning I find myself involv’d in such a labyrinth, that, I must confess, I neither know how to correct my former opinions, nor how to render them consistent. If this be not a good general reason for scepticism, ’tis at least a sufficient one (if I were not already abundantly supplied) for me to entertain a diffidence and modesty in all my decisions [Treatise, Appendix].

Thus, in the Treatise, the skeptical bottom line is that even our best theories about both physical and mental phenomena will be plagued with contradictions. In the concluding section of his Enquiry, Hume again addresses the topic of skepticism, but treats the matter somewhat differently: he rejects extreme skepticism but accepts skepticism in a more moderate form. He associates extreme Pyrrhonian skepticism with blanket attacks on all reasoning about the external world, abstract reasoning about space and time, or causal reasoning about matters of fact. He argues, though, that we must reject such skepticism since “no durable good can ever result from it.” Instead, he recommends a more moderate or Academic skepticism that tones down Pyrrhonism by, first, exercising caution and modesty in our judgments, and, second,  by restricting our speculations to abstract reasoning and matters of fact.