Three Dialogues between Hylas and Philonous

Hylas meets Philonous the next morning, and the conversation picks up where the two left off. Hylas mentions that he has been dwelling on the previous day’s conversation and wrestling with many of the concepts Philonous raised. Hylas thinks he has discovered a possible way of refuting Philonous and discusses what the science of the day understood about the brain and the rest of the central nervous system—that the brain is the source of sensations caused by external objects. Philonous disputes Hylas’s apparently scientific analysis. Philonous argues that the brain conceives of itself as a brain. Since it cannot be directly experienced through the senses, the brain is an idea like any other idea. After Philonous pushes back against Hylas, the latter is now at a complete loss for further rebuttal. Hylas concedes that Philonous has proven him a skeptic; however, he also insists that Philonous is likewise a skeptic. Philonous again insists that he is not a skeptic. He repeats his claim that objects only exist inside the mind that perceives them, yet they do exist. The materialist contention that objects exist outside the mind, in Philonous’s view, is actually a denial that they exist at all.