Three Dialogues between Hylas and Philonous

On the third day, it is immediately evident that Hylas has descended into full-blown skepticism. He argues essentially that nothing can ever be proven, that there will always be limitations to human knowledge, and that because of this, nothing can be said to actually exist. When Philonous points out that he knows he is standing on a rock, Hylas takes exception to the use of the word “know” and further argues that nothing can be fully known in the exact sense of the word.

Philonous, who to this point has made the argument that matter does not exist outside the mind that perceives it, now makes the surprising claim that this is no cause for skepticism. He contends that because his mind perceives objects in the world, these objects are real. Hylas again engages with Philonous on the topic of whether sensible things are real or perceived. The crisis of faith Hylas is experiencing stems from his inability to dispense with this distinction between reality and perception: For Hylas, to be real means to exist outside the mind; therefore if nothing exists outside the mind (as Philonous has convinced him) then nothing is real. Philonous himself has no such difficulty. He maintains that perception is what creates the existence of objects. Philonous also contends that Hylas’s descent into full skepticism, in which he argues despairingly that nothing can fully be known, is due to his insistence that matter exists outside the mind. He says to Hylas, “This makes you dream of those unknown natures in everything” (62-63), and he sees folly in such a perspective, especially compared to his own empirical view of how knowledge is acquired, namely through sensory perception.

Hylas requests to interrogate Philonous so that the latter must now defend his positions against critique. Hylas believes that his line of questioning will lead Philonous into the same kind of skepticism he finds himself in currently. Hylas begins by asking Philonous if the existence of things will survive the event of his death. Philonous assumes that things will still exist because there will be minds to perceive them, in addition to the mind of God that perceives all. Hylas tries a different attack, pointing out that according to his own admission, Philonous cannot empirically prove the mind of God, yet he still accepts that God perceives all things. He then asks why that same logic cannot apply to Hylas’s insistence that matter exists independently. Philonous counters that because his soul is able to produce ideas, and those ideas must come from somewhere, the idea of God is proof that God exists, whereas for matter, the same application of logic will not work. The difference is that the soul or spirit produces the notion of God. Philonous says that only a spirit knows and perceives ideas, and that matter does not have this ability.

Hylas tries to attack the argument by bringing up dreams, asking, “[W]hat difference is there between real things, and chimeras formed by the imagination, or the visions of a dream, since they are all equally in the mind?” (68). Philonous counters by saying that the clarity of thoughts formed by the imagination is weak, unlike the crispness of the image that forms from direct sensory perception. Hylas transitions back to the nature of God. He points out that attributing all ideas to God means that God is ultimately responsible for murder and sin. Philonous disputes this, claiming that sin is not defined by an outward physical act but by the “internal deviation from the laws of nature” (70). Hylas then tries to argue that if the two of them were to go around asking regular people whether matter exists, the average person would conclude that it does, and that Philonous’s views thus contradict common sense. Hylas then turns to the question of faulty perceptions, such as the appearance of a straight oar in the water looking bent. Philonous counters that seeing the bent oar is not a mistake of the immediate sense perception but is one of inference. He uses the analogy of the Copernican system as a means of explaining his point. The Earth spins and revolves around the sun, but since we do not feel that motion while on earth, we correctly conclude that there is no motion. However, removed from the Earth and seeing it from a distance, if we still hold that the Earth does not move, then we make a mistake in inference.

Hylas asks whether Philonous ever believed that matter existed independently of the mind, to which Philonous answers yes, but because of superficial examination of it. Hylas proceeds on a different course, attempting to poke holes in Philonous’s notion by pointing out that since God perceives all things, he likewise allows sin to happen. Philonous objects to this, insisting that sin is internal in the individual and is not an outward physical act.

Hylas continues his attack against Philonous’s position, insisting that by denying the existence of matter independent of the mind, Philonous is denying its reality, to which Philonous retreats to his primary position that matter is only real as far as it can be perceived. It has no absolute existence apart from perception. Hylas continues to try to argue against the premise again and again. Hylas asks, “Doth it not therefore follow from your principles, that no two can see the same thing?” (80). Hylas views this idea as absurd, yet Philonous disagrees. If Hylas is using the word “same” as philosophers typically use it—to signify an “abstract notion of identity” (80), then it is not absurd to think that it is possible for a group of people to see the same thing. This leads to an argument about the nature of language, as Hylas accuses Philonous of twisting language to fit his argument.

Hylas returns to the theological implications of immaterialism. He brings up creation and the book of Genesis, noting that the Earth, moon, stars and the like were created before mankind; this must mean that these things exist outside the mind. Philonous disagrees and explains why immaterialism aligns with the biblical history of creation. He rests his argument on the dichotomy between finite spirits, which exist in time, and God, who does not.

As this section of the text nears its conclusion, Hylas finally uses up all possible objections to Philonous’s argument, yet he is still somewhat reluctant to fully embrace Philonous’s idealist view. Philonous suggests that this may be in part due to deeply rooted biases in favor of materialism, an assertion with which Hylas agrees. As a sort of compromise, Hylas assents to Philonous’s view and accepts that his friend is correct; however, as a condition, Hylas insists on reframing the word matter in order to make better sense of the position. He redefines the word to mean “some sensible thing, whose existence consists in being perceived” (93), which better allows him to accept Philonous’s claims. Finally, as the dialogue concludes, Philonous describes a metaphor of a water fountain in which the water sprays upward to a point only to be pushed back down by gravity. This metaphor serves as an illustration of skepticism.