Three Dialogues between Hylas and Philonous is a book written in by George Berkeley in 1713.

The most important concepts in the Three Dialogues are: perceptual relativity, the conceivability ("master") argument and Berkeley's phenomenalism. The perceptual relativity argument is that different objects can appear to have different characteristics (e.g. shape) depending on the observer's perspective. Since objective features of objects cannot change without an inherent change in the object itself, then shape must not be an objective feature.

Interestingly, Hylas is understood to represent John Locke, George Berkeley's primary contemporary philosophical adversary. A Hylas is featured in Greek Mythology.

Philonous translates as lover of knowledge and represents George Berkeley. The name Hylas is derived from the ancient Greek word for 'matter' which Hylas argues for in the dialogue.

Three Dialogues Between Hylas and Philonous