There is an ongoing debate in philosophy of mind and epistemology about whether perceptual experience only represents those “thin” features of our environment that are apprehended by our senses, or whether, in addition to these, at least some perceptual experiences represent more complex, “thick” properties. My aim in this paper is to articulate an important difference between thin and thick properties, and thus to diagnose a key intuitive resistance many proponents of the thin view feel towards the thick view. My (...) diagnosis then provides us with a novel and compelling argument against the thick view. In what follows, first I consider two unsuccessful versions of an alternative strategy against the thick view found in the literature. Next, I present my own argument. The argument involves proposing two constraints on the phenomenal contents of perceptual experience, which I call the Presentation Principle and the Containment Principle, and then reasoning from these principles to a conclusion that is fatal to the thick view—an outcome that I call the problem of Phenomenal Explosion. I conclude by responding to several objections. (shrink)