Matter is Not the Object of Our Perceptions(1) Sensible things are just those that are perceived by the

senses.(2) The senses perceive nothing that they do not perceive

immediately.(3) So, if something (like a cause) is not perceived by sense, it

can only be deduced by reason.(4) So, sensible things “are nothing else but so many sensible

qualities or combinations of sensible qualities.” (458)

Heat Only Exists in the Mind(1) Pain can only exist in a perceiving being [i.e. not in some

unperceiving material thing].(2) Intense heat is a particular sort of pain.(3) So intense heat can only exist in a perceiving being.(4) If a pain cannot exist unperceived, then no intense heat can

exist unperceived.(5) A pain cannot exist unperceived.(6) So no intense heat can exist unperceived.

(1) A given object cannot have contradictory properties at one and the same time.

(2) To say that an object is both hot and cold at the same time is to attribute to it contradictory properties.

(3) Suppose heat and cold are properties that may actually exist in an unperceiving object, and that we know such an object is hot or cold to whatever degree based on whether it produces sensations of hot or cold in a perceiver.

(4) But the same bucket of water may produce sensations of heat or cold in the same perceiver at the same.

(5) Then (per 3), the same object would be both hot and cold at the same time.

(6) This (per 2) attributes contradictory properties to an object.(7) This (per 1) is absurd, so (3) must be false.(8) So heat and cold are not properties in the object, but only in the

perceiver.

Extension Exists Only in the Mind(1) Color can’t exist without the mind.(2) Extension can’t exist without color.(3) So extension can’t exist without the mind.

Master Argument(4) We can conceive of a house or a tree existing independent of

minds only if we can conceive of that house or tree existing unconceived.

(5) But it is a contradiction to speak of conceiving of thing which is unconceived.

(6) So it is impossible to conceive of a house or a tree [or anything else] existing unconceived.

Proof of God’s Existence(1) “[S]ensible things cannot exist otherwise than in a mind or

spirit.”(2) But, since my sense data are not subject to my will, such

things must “have an existence distinct from being perceived by me.”

(3) So, “there must be some other mind in which they exist.”(4) This mind in which all things exist is God’s mind.

Hylas Tries to Catch Philonous in a Contradiction(1) God is perfect [i.e. not open to being affected].(2) To suffer pain is an imperfection.(3) We are sometimes affected with pain from God.(4) But any ideas in us must come from God.(5) So, the ideas of pain must exist in God—in other words, God

must suffer pain.(6) But, since suffering pain is an imperfection, this means God is

imperfect.