1. Sensible Qualities
Things like heat ARE qualities that are subjective. These are secondary qualities. Everyone agrees that secondary qualities DO have mind dependency.
Berkeley goes on to show that primary qualities such that SHAPE etc, ARE ALSO subjective in nature. He starts of this argument with agreed upon points.
Agreed upon points:
We perceive things immediately by our senses.
These things we immediately perceive are the sensible qualities of the object.
Philonous' Strategy (The “hero” who Berkeley uses to prove his point of mind dependency of ALL sensible qualities be they primary or secondary).
e.g.: the arguments from perceptual relativity.
So colours, sounds, smells, shapes, extension, motion, solidity, solidity have no existence independent of our perception of them.
There is NO distinction to be made between a sensibly quality and the idea we have of said quality.

2. Hylas' Strategy
Hylas is the “other guy”. The materialist, who comes up with possible objections to Philonous' view's.
Hylas tries to convince Philonous that the mind-dependent qualities are only the “apparent” version of a quality, the “real” versions reside elsewhere.
The latter quality lies in the object, and IS objective, what we perceive is a subjective “version” of the objective real quality.
e.g.: Though apparent sounds are mind dependent, real sounds are not.
e.g.: Though apparent colours are mind dependent, real colours are not (real colours inhere in the motions of a subtle substance, light, reflecting off a solid surface).
Philonous' Response:
Hylas' view is paradoxical. Since they seem to suggest that the real versions of the sensible qualities are never perceived as they are.
So we never actually hear the sound of something. This is quickly plunging towards scepticism now.

3. More of Hylas' Strategy The act/object distinction (p.427):
In Philonous' philosophy there is NO distinction between a mental act, and the object of said act.
The sensations (sensory ideas) are, for e.g.; acts of mind, whereas the qualities are objects of those acts.
Is there a distinction between the sensations we have of the object (act) and the object or qualities that “cause” those ideas (object).
e.g. A tulip: The sensations of red and yellow are mental acts, but to Hylas the qualities themselves are of the tulip.
Philonous' Response:
The only object seen consists in the combination of sensible qualities we actually perceive. These qualities just ARE the sensations. They are just a combination of ideas.
Further, the mind is actually passive in its reception of sensibly qualities.
Conclusion in cases of perception, there is no viable distinction between act and object.

4. Berkeley's Immaterialism
Berkeley's idealism: Only minds and ideas exists
Berkeley's immaterialism: there is no such thing as matter (material substance).
A portrait of matter:
Mind independent. (i.e. does not depend upon perception).
Unthinking (doesn't possess powers of thought or perception)
It is the substratum of various qualities. (i.e. it is the “thing” that contains various qualities).
The cause of our sensations.

5. Against material substance
Hylas mantains that the qualities we percieve cannot exist without inhering in a material substance or substratum.
Material substance (or substratum):
“It is not in sensible, its modes and qualities only being perceived by the senses”. i.e.: It (material substance) is only perceived via its modes and qualities, and not by itself.
Thus, It is known only in relation to sensible qualities, since that is the only way we can perceive substance.
It is something that underlies (or stands under) the sensible qualities.
Philonous' argument (429):
No sense can be given to the relation of underlying or standing under (material substance), sensible qualities like extension, or shape.

6. Against material substance
Argument 2:
The very notion of a mind independent object is “inconceivable”
Hylas wants to say that we CAN conceive of material objects as existing independently of any mind's perception.
e.g. a tree or a house existing while no one is looking at it.
Philonous' response: It IS a contradiction to say that we can conceive of something that is unconceived.
When you try to conceive of something that is “unconceived”, it is NOT unconceived anymore since you have now conceived of it.
Against representational-ism:
representational-ism: our sensory conceptions are inner representations of material objects, that said objects cause.
since we are only aware of our own ideas in sensation, the supposed material objects are not something we can sense.
The idea of “resemblence” between our ideas and material objects is hopelessly confused
Ideas: inner objects, fleeting, variable
material objects (supposedly): external, stable, unvarying.
Our ideas are sensible, but since mat. objects are non-sensible, how can they resmble our ideas?
Conclusion: we simply don't have any conception of mind independent objects. Believing in them leads to scepticism.

7. Minds, Ideas and Causality
Hylas tries out the mechanistic hypothesis that all our sensations are effects (traces) in the brain cuased by motions conveyed through the nerves, and so on...
What do we mean by the brain?
Philonous
The brain is a sensible thing.
All sensible things are ideas
Therefore the brain is just an idea (or complex one thereof)
Thus a sensation is an idea, in an idea. Which is an absurd veiw.
The mechanistic view is broken in the first place.
We have no concept at all of how motions could give rise to sensations of colours and such.
Ideas themselves are causally inert.
Some ideas are caused by the activities of our own minds.
e.g.: Ideas of imagination.
Not all ideas are like this.
The vivid, distinct, orderly ideas received through sensation must therefore be caused by another spirit.
God is Berkeley's explanation of the relative permanance of “real things”.