Technology Rig Some days you wish had never started, then along comes one you hope will never end. Anything can happen in a day.

The Main idea of the Book is amazing, Subjective idealism or immaterialism in which only minds and mental contents exist and we are all ideas in the mind of a perceiving God. But most of the arguments presented by Berkeley to support his case are terrible and wrong. I'll give a few examples:

His Master Argument to demonstrate that it is inconceivable for an object to exist outside of a mind:

In order to conceive if it is possible for a tree to exist outside of all minds, we need to be able to think of an unconceived tree. But as soon as we try to conceive of this unconceived tree, we have conceived it in our mind. So we have failed to conceive a tree to exist outside of all minds.

Berkeley mixes between conceiving which is an act of the mind and the content of the conception which can either be real or not.

To Prove that matter can't cause ideas or perceptions in the mind:

1. Matter is unthinking and inactive.
2. An inactive substance cannot be the cause of an actual perception in the mind, which is active. 
3. Only another Mind can be the cause of our thinking. 

The Relativity Argument:

Size is not a quality of an object because the size of the object depends on the distance between the observer. Since an object is a different size to different observers, then size is not a quality of the object. Berkeley rejects shape with a similar argument.

Yes, experience is subjective, but is your experience of the size of an object is the same as the size of the object in-itself? Berkeley's assumption that they are the same is the source of confusion.

To Prove only ideas are the objects of our perceptions, not "things themselves."

1. If something is indistinguishable from a pain, then it is a pain.
2. A great degree of heat is indistinguishable from a pain. 
3. So, a great degree of heat is pain. 
4. If a pain cannot exist unperceived, no great degree of heat can exist unperceived. 
5. If external objects are not the subject of sensations or perceptions, pains and heats cannot exist in external objects. 
6. So, pains and heats cannot exist in external objects. 
7. Since pain exists in the mind only, heat also must exist in the mind only. 

To prove that matter isn't an instrument used by god:

1. If X is an instrument, then X is a tool used by a creature to do something that creature couldn't do without it. 
2. God uses instruments (matter) to cause perceptions. 
3. Thus, God uses tools to do things that otherwise he wouldn't be able to do. 
4. But God is omnipotent and so can do anything without tools.
5. (3) & (4) are together a contradiction, so one of them must be false. 
6. (4) is definite, so (3) is false. 
7. So God does not use matter as an instrument.