> When we derive the consequences of a theory, we introduce new
concepts — protons, molecules, stars — because they are
convenient
Couldn't matter itself be just another "human", "convenient" concept? Indeed the author writes:
> our external physical reality is assumed to be purely mathematical
Why should a purely mathematical reality also be material? Doesn't this lead to the logical conclusion that ideas, err, maths is "all that there is"?
Sure, in this case ideas are objective and not subjective, but Berkeley's "mind of God" argument also leads to an objective, albeit immaterial reality, doesn't it?
>Sure, in this case ideas are objective and not subjective, but Berkeley's "mind of God" argument also leads to an objective, albeit immaterial reality, doesn't it?
No, it leads to a subjective inability to know anything at all. It's a difficult philosophical view to talk about, because the people espousing it can not possibly actually believe it and usually don't even understand it. The non-existence of a shared, knowable, objective reality means that, even in a totally solipsistic model, inductive reasoning can not be applied. You can not assume that attempting to breathe in the next moment will extend your life rather than extinguish it. You can not conclude that the air in your lungs will not suddenly become ants. You certainly can not leap to the extensively complex chain of reasoning necessary to believe that between this sentence and the next the English languages will turn into French. It introduces aggressive, pervasive, impossible-to-dismiss inconstancy in all things, including ones self.
A true believer in a subjective universe would remain still in their bed, doing nothing, until they died. Any action whatever beyond automatic biological functions instantly betrays their belief that they know their body, know the environment they are in, and know how the mental activity necessary to cause the action will elicit a change in the environment which is not likely to destroy them. And that is a thing they can never know in a subjective universe.
The 'mathematical universe' on the other hand is simply discussing how the shared, knowable, material universe we live in came to be or is best understood. I happen to think it is factually wrong on a few points (the author just off-hand claims that if we had a big enough supercomputer we could exactly calculate the future development of the universe which is fundamentally untrue for one) but it certainly doesn't amount to subjectivity.
1) But convenience is objective! (It is not convenient to sit in a chair that is hanging upside down.) Which is why matter, even if it is seen as a "convenient" mental construct, is still objective.
2) Materialism and "objectivism" are closely tied together. Mathematics consists of abstractions (or models), and those reside, in particular, in our mind; being "convenient", these abstractions are therefore reflections of what lies outside, and so - almost by definition - the objective world itself, matter, cannot possibly be built from math. (Besides our mind, "abstractions" can also reside in other, inanimate, objects; regardless, this still means that some part of matter merely reflects, to a degree, some other part).
> When we derive the consequences of a theory, we introduce new concepts — protons, molecules, stars — because they are convenient
Couldn't matter itself be just another "human", "convenient" concept? Indeed the author writes:
> our external physical reality is assumed to be purely mathematical
Why should a purely mathematical reality also be material? Doesn't this lead to the logical conclusion that ideas, err, maths is "all that there is"?
Sure, in this case ideas are objective and not subjective, but Berkeley's "mind of God" argument also leads to an objective, albeit immaterial reality, doesn't it?