What makes people irrational thinkers?

[polymath257]

this bit stood out to me:


"Physical reality cannot account for its own existence for the simple reason that nature—the physical—is that which by definition already exists; existence, even taken as a simple brute fact to which no metaphysical theory is attached, lies logically beyond the system of causes that nature comprises”. 

I think that by "account for its own existence" he means that there is nothing within nature which explains why it exists to begin with. Science describes the causes and effects within nature, but not the cause of nature itself.

To say that nature causes itself, you'd need a strange argument: 

 ~ First no part of nature existed.
 ~ Then a part of nature caused nature to exist. 

If time began with nature, the first statement is false.

Obviously if no part of nature existed, then there is no part of nature which can cause nature to exist. So if someone thinks that nature has a cause, then it needs to be a cause which isn't part of nature. 

So the quote from Hart above seems true to me, although it doesn't go all that far. It just means that the system of causes within nature aren't sufficient to explain why nature is here. 

1. Hart hasn’t shown here that physical reality can’t be causeless and necessary. 

He certainly hasn't in the quote above. Does he address the issue elsewhere in the book? 

2. If nature cannot account for itself by the fact of its very existence, then this seems to also be a problem for God’s existence accounting for itself.

This, too, isn't addressed in the brief quote you give, but is something for which there are other arguments. Very roughly, the idea is that things which can't be self-caused are contingent, and therefore must rely on something necessary. 

If God were seen as a Demiurge or craftsman -- some other contingent, active thingy which puts together nature -- then you're right the same question would be appropriate. What made the Demiurge? Hart's argument is that God is unique in that it is non-contingent and unchanging. It is unlike the material created world in that its essence is identical with its existence. And there are elaborate arguments as to why such a thing is necessary for contingent existence to continue.

So you're certainly right that none of this is addressed in the quote you give, and that reading just the quote we are left with lots of questions. There's a lot more to the book, though.

Can you give quotes where these issues are addressed?