FOM: Questions about Polya's "Plausible Reasoning"

[D. E. (Steve) Stevenson]

Happy New Year to all:

George Polya in [1] makes two statements that are not attributed. I am
interested in knowing the references.

1. He has a long quote from Aristotle "A syllogism is a discourse in which,
certain things being stated, something other than that what is stated
follows of necessity from their being so."

2. He lists four attributes of syllogisms as impersonal, universal,
self-sufficient, and definitive. I assume this is standard, but where do
these properties come from? What alternatives might be considered standard?

Best,

steve

[1]	George Polya. Mathematics and Plausible Reasoning. Volume 2: Patterns
of Plausible Reasoning. Princeton University Press. 1954. Chapter 15. pages
112-113.