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Single Idea 17890

[filed under theme 6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity ]

Full Idea

Some of the standard large cardinals (in order of increasing (logical) strength) are: inaccessible, Mahlo, weakly compact, indescribable, Erdös, measurable, strong, Wodin, supercompact, huge etc. (...and ineffable).

Gist of Idea

There are at least eleven types of large cardinal, of increasing logical strength

Source

Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4)

Book Ref

-: 'Philosophia Mathematica' [-], p.10


A Reaction

[I don't understand how cardinals can have 'logical strength', but I pass it on anyway]


The 6 ideas from Peter Koellner

Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner]
PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner]
Arithmetical undecidability is always settled at the next stage up [Koellner]
There are at least eleven types of large cardinal, of increasing logical strength [Koellner]
'Reflection principles' say the whole truth about sets can't be captured [Koellner]
We have no argument to show a statement is absolutely undecidable [Koellner]