[FOM] FOM: Set theory and ordinary language
Richard G Heck
heck at fas.harvard.edu
Sat Dec 28 15:26:07 EST 2002
Dean Buckner wrote:
>Consider ordinal descriptions, such as "the first man", "the second man",
>"the third man" and so on, as they are used in ordinary language. Suppose we can show that any sequence of such expressions (a) has a linear ordering (b) has a first member (c) has a "last" member (d) contains no "limit ordinal", ie. contains no ordinal without a direct predecessor. Does this then guarantee that the sequence determines a finite set, and thus a set which is well-ordered, and thus a set to which for which finite induction is automatically valid)?
No. An ordering of the form omega + -omega will satisfy these
conditions. So, for example, the set:
satisfies all of your conditions. There is a general reason to be
suspicious: The four conditions can be specified as a single first-order
sentence (which will, of course, be a conjunction, but nevertheless).
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