FOM: conservative extensions, correction and sequel

Neil Tennant neilt at
Sun Oct 11 21:46:56 EDT 1998

I think your use of the term "instrumentalism" in connection with conservative
extension results is fine.
Your long list of CE results was very useful; it's good to have the archival
resources to get things like that when one needs them. In this connection,
I'd like to ask you to do us a further favor, if you can find the time. What
about those conservative extension results that relate classical theories to intuitionistic ones? (or even ones based on minimal logic?) Dan Leivant published a nice article in the JSL some time back with results of this kind. Is there any more 
up-to-date and comprehensive summary of C/I/M CE results?
For starters, there's the following improvement by Friedman on a result of

	PA is conservative over HA for all Pi^0_2 sentences.

How about a full list of results of this flavor?

Neil Tennant

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