26 Apr
2010
26 Apr
'10
8:31 a.m.
Forgot about this one: Bjorn Buckwalter wrote:
What got me thinking about this was the apparently incorrect intuition that 'and xs' would imply 'or xs'.
No. See, "and" is very close to "for all", and "or" is similarly close to "exists". For example, the statement "all crows are black" means just "this crow is black AND this one too AND another one on the tree is also black AND..." etc. Now, obviously, all real dragons can fly. But it doesn't mean there is such thing as a "real dragon".