If:
All humans have one common ancestor
Then:
All ancestors have a (one) common human descendent.
In Brett's words:
>>Based on the accepted nature of the first statement, and on the processes of
>>logic (this would be associative? communicative? inductive? deductive?); I
>>would have to say that the second statement is true--at least in theory.
David McF. responds, rightly:
>If all D have an A, then all A have a D? I think there might be something
>wrong with your logic.
Brett responds:
What I was saying was that there is a relationship between D and A so there
is a relationship between A and D. If this relationship is "to have" (as in
ancesters "have" descendents) then no matter which way we state variables,
the relationship remains in a form of it's original (A has D, D has A, D
does not have A...the relationship is a form of has/has not). If ALL
decendents have a common ancester, then all ancesters have something in
common with any one descendent). The stipulations given were "all" and
"one". How does placing the "all" with the A's and "one" with D's affect
the relationship to have/to have not? Seems if the first is true, then a
variation of the second must be true or the relationship is not valid.
Brett,
The relationship is not reversible. If I tell you, "Eva has only one
mother," it does not follow from that that "Eva's mother has only one
child."
David McF. has it right. Prof. Tim, you're trying too hard. You seem to
have found a way for Brett's sillygism to make sense for you (I think I
understand your interpretation as a severe demand on the meaning of
"isosemantic", applied to Brett's statements), but, judging by Brett's
response, it's not the same way Brett understood it.
Eva,
catching up from the weekend