All of the above universes make 
(A camel exists or Francis the talking mule
is an aardvark) TRUE
Now, the first one does it just by making the left disjunct true, (remember your rules for disjunctions), and just plain ignores Francis. (The A circle doesn't have to be crosshatched to make true. I just like crosshatching.) The second one takes care of Francis in the right disjunct, but completely ignores the camels. (Again, the crosshatching is unimportant here. But doesn't it look nice?) Finally, the third and fourth universes both go to the trouble of making both disjuncts true, which also works. (Did you notice that this is an easy sentence to make true?)
Copyright © 2005 by Martin C. Young
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