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Thank you for your help and patience.
And wow, that is a really good example that you just gave. Exactly what I was after
It fails to satisfy rule six not because the P is undistributed in the conclusion and distributed in the major premise but because the R term is distributed in the conclusion and undistributed in the minor premise. Have I understood once and for all?
So if the propositions were switched around to make the new order:
Then that would be a violation of rule six because we are moving from an undistributed term [B] in one of the premises [BIC] to a distributed term [B^] in the conclusion [BAD]
so whenever you’re limiting the scope (going from a full scope [in one or more of the premises] to smaller scope [in the conclusion)) then that’s cool/valid, but when you’re enlarging the scope (going from a smaller scope [in one or more of the premises] to full scope/extension [in the conclusion]) then that’s not cool/invalid
am I on the right track?
I just realise that this is a bad example because it violates rule 2
Is there any chance that you might be able to come up with some better examples than the one I just gave which would explain the point more accurately and help make it a little clearer?
“If you have any other queries or questions, please do let me know. And if you start a thread, please send your initial post directly to I might not see it for some time.”
How would I go about sending a link/message directly to you?
“Thank you, David. This came up before and I posted a correction in the thread ‘Errata’ but since someone might miss the correction, I’m redoing the lesson and it will be reposted. Here’s what I said in the Errata thread:”
Thank you for the response, I’m brand-new to liberty classroom and so have not had a chance to check out all the threads, I’m sure I would have come across this if I had done some digging.
Having spotted the mistake I thought it a good excuse to make my first contribution to the forum.
All the best.
Also in the video ‘how much do you know?’ At 11.00 when referring to question 6. Gerard makes the same mistake
a) BAC, ???, BID
“Of the four remaining candidates, the only one in which C is distributed is CAD, since rule six is vacuously satisfied, the proposition CAD satisfies all the rules and will give us a valid syllogism. ”
However this is not a valid syllogism because the B term is distributed being the subject term in the universal affirmative proposition yet the B term is undistributed as the subject term in the particular affirmative proposition that is the conclusion to the syllogism. Rule six is not satisfied (no term can be distributed in the conclusion that is not distributed in the premise) and since all six rules must be satisfied in order for a syllogism to be valid, this syllogism is invalid.
In the video ‘exercises in construction’ at 5.42 (when discussing the solution to question 5) Gerard makes a mistake.
“5. MIN, NER, conclusion?
Let’s eliminate the compliment in the second premise by using obversion, giving us NAR
our fragment is now: MIN NAR, conclusion?
The middle term is N, so the terms in the conclusion must be M and R
Since we have no negative premises we can rule out a negative conclusion; and since one of our premises is particular, we can rule out a universal conclusion, leaving us with MIR/RIM
However, the middle term is N and N is distributed in neither premise so no valid conclusion is possible”
This last sentence is false (this is where the mistake occurred) N is in fact distributed in the proposition NAR, this being a universal affirmative proposition it distributes its subject term, which in this case is N. So the assertion that “and N is distributed in neither premise” is false.
MIR is in fact a valid conclusion to the syllogism since it accords with all six rules.