Powerscore Drill question- Weekend Course

[voodoochild]

Experts,
I am lost with this one:- Page 270 Question #9 - "Unless the stock market rebounds, the economy will not recover this year."

This also means, if the stock market doesn't rebound, the economy will not recover this year. (I have got rid of "unless" and substituted "if-else" for clarity) ...equation (0)

Now, let's go to the diagramming world by representing equation (0) :- ~(Stock market rebound) ~(economy will recover) .....Equation (i)

Contrapositive of equation (i) : economy recover stock market rebound ....Equation (ii)

Now, because Equation (i) and (ii) are the same (they are just contrapositives), the negation should yield the same result.

Negation of Equation (i) -- ~(Stock market rebound) (economy will recover) OR if I take contrapositive, ~recover rebound ...equation (iii)

Now, let's take negation of Equation (ii) : economy recover ~stock market rebound ....equation (iv)

If we compare equation (iii) and (iv), both the equations are 180 apart. What am I missing here? Please help me?

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To shorten, we know that if a b then ~b ~a is the contrapositive.

However, if I negate a b to get a ~b, and then take a contrpositive, I will get b ~a.

Similarly, if we negate ~b ~a to get ~b a, then this is completely different from the above negated version. Even though we started from the same equation, and the same contrapositive.

Help?


Thanks

[Dave Killoran]

Experts,
This also means, if the stock market doesn't rebound, the economy will not recover this year. (I have got rid of "unless" and substituted "if-else" for clarity) ...equation (0)

Your problem is right there--you've reworded the original statement into something that it doesn't say.

Two things here:

First, "unless" doesn't turn into "if else," so be careful there! Instead, you can use "if not." However, I prefer not to use that translation as it usually produces a diagram with two negatives, which is harder for most people to work with.

Second, why not just use the Unless Equation to process this statement--once you've used it a few times it becomes second nature, and it will typically produce the most usable diagram (meaning: no negatives) out of statements including "unless, "except, "until," and "without. Applying that process would have allowed you to diagram this properly as:

Economy Recover Stock Market Rebounds

Please let me know if that helps. Thanks!