Conditional Reasoning: Diagramming this statement correctly.

chia99
Posts: 31
Joined: Sun Apr 11, 2010 5:03 pm

Conditional Reasoning: Diagramming this statement correctly.

Postby chia99 » Wed Sep 07, 2011 4:56 pm

So this is a portion of the stimulus that contains conditional reasoning and when drawing out my sufficient and necessary conditions diagrammed a mistaken reversal.

"Therefore, the only effective way to reduce such emissions is to replace the conventional diesel fuel and gasoline used in automobiles with cleaner burning fuels such as methanol that create fewer emissions."

When I diagrammed this my diagram looked like this:
Replace-->Effectively Reduce Emissions

While the correct diagram should have been:
ERE-->Replace

The presence of the "only" before effective way to reduce... tripped me up to make me think that it was the necessary conditions.

Any advice on how this type of error could be avoided?

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Bobeo
Posts: 108
Joined: Tue Apr 05, 2011 7:51 pm

Re: Conditional Reasoning: Diagramming this statement correctly.

Postby Bobeo » Wed Sep 07, 2011 6:14 pm

"The only" introduces sufficient. "Only" introduces necessary.
Last edited by Bobeo on Wed Sep 07, 2011 7:43 pm, edited 1 time in total.

utopian_grrl
Posts: 39
Joined: Wed Jul 14, 2010 2:48 pm

Re: Conditional Reasoning: Diagramming this statement correctly.

Postby utopian_grrl » Wed Sep 07, 2011 6:42 pm

"the ONLY effective WAY to reduce such emissions is to replace the conventional diesel fuel and gasoline used in automobiles with cleaner burning fuels such as methanol that create fewer emissions."

"Only" does introduce the necessary in the conditional.
But, in this case, the necessary introduced is the "way."
So ask yourself: what way is used to reduce emissions

A rephrase:
If you want to effectively reduce emissions, then you must replace the conventional diesel fuel and gasoline...

That's just how I personally look at the question.

dakatz
Posts: 2460
Joined: Sat Mar 29, 2008 4:19 pm

Re: Conditional Reasoning: Diagramming this statement correctly.

Postby dakatz » Wed Sep 07, 2011 6:44 pm

The phrase "the only" introduces a sufficient condition, whereas the phrase "only" on its own would indicate a necessary condition. That is why the correct diagramming is the opposite of what you originally though. Just remember the difference between "only" and "the only" and you will be fine.

chia99
Posts: 31
Joined: Sun Apr 11, 2010 5:03 pm

Re: Conditional Reasoning: Diagramming this statement correctly.

Postby chia99 » Fri Sep 09, 2011 5:01 pm

I didn't know that about "the only" that will definitely help me out now. Thanks guys.




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