#24 - Only if a family manages its finances wisely will it

[tthauvette]

Hi,

Not sure what year this question is from but here it is:

[Question text removed due to copyright restrictions. Question is from February 2000, LR2, #24: "Only if a family manages its finances wisely..."]

The answer choice was (A): Which I got right, but I want to make sure I got it correct for the right reason. Here is the answer:

"Without continued use of pesticides..."

How I chose this answer:

Recognized: Only if as necessary condition, But , So, if, must and the word or. I created a sufficient conditional statement out of fiscal security or workable project — manage finances wisely or realist projections. I negated it. Turned or to and.

This didn't seem to help a whole lot, so I looked at the answers and tried matching the patterns of words "or", "must", "or"," must", "thus", which led me to answer choice (a).

I think there is something I missed in solidifying my answer. Can you please confirm if I should have diagrammed and if my approach was missing something?

thanks, Tania

[Administrator]

We recently received the following question from a user. An instructor will follow up with an answer to this question below.

The answer choice was a: Which I got right, but I want to make sure I got it correct for the right reason. Here is the answer:
"Without continued use-of pesticides it is not possible..."

How I chose this answer:
Recognized: Only if as necessary condition, But , So, if, must and the word or. I created a sufficient conditional statement out of fiscal security or workable project --- manage finances wisely or realist projections. I negated it. Turned or to and.
This didn't seem to help a whole lot, so I looked at the answers and tried matching the patterns of words "or", "must", "or"," must", "thus", which led me to answer choice (a).

I think there is something I missed in solidifying my answer. Can you please confirm if I should have diagrammed and if my approach was missing something?

thanks

[Nikki Siclunov]

Hi!

Thanks for your question!

The stimulus is structured as follows:

Premise 1: Fiscal security Manage finances wisely
(note: "only if" modifies a necessary condition)

Premise 2: Functional budget Realistic projections
(note: "unless" modifies a necessary condition; the remainder is negated to become the sufficient condition)

Conclusion:

Fiscal security Manage finances wisely

OR OR

Functional budget Realistic projections

The conclusion is logically valid. To parallel this line of reasoning, we need two premises, each of which providing a single, independent, conditional relationship (A B; C D). The conclusion combines the two premises using a disjunction (A or C B or D).

This pattern of reasoning should be relatively easy to parallel, as any answer choice that does not have the disjunctive properties of the conclusion (either/or) will be incorrect. Thus, answer choices (B) and (D) are incorrect. Answer choice (C) does not provide for two independent conditional relationships, as the second premise is contingent on the first (it also uses the modifier "some," which makes that statement non-conditional). Likewise, the second premise in answer choice (E) merely clarifies the first; furthermore, the sufficient condition in the conclusion does not have the requisite either/or construction.

A closer analysis of answer choice (A) reveals that it parallels the original argument perfectly:

Grow enough food Pesticide use
Health problems reduced Pesticides harmless
=======

Grow enough food Pesticide use

OR OR

Health problems reduced Pesticides harmless

Hope this clears it up!

Thanks,

[Jonathan Evans]

Tania,

Good job with a challenging question. Good job recognizing necessary and sufficient conditions. I understand your process but suggest that you simplify your approach somewhat in order to avoid possibly making an inadvertent Mistaken Negation or Mistaken Reversal.

Once you recognize that the mechanics involve relationships between conditionals, attack the stimulus piecemeal to derive an accurate description of the relationships. Since there is a lot to keep track of, it may help to make marginal notes of your reasoning.

In this case, start with the first sentence, whence you would obtain the conditional:

fs wm

Thus continue piece by piece to generate:

rp fb

conclusion: fs OR rp wm OR fb

Consider replacing the variables with something more generic and less confusing.

a x
b y
a OR b x OR y

I rely heavily on my ability EITHER to identify necessary conditions by asking myself to spot requirements within stimuli OR to identify sufficient conditions by asking myself to spot guarantees within stimuli. I work piecemeal so I don't get bogged down.

With your prephrasing done, your job is to match.

With answer choice A, the process would work as follows:

pesticides ≡ x
grow enough food ≡ a
harmless pesticides ≡ y
health problems reduced ≡b

Mechanics match precisely with A. Good job getting to the answer. I hope this explanation helps.