#22 - All parrots can learn to speak a few words and phrases

[Administrator]

Complete Question Explanation

Must Be True—Formal Logic. The correct answer choice is (A)

Begin by diagramming each of the statements in the stimulus and combining them via any common terms.

The first statement is very straightforward:

• P = parrots
  LS = learn to speak a few words and phrases
  
  P LS

The contrapositive of this statement is probably not useful, since the entire stimulus is about “parrots” rather than “not parrots.”

The second sentence, “Not all parrots have equally pleasant dispositions,” can be diagrammed as:

• EPD = equally pleasant dispositions
  
  P EPD

“Some” statements do not yield contrapositives, but may lead to other inferences. Because the first and second sentences have a common term, P, they can be combined:

• LS P EPD

Since “some” statements are reversible (they can be read from left to right or right to left), the inference from these two sentences is that some parrots that can learn to speak a few words or phrases do not have equally pleasant dispositions. Diagrammatically:

• LS EPD

The statement “Some of those native to Australia can be counted on for a sweet temper” should be diagrammed thus:

• PA = parrots native to Australia
  ST = can be counted on for a sweet temper
  
  PA ST

Since all parrots (native to Australia or elsewhere) can also learn to speak a few words and phrases (from the first sentence), combining this statement with the above “some” statement yields the following:

• LS PA ST

So it can be concluded:

• LS ST

That is, some parrots that can learn to speak a few words and phrases can be counted on for a sweet temper (and vice versa). This is the strongest inference made thus far. Some test takers will recognize this inference and immediately scan the answer choices to find it, and by doing so can find the correct answer without working through the rest of the stimulus. Recognizing powerful inferences like this one can help to save valuable time in Logical Reasoning.

The third statement says, “Almost any parrot will show tremendous affection for an owner who raised the bird from a chick by hand-feeding it.” This statement is a little bit more difficult to diagram than the others. “Almost any” is logically equivalent to “most” and “show tremendous affection for an owner” is easy to represent. Keep in mind the group of parrots to which this statement applies. It is only valid for parrots that were raised from a chick by hand-feeding, so this must be represented this in the diagram.

This is an effective representation:

• PHF = parrots that were raised by hand-feeding
  AO = show tremendous affection for owner
  
  PHF AO

Remember that “most” also implies “some,” meaning that “Some parrots which show tremendous affection for an owner were raised from a chick by hand-feeding.” Since this is true, the following can be concluded:

• LS AO

Please note that “affection for an owner,” “sweet temper,” and “pleasant disposition” are closely related, but are not similar enough to allow for inferences to be made (that is, they cannot be considered common terms).

Answer choice (A): This is the correct answer choice. From the above discussion it should now be clear that some parrots that can learn to speak can also be counted on for a sweet temper. This is the inference made from combining the first sentence and the second half of the second sentence.

Answer choice (B): This statement means that all sweet tempered parrots are either native to Australia or hand-fed as chicks. It also means that if a parrot is sweet tempered and not native to Australia, it must have been hand-fed as a chick. Any of these statements will be a variation of this diagram:

• ST
  + PHF
  PA

There are several problems with this answer choice. Even if “sweet-tempered” is assumed to be equivalent to “shows affection for owner,” this conclusion would still contain a Mistaken Reversal. Furthermore, all that can be known about parrots not native to Australia is that all of them can learn to speak and not all of them have an equally pleasant disposition. Thus this answer choice cannot be inferred from the statements in the stimulus.

Answer choice (C): Most test takers have little difficulty eliminating answer choice (C). Nothing in the stimulus implies that the sweetest tempered parrots are those native to Australia. The author states that some parrots that are native to Australia have a sweet temper, but it is never made clear how sweet these parrots are.

Answer choice (D): This answer choice says that if a bird can learn to speak and be relied on for a sweet temper, it must be from Australia. Here is a diagram:

• LS
  + A
  ST

From the stimulus, the author states that all Australian parrots can learn to speak and some are sweet-tempered. But having these two characteristics does not absolutely guarantee that a given parrot is from Australia, let alone any other bird.

Answer choice (E): Again, very few test takers selected this answer choice. The stimulus deals exclusively with different groups of parrots and one cannot use information about parrots in Australia to make claims about all species of pet birds in Australia.

[amna.ali467]

Hi,

What would the conditional set up for this question look like? I got this question right, I think mostly because the other answer choices were so obviously wrong, but not necessarily because I understood the conditional reasoning set up. So help with that would be much appreciated.

[Nikki Siclunov]

Hi amna.ali467,

Here's how I'd setup the stimulus:

Parrots Speak

Parrots NOT pleasant

Parrots Pleasant (those native to Australia)

Parrots Affection for an owner

Due to the presence of multiple "some" statements in this formal logic stimulus, the only possible inference we can make will also be a "some" statement. This automatically eliminates all answer choices except for answer choice (A):

Pleasant Parrots Speak

For more info on Formal Logic, check out Lesson 8, Supplemental Resources on the Online Student Center.

Thanks!

[rwraulynaitis]

In this question, I mistakenly equated "sweet temper" and "pleasant disposition," but I see that the answer explanation says that these terms, while similar, cannot be considered common terms.

But why not? What is the best way to navigate these distinctions, and is there any strategy or tip that can be applied to similar scenarios in other questions?

Thanks!

[Adam Tyson]

Any distinction between those two terms here would be a distinction without an important difference, rwraulynaitis, so in this case I would say not to worry about whether they mean the same thing or not. The argument never sets us up with a situation of having to choose between treating them as equal terms or not, like giving us an answer that says "some parrots from Australia have a pleasant disposition" and we have to decide whether pleasant disposition and sweet temper are interchangeable or not. The only issue with "pleasant disposition" in this stimulus is that not all parrots have an equally pleasant one - there are differences among parrots, some are more pleasantly disposed than are others.

Generally speaking, you will have to rely on your own understanding of any two similar terms being used. If it's a close call, then any distinction will probably not be central to answering the question, but if they are clearly different, than that difference could be the source of some wrong answer choices, and that's when you need to be very exacting in your thinking.