Logical reasoning PrepTest 147 · Section 4 · Question 21

Incorrect. For the analogy to work, organs and machines have to be, well, analogous—that's not the same as organs being machine-like in their nature.

Incorrect. The conclusion of this argument relies on physics and chemistry not being able to fully describe the nature of a machine or organs. As such, the analogy only needs to highlight ways that these sciences fail. Since the conditions required for success are noted as a success of physics/chemistry in analyzing machines, they're actually not a part of the logic leading to the conclusion, and so they don't need to be a part of the analogy.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Analogy - Only engineering can analyze the nature of machines in terms of success, as only physiology can analyze organ's in terms of healthy function, as Machine side: Physics/chemistry fail - Can determine material conditions for success; Can't express purpose
Organ side: Physics/chemistry fail - Cannot ascertain operational principles
Answer Anticipation:
Note the very interesting wrinkle in this question stem—it's asking for a necessary assumption for the analogy. As such, we should make sure we understand the related elements, as the correct answer will highlight something that isn't fully connected.

Here, engineering and physiology are analogized as the only sciences that can analyze something—a machine for engineering, and the body/organs for physiology. In both sides of the analogy, physics and chemistry are ruled out as being able to fully analyze these things.

Digging into that analogy, we see that, on the machine side, the stimulus notes things chemistry can determine and things that it can't. Since the conclusion is that chemistry/physics can't analyze the nature of a machine—only engineering can—what these two sciences are capable of is out of scope. Instead, it must be what they can't do that is relevant. As such, what they can't do must also have an analogue in the physiology/organ scenario. Since the analogy itself never states that physics/chemistry can't account for the purpose of organs (instead talking about operational principles), the correct answer is going to have to make that connection.

Answer Explanation:
This answer highlights that, for the analogy to work and show that physics/chemistry can't analyze the nature of a machine, physics/chemistry have to be unable to analyze the equivalent nature of organs. Since the argument relies on a lack of ability to describe purpose in machines, the analogy requires that an analogous concept exists for organs—otherwise, it doesn't apply to the relevant consideration that leads to the conclusion.

Key Takeaway:
When an argument relies on an analogy, be sure to "match up" the pieces to see how it works. From there, note any missing pieces if there are any, as they're probably related to the correct answer.

Incorrect. As long as physiology covers material that physics/chemistry don't, it doesn't matter if they overlap partially.

Incorrect. The argument doesn't require that biological processes to be irreducible to mechanical/chemical properties (physics/chemistry, respectively)—it just needs those fields to be unable to describe some portion of the purpose of these organs, as they can't with machines.