PrepTest 155

When we see "fails to consider" on an Errors in Reasoning answer choice, the question we should ask ourselves is, "Would this weaken the argument if true?" And the existence of other things composed of just mass and energy wouldn't weaken the claim that physical objects are theoretical constructs. Perhaps those other things are mere theoretical constructs too.

Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
A philosopher says physicists have suggested energy is just a theoretical construct. And the theory of relativity tells us mass and energy are basically the same, so mass must also be a theoretical construct. But physical objects are just mass and energy. So physical objects must be theoretical constructs, too.

Strategy Overview:

1. Argument or facts? Always argument, so identify premises and conclusions of argument
2. Anticipate why the premises are not enough to prove that the conclusion is true. 
   1. Checking to see if a common logical fallacy is committed is very helpful.
3. Use anticipations to select the answer choice that:
   1. Accurately describes the reason why the premises are not enough to prove that the conclusion is true

Answer Anticipation:
As if the LSAT wasn't hard enough, now they have us questioning whether or not we're even real? The good news is, we know from the question type that this is a flawed argument. So, what's wrong with it?

Well, it's relying on a composition fallacy. A whole does not necessarily have all the same traits as its parts, and parts do not necessarily have the same traits as the whole. (For example, hydrogen is an element. Oxygen is an element. But water, which is just two servings of hydrogen plus one of oxygen, is not an element. It's a compound.)

Likewise, mass and energy may be theoretical constructs, but that doesn't mean that physical objects are also theoretical constructs, even if physical objects are merely composed of mass and energy. Perhaps the combination of mass and energy creates a new, non-theoretical whole. The correct answer will point out the composition fallacy here.

Answer Choice Explanation:
Not only does this accurately describe a composition flaw, it even uses the keyword "composed" to make sure we notice. The only hitch here is that "lacking a feature" could throw some test-takers off because we don't generally think of "not really existing" as a feature. But, in this context, "feature" just means "trait" or "characteristic," not "feature" as in, "I love all the features on the latest iPhone." At any rate, this is the only answer choice that describes a flaw in the philosopher's reasoning, so it is correct.

Key Takeaway:
Many test-takers will take issue with the correct answer here, because it relies on us to conceptualize "not being a theoretical construct" as a "lacking a feature." And yes, "being real" is not really a "lacking a feature" in the common, everyday use of the word "feature." Most test-takers would probably be more comfortable picking (B) if said, "It overlooks the possibility that something may be real even if it is composed purely of things that are merely theoretical." But the definition of "feature" is simply "an attribute or aspect of something." And being theoretical certainly qualifies as an "attribute or aspect" of something, even if it's not the physical feature we may initially think of. And if we think of it that way, "not being theoretical" is synonymous with "lacking a feature." In short, on the LSAT, we can't be too picky when a synonym is used. 

By the way, the best way to defend against this is to always use anticipation. If you anticipated that this argument committed a composition flaw and you see that (B) describes a composition flaw, you should pick (B) without hesitation, even if its phrasing is a little wonky.

This describes the opposite of a flaw in the argument. One could argue that a flaw in the argument is "presuming two things cannot have different features even if there is no essential distinction between them." In other words, the flaw could be assuming that physical objects and mass/energy cannot be different. But this answer choice says the argument presumed two things with no essential distinction between them can have different features — which the argument did not, in fact, do.

This is a classic LSAT "blind them with vocabulary" trap answer. However, we can make this relatively simple for ourselves. When we see "fails to address adequately" on an Errors in Reasoning answer choice, the question we should ask ourselves is, "Would this weaken the argument if true?" And different theoretical constructs possessing different features wouldn't weaken this argument. And that's because the conclusion isn't about features of theoretical constructs. It's about whether physical objects are theoretical constructs because they comprise two theoretical constructs. So even if different theoretical constructs have different features, that wouldn't mean that physical objects couldn't also be theoretical constructs.

This answer choice attempts to undermine a premise in the argument. Although physicists have suggested that energy is a theoretical construct, that suggestion is used a premise in this argument. On Errors in Reasoning questions, we need to accept those premises as true. The titutlar "error" is always a problem in the inference made between the premise and the conclusion — not a problem with the premise itself. Any answer choice that attempts to cast doubt on a premise — such as this one — is wrong. Moreover, this answer choice is off-target in its attempt to weaken a premise. The premise says that "many prominent physicists" have suggested that energy is a theoretical construct. However, this answer choice refers to a suggestion made by "a physicist." Even looking past the undermining-a-premise issue, there's a meaningful difference between a suggestion made by many prominent physicists and a suggestion made by one physicist. So this answer choice also misdescribes the premise in the argument and is wrong for that reason as well.