#4 - Dental researcher: Filling a cavity in a tooth is not a

[voodoochild]

Question :

[Question Removed by Admin -- LSAT questions cannot be posted per LSAC question disclosure rules. Just referencing the PrepTest number, Section, and Question Number as you did in the post title gives us all the info we need! ]

I was approaching this argument with any eye of "conditional logic". HEre's what I did"


Conclusion - Dentists should not fill a cavity unless the nerves inside the tooth are in imminent danger from that cavity.

OR (only if to if conversion)

If nerves inside the tooth are not in danger then doctor shouldn't fill the cavity

OR (contrapositive)

If doctor fills the cavity then the nerves inside the tooth are in danger (sounds funny!)

Premise 1 - Cavities are harmful only if the decay reaches the nerves inside the tooth OR (contrapositive)

Premise 1 - If Cavities are harmful then the decay reaches the nerves inside the tooth.

Premise 2 - Many times, if cavities are left untreated, then they never damage nerves.


I was completely lost at this point. I couldn't figure out assumptions using above work.

I could *logically* think of an assumption that the doctors will be able to predict imminent danger to the nerves, looking at cavities.

I was able to rule out, B,D and E answer choices. I see why C could be correct. But I am not able to rule out A.

CAn you please help me? Appreciate your help....


Thanks
Voodoo

[Steve Stein]

Hi Voodoochild,

The first thing to recognize here is that this is not an Assumption question, so you don't necessarily need to look for assumptions required by the argument.

To begin, what is the basic argument?

Cavities only do damage when they reach the nerve (which doesn't always happen), but filling cavities always does some damage.

Conclusion: So, filling should not be done unless it's a case of imminent danger.

The question that follows asks for the principle that "most justifies" the researcher's reasoning. This just means that the right answer choice will provide a principle that strengthens the argument from the stimulus, and only answer choice (C) provides a principle that would lead the dental researcher to draw the conclusion discussed above.

Please let me know whether that clears this one up--thanks!

~Steve

[voodoochild]

Thanks for the reply, Steve. However, your post completely ignores my questions, analysis and everything I wrote. Can you please help me with my reasoning? I am approaching this question with a critical eye of conditional logic. I know that many people would vote against it, but it doesn't hurt to solve the same problem using different methods.

Also, to your point about Assumption question, your book clearly says that it never hurts to identify Assumptions in the problems. After all, all LSAT arguments have some assumptions. No matter what.

Appreciate any response I can get.

Awaiting your detailed response.

[Dave Killoran]

Hi Voodoo,

I don't think Steve ignored your message . What he did was simplify the stimulus--which I think you may have been overthinking just a small bit. When we see someone going down the wrong pathway, or getting confused, often times the best approach is to say, "this is where you should really be going." I think that is what he was trying to do there. So, with that said, let's look at it more closely!

First, you note that "I was approaching this argument with any eye of 'conditional logic.' " As a general rule, keep in mind that your job is to recognize the reasoning that is present, not to force an interpretation onto the stimulus. In this sense you are like an air traffic controller: if it's there, you track it, but if it's not then you don't worry about it. Is conditional reasoning present here? Yes. Does that mean that it can all be connected together easily to solve the argument? No. The mere presence of conditionality does not mean that the whole problem then becomes primarily conditional and is the linchpin of the argument (this point alone is one we could discuss at length). It's up to you to determine how important it is, and how much attention to pay to it (including whether to diagram it or not, because in many instances conditionality can be present that doesn't need to be diagrammed).

Steve provided an excellent simplification of the stimulus, but in deference to your request for a deeper analysis of your reasoning, I'll add some points about the analysis you provided.

The breakdown you made of the stimulus wasn't entirely clear to me, but I think that is because your contrapositive of your premise 1 is simply a restatement of the premise, not the contrapositive. Also, keep in mind that once you have a conditional statement drawn out, you don't then need to formally write out the contrapositive--you can simply know it is there until you decide to join some of the statements together.

Moving on, making a breakdown similar to yours, I'd get:

• Premise 1: This is actually the first sentence, which indicates that filling in a tooth always causes harm. If you diagrammed it (and I wouldn't), it would appear as: Fill in tooth harm.
  
  Premise 2: Cavity harmful decay reaches nerves
  
  Premise 3: Untreated cavities (many) decay reaches nerve
  
  Conclusion: Fill cavity decay almost reaching nerve.

That actually is pretty similar to what you had, so your understanding of each sentence wasn't where you ran into trouble (that's actually very good news--from a component standpoint you were clear about what was occurring). But, at this juncture, you noted that, "I was completely lost at this point. I couldn't figure out assumptions using above work." Your comments here threw me off too, because this is a Strengthen-Principle question, not an Assumption question. While there's nothing harmful in identifying assumptions, and I mentally note the ones I see as I read, I don't spend a lot of time in looking at them and trying to figure out every one. Why? Because there are usually too many present, and really spending time thinking about many different assumptions usually is time lost. So, based on what you said in your post, I would have made the same point Steve did. Fortunately, because of what this question is, the great thing is that the principle they want is among the five answers, so you really don't have to be too worried if you feel like the assumption isn't jumping out at you. The right approach is to consider what might be there, but if it isn't clear, then move on. Focus on trying to make sure you understand the gist of what is being said.

That aside, the question is, why were you lost at that point? I think it's probably because you had all this conditionality flying around, and you wanted to have it link up smoothly, with just a nice gap missing that you could look for in the answers. Yes, we can easily link premise 2 and 3 using a contrapositive of one of the two premises, but still, that won't provide a perfect solution to producing the conclusion. That's why Steve simplified the reasoning down to:

• Cavities only do damage when they reach the nerve (which doesn't always happen), but filling cavities always does some damage.
  
  Conclusion: So, filling should not be done unless it's a case of imminent danger.

That reduces the argument to its essence: what's the harm level here, and how does that affect what we do? Given that the conclusion said not to fill cavities (which we know causes harm) unless harm is imminent, we then need an answer that pushes us in that direction.

In the answers, there's a lot of interesting things going on. For example, the whole stimulus is about teeth, yet only answers (A) and (B) deal with dentists. That actually makes me suspicious of them since this is a principle question. Putting "dentists/teeth" into (A) and (B) will actually draw some students towards them regardless of what those answers say (since it is the same as the topic in the stimulus), even though a principle by definition is broad and doesn't need to directly address the stimulus topic. Regardless, you efficiently eliminated three wrong answers and had it down to (A) and (C), so let's look at those (because we all know how annoying it is to get it down to 2 answers and not be able to decide between them!):

• Answer choice (A): This answer goes too far--"perform any procedure likely to be beneficial in the long term"--and that bothers me. But, this answer also deals with benefits vs harm, which is different from the way the stimulus uses no imminent harm vs harm.
  
  Answer choice (C): Note how this answer addresses the harm issue perfectly.

Please let me know if that helps. Thanks!

[voodoochild]

Thanks for detailed response, Dave. One thing I like about your book is that it teaches us to develop a habit to identify assumptions in first place because there is always a greater probability that the correct answer would either weaken or strengthen the assumption. Can you please help me to pin point some assumptions made in this argument?

Here's what I could think of : Doctors have an ability to identify those cavities that can lead to imminent danger..

Thoughts?

Appreciate your reply.

[Dave Killoran]

Yes, that's definitely an assumption that's in there. There is also the typical series of assumptions that relate to the "dental researcher" believing that he or she has it correct, and that all the statements are valid. Inside individual statements there are further assumptions such as that other aspects of cavities aside from decay aren't harmful. And then there broader systemic assumptions like the one you identified, or one such as that filling the cavity won't cause more harm than the imminent nerve damage.

Please let me know if that helps. Thanks!

[Sherry001]

Hello ;
I was able to choose the right answer through process of elimination but I really don't understand how it's a good match for the stimulus. I saw the right answer as a mistaken reversal /negation.

Question type: principle
1- filling a cavity damages some healthy parts of tooth .
2- if left untreated never progresses to a harmful situation.
C: dentists should fill cavity -> the nerves inside the tooth are in imminent danger


C) a condition that is only potentially harmful should not be treated using a method that is definitely harmful .( negated due to unless ) Should not be treated -> potentially harmful


Thanks so much for your help!
Sherry

[Laura Carrier]

Hi Sherry,

Your analysis is a good one, but I would like to tweak it a little, in a way that I think will clear up your question:

P1: Filling a cavity is always (inevitably) harmful, giving us a conditional relationship:

Fill cavity harmful

P2: The second sentence tells us that cavities can basically go in two directions—either harmful or not harmful—by essentially giving us a second conditional rule and its contrapositive: Cavities are harmful only if the damage reaches the nerve (CH DRN); but many cavities never reach this point and are therefore not harmful (Not DRN Not CH). So we could say

Cavity decay will not reach nerve

Cavity harmful decay reaches nerve (and its contrapositive: Decay will not reach nerve cavity not harmful)

And we can chain these together to know this:

Cavity decay will not reach nerve cavity not harmful

Since cavities in general might be of either type, and we wouldn’t know that any particular cavity was harmful unless we found out that it would satisfy the necessary condition of decay reaching the nerve, cavities as a group could be classified as only potentially harmful.

I agree with you that the conclusion looks like this:

Fill cavity (by definition, harmful) cavity is imminently harmful

Since this is a Strengthen—Principle question, you need to find an answer choice that provides a general rule that supports the reasoning in the stimulus, which draws a distinction between the two possible types of cavities and whether they should be treated by filling. Logically, the argument in the stimulus will follow from (or be helped by) the overarching principle in the answer choice, rather than the other way around. So the test of the principle in (C) is that, if it is true, it needs to make it more likely that the conclusion in the stimulus is correct.

If you want to interpret (C) conditionally, I would put it this way:

If a condition is only potentially harmful (such as a cavity that may not reach the nerve), then it should not be treated using a method that is definitely harmful (such as filling).

That would allow us to create a diagram that applies the principle to the facts of the stimulus as follows:

Cavity that has not yet reached the nerve (only potentially harmful) do not fill (definitely harmful)

Interpreted this way, it is more or less the contrapositive of the conclusion in the stimulus, and not a mistaken reversal or negation—though you are right to be vigilant in looking out for them everywhere you see conditional reasoning!

I hope this helps to clarify a tricky question.
Laura