Q22 - Detective: Laser-printer drums

[LSAT-Chang]

Wow, can someone please go over this problem for me? I had no clue what the argument was talking about in regards to "nicks" and "drums".. The conclusion is that we can reliably trace a suspicious laser-printed document to the precise printer on which it was produced by matching a blemish on a page with a nick on a drum (have no clue what this means). So, basically since it is a weaken question, I tried to at least "guess" at something that could make it NOT possible to trace it to the precise printer or such -- so I chose (E). I was debating between A, C, E, but just went with E since I ran out of time. Now that I look at it, I still have no clue what this problem is talking about. Please please help!! I've never ran into a problem like this where I didn't know the "meaning" of a stimulus this question is really bugging meeeee!

[timmydoeslsat]

I did not know what exactly a laser printer drum was, but it was not needed!

A nick is like a small puncture or a scratch. Something that is of minor damage.

This stimulus can be seen as this:

Nick in a drum ---> Blemish of similar dimensions in print out paper


So we can RELIABLY use that print out paper to hunt for the exact printer that used, which will be done by matching the dimensions of that print out paper.

The problem I immediately thought of when I read this stimulus was..."What if there are many printers out there with the same type of nick? How then could it be reliable?"

That is what answer choice C states.

Think about it this way changsoyeon.

Let's involve you directly in this situation.

You are the police detective.

You are trying to put the bad guys away. You figure out this awesome new revelation that any nick in laser printer drums will produce the exact dimension of that nick onto the printed paper it produces.

You then conclude, "We can reliably trace a document to the exact printer it was produced by."

Is that necessarily the case? What if it were the case that the manufacturing plant that produced these laser printer drums manufactured 100 straight drums with exactly the same nicks (size, location, etc) but they were sent out anyway for retail purchase.

That means that we now have a 1 in 100 chance of tracing that print out to the exact one.

Please tell me if you would like to go over this more.

[LSAT-Chang]

This is definitely one of those typical arguments that conclude something for sure from insufficient evidence! I was trapped by all the "drums" and "nicks" that I wasn't familiar with and so ended up feeling shaky about it -- but anyways, thanks for the GREAT and fast reply to my post!! I really appreciate it! This question was stuck in my head since 10am this morning I solved it. Thanks so much!!

[charmayne.palomba]

PT46, S2, Q22 (Weaken)

(C) is correct.

Let’s start by finding the conclusion: that we can reliably trace a laser-printed document to the precise printer it was printed on. How do we know that? Because any nick in a drum will produce a matching mark on each page produced by that printer.

So here’s our core:

nick on laser printer drum produces matching mark on each page

-->

we can trace a marked document the document to the exact printer it came from

In weaken questions, the correct answer can seem to come out of left field, and could capitalize on a gap in many ways. What if the person who printed the document in question wanted to frame his unsuspecting sidekick, and switched the damaged drum to another printer? What if he threw it out altogether? Or made a matching nick on another drum to throw detectives off his scent? The important thing to remember with weaken questions is to remain flexible. Spend a bit of time brainstorming possible ways to weaken the argument, but don’t waste too much time. Rather, move onto the answer choices with the gap in hand and an open mind.

(A) is irrelevant to the core. The author is arguing that by matching the nick on the paper to that on a drum, the exact printer can be pinpointed. He never claims that this will lead us straight to the person who printed the document. (In fact, criminal is slipped into this answer choice to distract us; we might fall for this answer with a thought process that goes something like, "ah, see, the nick matching doesn’t lead us straight to the bad guy, because maybe he didn’t use his own printer!" But the author’s claim is that the nick leads us to a printer, not a person.)

(B) The author only claims that we can use the matching process to reliably trace the document to a printer; he never says it’s an easy process. If anything, we might argue that it weakens the conclusion, but that’s not our job. This answer choice doesn’t address the relationship between the premises and conclusion.

(D) The argument is about matching a mark on a document to a nick on a drum. The argument is only addressing situations in which there is a visible mark on the paper to match, so those are the only scenarios we care about. While this choice might seem tempting, it’s actually out of scope. Furthermore, who cares if the blemishes are sometimes covered?

(E) This is also out of scope. We only care about documents with marks produced by nicks on laser printers; the argument is about the feasibility of matching those marks to the drums that produced them.

Only (C) weakens the argument. The author claims that matching the marks on the document will lead us to the precise printer (only one!) on which it was produced. If the manufacturing process produces more than one drum with that same nick, the author’s argument falls apart. It only works if we’re guaranteed that each nick on a laser printer drum is completely unique.

[KakaJaja]

Hey, I have a question about C.

As the argument said, laser-printer drums are easily damaged. With C, though it is true that all printers have the same blemishes during the manufacturing process, every printer still can have unique blemishes due to daily use. So I don't think C is strong enough?

Thanks!

[wj097]

Hey, I have a question about C.

As the argument said, laser-printer drums are easily damaged. With C, though it is true that all printers have the same blemishes during the manufacturing process, every printer still can have unique blemishes due to daily use. So I don't think C is strong enough?

Thanks!

If we take a closer look at the argument once more, it is saying if we can just match the blemish then reliably trace. So while we CAN reliably trace for the case you mentioned, there are many other cases where you CANNOT. And (C) opens up for that possibility. Simply think about a case where the only blemish you have on a document is the once caused from bad manufacturing process...hope you see the difference.

[Antnat]

Regarding answer choice (D), how can we ascertain that the stimulus is only talking about pages with visible marks on the paper? Couldn't it be that we are talking about all pieces of papers with blemishes, regardless of whether or not the blemishes are concealed by ink printed over them?
(I understand that D is too weak because it says "often", but I am curious about what the actual subject of this argument. )

[JerryB218]

What confused me on this question are the first three words "laser-printer drums" that I misread as "laser-printed drums" - which completely throws the context into a way different bunny hole. I mistakenly thought the writers were speaking of drums (instruments) that were laser-printed! Take-away: one must always read *every word carefully*.

[jons824]

The thing is that we need to know how the drums and all the details regarding the laser printer drums. Implementing the printing on the laser printer can be done by the user if the user knows the process very well.

[KenB949]

you right jone!!!

[ShariS937]

I see how D gives us a "sometimes" scenario, when the stimulus gives us a "reliably every time" scenario.

Why is "sometimes" not the weakest weakener to "reliable" though? If the idea is that the detective can "reliably" trace a doc to a precise printer then, if they can only do it "sometimes," that precludes "reliably."

Answer C has "often," which is pretty similar to "sometimes..." But, fine, there are two answers that make the not-always move, and I need to pick one.

In choosing between C and D, though, how do I know to limit the time when damage could occur to a time before the print drum reached the printer? Manufacturing could turn out a million drums with the same flaw, but I could still have 1 "easily damaged" drum with a unique flaw - say I dropped it, or threw it at a wall to see if it would stick?

The idea that ink could defeat the drum flaw, whether it was damaged during manufacturing or after, seems like the bigger no way. Why is it not?

[Misti Duvall]

For Weaken questions, the easiest way to analyze them is to read each answer and think "does this statement make the conclusion less likely." If yes, then keep, and on second pass pick the answer that weakens the most. And remember that the answer does not have to destroy the conclusion, just make it a little less likely.

I think the biggest and easiest difference between (C) and (D) is the "often" v "sometimes." Both answers give us problems with the conclusion that would diminish the reliability of matching a blemish on a page with a nick on a drum. So if we have two options and one sometimes causes a problem and the other often causes a problem, the one that often causes a problem is the bigger issue. And therefore the answer that most weakens.