Yay! Congrats

I am a bit confused about #5 choices D. I understand why A is correct, but I feel like at least D could also be correct. I think the language "capable" is throwing me off.

I think I understand why E is wrong because we know nothing about the vocal expressions of animal besides that they can vocally express feelings and not objects.

Could someone provide an explanation for why answer choice D is wrong?

I'm just summarizing this here for my own notes:

For the answer to be correct in a necessary assumption question, the assumption would be required by an argument to validate it. The negation technique essentially just turns the answer choice into the opposite, and if that weakens the argument, that answer choice is likely to be correct.

I feel pretty confident when answering sufficient assumption questions, but I just don't always feel like I understand what sufficient assumption questions are asking. I understanding when to recognize it, but I feel like I constantly have to remind myself that the answer is enough to make the argument valid, not required. When you are going through the questions, I feel not confident in myself when answering even though I find myself being correct because I feel as though I don't have a grasp on what sufficient assumption questions are.

For Q3, wouldn't the premise of the argument be considered always true, since it's a premise? What would make it be considered an assumption?

@arat Effect, but I think you could think of it as either.

So when I answered this question, I immediately skipped over A as not having any effect on the correlation. I moved quickly from B as a weakening effect. I moved through the rest of the answers as not being correct either, which obviously confused me. I still came back to A because I could tell it was worded in a way to trip me up and I didn't quite understand it. I still don't understand it to be honest. I think I forgot to consider the assumption when evaluating the answer. I think it would be helpful to write it down or repeat the assumption that iron causes Parkinson's, but I also struggled to let go of my own concept of genetic predisposition. It's still not entirely connecting, I understand the explanation, but it just does not feel right.

@annngooyen So the contrapositive is almost like the inverted opposite of a sufficient-necessary relationship. So for example,

If A --> B, the contrapositive would be:

If XB -->XA

So, kind of like your statement. It just means that if the necessary condition is not true, then the sufficient condition is also not true.

For Q2 in the first practice quiz section, is there a strategy to come up with the answer prior to looking at the options? I did get the right answer when the choices were presented, but I'm not really seeing a way to get there without the choices presented. LMK if that makes sense.

I got the ship one wrong on level four (I think its the first question for level four, but I don't know if everyone gets the same questions each time). I initially put that the second sentence was a premise, but doubted myself and labeled it as context. I understand now that context would not provide any support for the conclusion, and this sentence did, so it should be labeled as a premise.

Pretty much the same logic I applied to the practice question, but it definitely took me longer.

I spent almost three minutes on this question. I actually diagrammed which helped me answer the question prior to reviewing the options. First, I highlighted important key words like "most" and "every." I almost missed the "lower than" phrase which would have screwed me up in this answer, but I re-read to make sure I didn't miss anything important and then diagrammed the question.

Basically my diagram looked like the below:

Most students ---> Every class

Lower than B- ---> Missed greater than or equal to one class

Therefore:

B- or higher ----> They went to every class

I didn't include anything after this diagram, but after reviewing it I would probably add this:

Most students ---> B- or higher (which would quite literally lead me to the right answer)

LMK if you have anything to add.