Yeah, there's a confusion here of formal conditional logic and causal logic/argumentation.

In causal, we are evaluating for strength of hypotheses rather than validity.

It's subtle but different.

The conclusion is the hypothesis - chemical spill caused the dolphins to die.

Before this, we have premises and proximal phenomena.

The main difference here is we are not determining if a conclusion is valid or invalid like in formal conditional logic. We are evaluating how strong or week a conclusion is based off of the causes/phenomena and the strength of alternate hypothesis.

You can't get some B's are C's from all As are Bs and all As are Cs. Where do Bs come in?

Let's see what an expert says, but I don't think that this is valid. "Most" does infer "some", but I don't think you can just deduce, from "most" a "some" statement.

Yes, this is possible.

It's an incredibly strong claim to say "ALL" that is not supported by the stimulus. We know they are likely investing "some resources" but there's nothing that tells us how much. We can infer that at least 1 resource was invested in and if that were the case, C would also be true.

I get the feeling the LSAT is going to have answer choices that make unreasonable claims like "All" and if we aren't paying attention, we will glance over it because the beginning of the answer choice looks pretty good.

Some can include all BUT MUST INCLUDE at least one. So it's not a given that "some" will always include "all" and we will likely have to rely on explicit or implicit indicators with context to figure out what the author is saying. This is annoying because we don't have conversations where we use "some" and "some" could include all. We would say all.

This is the LSAT being the LSAT.

Thank you, all!

I negated the wrong sufficient in 4 to make the lawgic more coherent. What a silly mistake.

You're most welcome! I want to send you another awesome resource I found that's helping me with questions. I don't know how to reach out to ya though.

I didn’t but the further you go, the easier this feels. Promise!

For question 5, could the domain also be an organization whose primary purpose is the promotion of health?

From there, the logic follows that - necessary ---> provided

Although, that's not what the sentence tells us now that I type that out. The sentence tells us that what's necessary SHOULD BE provided. CRAP!

provided ---> necessary?

Could something be provided but it wasn't necessary?

I was with you initially. I thought this, too. Let's take a look:

All New York City residents living in buildings with more than ten units have an inalienable right to keep a pet if that animal has been kept openly and notoriously for three months or more.

Let's break it down using the same symbols the instructor uses:

OpNo and 3+Ms --> NYC and 10+ and R

So if someone has an animal that has been kept open and notoriously for 3 or more months, then they are a New York City resident living in a building with more than ten units and have an alienable right to keep a pet.

It doesn't follow that someone who has an animal kept open and notoriously for 3 or more months must be a resident of New York City in a building with 10 or more units and has an alienable right to keep their pet. Can someone have a pet outside of New York City in a building with less units?

I'm just explaining this to help see the flaw in my own thinking because I was in the same boat as you.

Think about putting someone in the example of the logic you laid out.

The way you set up your sufficient condition suggests that someone has to be 21 and be older than 21 to be able to legally buy alcohol in the US.

Think through this: can an individual be 21 and older than 21 at the same time? Again, your lawgic suggests that BOTH have to be true in order to get our necessary condition.

Either someone has to be 21 or older than 21 to be able to legally purchase alcohol, not both.

Darn!

I almost had question 2 until it came to chaining. "He cannot kill both Arya and Sansa."

I saw a conditional statement but the statement wasn't conditional. "If he does not kill Arya, then he will kill Sansa" .

What it's basically saying is: /(A ^ S)

1. Both can be killed

2. One or the other can be killed

It's a valid argument based on the premises and the conclusion.

The premises are faulty however but you weren't asking for feedback there.

If you're looking for the contrapositive to your argument. It's basically taking an "if then" statement and flipping it, adding "not".

In your first it's if I leave for work after 8, then I will be late.

8 --> L where 8 symbolizes "If I leave for work after 8" and the arrow symbolizes "then" and L symbolizes "I will be late"

/L --> /8 is the contrapositive.

If I'm not late, then I did not leave after 8. It could be true that you left at or before 8.

I got the answer right initially and then my blind review took me to 'A'.

Would be really helpful to get why this isn't the correct answer in another way.

Because the argument doesn't state anywhere corporations which do not use posters, then we shouldn't bring this in to criticize the argument, correct?

So nice to get a tricky one right. The last one. What helped me...seeing "It was revered and considered invaluable to the people" prompted me to ask "why should I believe that" to which there was no point or premise.

I struggled with two. Looked at the words concluded and assumed that was the conclusion and it is A conclusion but not a conclusion by the author.

Still a conclusion. I don't even know if Michelangelo is in the Sistine Chapel but weather the assumption is strong or weak, the conclusion is still there supported by the premise.

Where can I practice more questions like this to get to mastery?

I got lucky getting the answer right. I tend to get tripped up on what "may be true" instead of what "must be true" in logical reasoning.