Ooo the british english version of words are a fun distraction.

TL;DR, Some Tips:

"MOST"/"SOME" before "ALL", is a Valid call ; "ALL" before "MOST"/"SOME, is Invalid and hurts my tum.

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I went through the Review of Valid Formal Arguments in the last section and this Review of Invalid Formal Arguments and grouped concepts a bit differently than 7Sage. It's easier for me to understand opposite/competing rules by placing them side-by-side rather than trying to learn valid arguments in one go and invalid arguments in another go. I hope this helps others! Writing this all out reinforced the concepts for me.

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For all of these, I used the following ideas to better follow 7S's A→B→C set of examples:

A = Apes

B = Brave

C = Cool

x = Xander, an Ape

y= Yara, a human

xxxxxx GROUP 1 VALID ARGUMENTS xxxxxx

The Conditional Argument

A → B

(x)A

----therefore----

(x)B

All apes are Brave. Xander is an ape. Xander is brave. VALID.

The Contrapositive Argument

A → B [CONTRAPOSITIVE: /B → /A]

(y)/B

----therefore----

(y)/A

All apes are brave. Yara is not Brave. Yara is not an ape. VALID.

xxxxxx GROUP 1 INVALID ARGUMENTS xxxxxx

Confusing Sufficiency for Necessity

A → B

----therefore----

B → A

All apes are brave. All brave things are apes. INVALID. Some brave things could be non-apes, like human people studying for the LSAT.

Denying the Sufficient Condition

A → B

/A

----therefore----

/B

All apes are brave. If you're not an ape, you're not brave. INVALID. As in the other invalid argument form, we could point to non-apes that are brave, like you, future test-taker!

Affirming the Necessary Condition

A → B

B

----therefore----

A

All apes are brave. If you're brave, you're an ape. INVALID. Just because you have the necessary condition of being brave does not affirm that you have the sufficient condition of being an ape. Again, what if the brave thing is you, a human?

I suspect that was the easier part of these lessons for most of us to track. Moving on to the part I had to review three times...

xxxxxx GROUP 2a VALID vs INVALID ARGUMENTS xxxxxx

VALID re "MOST"

Conditional Chaining [Remember this is a chain of "all" statements, just helpful to see it against the various "most" and "some" valid/invalid arguments.}

A → B → C

----therefore----

A → C

All apes are brave and all brave things are cool, therefore all apes are cool. VALID.

Most Before All

A —m→ B → C

----therefore----

A —m→ C

Most apes are Brave. All brave things are cool. Therefore, most apes are cool. VALID.

Two Mosts

A —m→ B

A —m→ C

----therefore----

B ←s→ C

Most apes are brave. Most apes are cool. Some brave things are also cool. VALID.

INVALID re "MOST"

Most Statements are Not Reversible

A —m→ B

----therefore----

B —m→ A

Most apes are brave. Most brave things are apes. INVALID. What if there are billions of brave people, but only a few thousand brave apes?

All Before Most

A → B —m→ C

----therefore----

A ←s→ C

All apes are brave and most brave things are cool. Therefore some apes are cool. INVALID. Imagine we collect one billion cool things: tech equipment, scientific discoveries, Olympic medalists, yo-yos, and even a bunch of cool animals. Is it true that at least one of those cool things MUST be an ape? No, not based on this information alone. It COULD be true but it isn't a MUST be true. And "SOME" requires AT LEAST ONE.

Most Before Most

A —m→ B —m→ C

----therefore----

A ←s→ C

Most apes are brave and most brave things are cool, therefore some apes are cool. INVALID. I think 7S's explanation of why these are all similarly flawed is sound, so I wont repeat myself this is already soooo long I'm sorry.

xxxxxx GROUP 2b VALID vs INVALID ARGUMENTS xxxxxx

VALID re "SOME"

Conditional Chaining [Remember this is a chain of "all" statements, just helpful to see it against the various "most" and "some" valid/invalid arguments.}

A → B → C

----therefore----

A → C

All apes are brave and all brave things are cool, therefore all apes are cool. VALID.

Some Before All

A ←s→ B → C

----therefore----

A ←s→ C

Some apes are brave. All brave things are cool. So, some apes are cool and also some cool things are apes. VALID. There are 100 apes, they're all brave and that makes them all cool. That means that some (more than some, all, actually) apes are indeed cool but also in the world of total cool things, the apes have to be included.

INVALID re "SOME"

All Before Some

A → B ←s→ C

----therefore----

A ←s→ C

All apes are brave. Some brave things are cool. Therefore, some apes are cool. INVALID. Sadly if we were creating an intersection of brave things and cool things, we know the apes would be in the "brave things" circle, but there's no rule here that implies those brave apes intersect with the section of "cool things." Only SOME brave things are cool. Maybe it's just yo-yos and Olympic medalists and nothing else.

Some Before Some

A ←s→ B ←s→ C

----therefore----

A ←s→ C

Some apes are brave. Some brave things are cool. Therefore, some apes are cool. INVALID. 2 apes are brave. 13 things are cool, they're all yo-yos. No apes, in this situation, are cool, it's not enough to make an inference with this information.

If these last several lessons are ever updated, it would be so helpful if you could replace the "A"s and "B"s in the Lawgic write-ups with the actual example being used (ie Harry Potter friends/wizards or Jedi/Force, etc.). It would make following along and comparing our own work much easier.

Not yet, but I checked the website to make sure I wasn't missing anything. Looks like we should get sign up links around 10 days out.

https://www.lsac.org/update-coronavirus-and-lsat/lsat-flex

"The February LSAT-Flex.... will open the scheduling sign-up process about 10 days before the first day of testing in February. We will provide more information and instructions to test takers prior to that time."

I'm curious to know if anyone struggled with the interpretation in some of the answer choices that because the population is on an island therefore, "space is limited?" Even thought the "space is limited" answer choices are are wrong answers, I still spent too much time trying to understand that wording.

After getting this wrong twice and not being sure I understood how JY got to the answer choice, I decided to clean up my scribbles and draw this out to share. I think this might help other people like me who were stuck on the "Not Work of Art" = "Non-artistic" appeal to answer (D). Fair warning I haven't gotten to the logic part of the coursework so my mapping here might be amateur!

P = WA + (Some) MCL

N = WA + (Not Usually) MCL

S = WA + (Rarely) MCL

L = WA + (Some) MCL

- I was able to eliminate (A) because the passage did not say these are the only types of art.

- Eliminated (B) because I have no idea what blank verse it and fell outside of the scope of the passage.

C-E were hard.

(C) While a novel does not usually use MCL, in this case we're being told the novel did (meter and rhyme). So we now know for this Novel:

N = WA + MCL and

P = WA + MCL ---> (therefore)

N = P

(D - my original choice) This says that

L = WA = P; but we know

P = WA + (Some) MCL. How can

L = P when P requires something to be a work of art?

(E) The passage and answer choice appear to be trying to confuse us by mentioning the Musical Characteristic of Sound (which is required of a symphony) and the Musical Characteristic of Language (which is rarely part of a symphony). I didn't originally catch or map this (MCS vs MCL) which is why I spent so much time before being able to eliminate.