Hey man. Yeah, I sympathize. Work has interfered with my prep so much that I'm using a fat chunk of PTO to prep for this LSAT on Saturday. Every hour counts now. I stay focused by taking little breaks, for example by messing around on this forum between LGs. The biggest motivator, though, is putting on my future-me shoes and picturing the awful regret of choking on the test bc I wasted time. How nice it would be to hop in the time machine to the part where you waste hours/days/weeks you could have used to lock up those weak areas.

And snap! Dream come true.

Bottom line: Slow is fast.

Stress and panic will shut your brain down, HARD. I know this all too well because I have a job that frequently involves on-the-spot mental arithmetic, and there is a patent correlation between my stress level and my ability to perform those cognitive tasks. It has been an explicit concern of mine for years, esp. since my credibility depends on it.

So hear me when I tell you that rushing yourself will not work. The fastest, most accurate approach to analyzing problems is to calm down, put your worries aside, and focus on the problem. This will feel too slow when you're in a rush, but remember 2 things: (i) trust the clock to tell you what's too slow, not your subjective sense and (ii) an RAF (ready, aim, fire) approach, if somewhat slower per shot, is more accurate and ultimately faster than taking multiple shots (frantically re-reading).

Re-reading a problem or, God forbid, an RC passage, is like re-packing an old muzzle-loader. It's such a loss of time when you botch the first attempt. It happens, but you have to keep it together and minimize those occurrences. Know when to skip, too.

Try to relax by taking comfort in the knowledge that you actually perform best when you're calm and confident.

Conditionals are more presentable in formal logic, but you can keep it casual in an appropriate setting.

https://media.giphy.com/media/lfoC8HjUQlQT6/giphy.gif

Sorry for not addressing your questions directly. I don't know who would be in a position - who would have the statistics - to answer those questions. I've seen ppl here recommend "at least 20 PTs," though it's important to leave some for future prep in case you choke on the first take.

I can only tell you my case. I plan to take in Feb (may not be able to for ID reasons). I put in a solid month of LG drills in Oct and then got swamped with work and had to take 2 weeks off (now) to prep full time. So my prep sucks compared to the ideal. Here's where I stand:

Diagnostic: 164

PTs: 15 (7 40s, 7 50s & PT69)

Max: 177

Past 3 average: 173

Test Goal: 175

Most of the improvement came from JYs LG videos and effective skipping.

My issue was 80% LG, so it's been easy to focus my energy on that. Your case may be different, but I'm impressed by your diagnostic bc I went -10 or -12 in my first LG section. I just sat there trying to ratiocinate it out like a doofus with no notion of a diagram.

Be careful about the scope. You showed a proof to this effect:

(A->B)->C

....

~C->A; ~C->~B

I gather that, in the discussion you alluded to, JY was simply showing hypothetical results for a situation where you start with that particular formula. For safety, I just want to point out that 'A->B->C' is ambiguous between '(A->B)->C' and 'A->(B->C)'. These are absolutely not the same thing.

Because ambiguity can lead to misinterpretation, it's important to avoid sentences like the following.

A & B -> C

C -> A & B

A & B or C

A or B -> C

These are just examples of sentences that mean different things depending on how you bracket them. The brackets set the scope of each truth function (and, or, not, ->), so these are called scope ambiguities.

Bonjer mone amy, jay parl fantsay avek un axon amerycan.

But really, I spoke decent French once upon a time. If you're struggling and need some pointers, IM me. Prelim advice would be to do 4 things: learn 20 verbs and 20 nouns every week, watch French movies, go talk to weirdos in French chat rooms and eke your way through a few articles from Le Monde.

Heads up, tons of perverts in French chats. Don't use a screen name that can in any way be interpreted in a feminine light. When I was a kid, I had pet turtles, so I used "tortue." Well, that's a noun of feminine gender in French. Big mistake.

On that note, I learned early how uncomfortable life might be for women. That was the Internet, but I think it just brought out the predatory appetites women sense in so many men all the time. Truly disturbing.

You have to change the "any" to "some" as well.

The original:

(All candidates)(~X->~Y)

Or "All candidates are such that if they're not pretty then they won't get elected."

Negated:

~(All candidates)(~X->~Y)

Drop the negation on the quantifier through to the sentence and change the quantifier:

(Some candidate)~(~X->~Y)

Or just

(Some candidate)(~X&Y)

Just remember "not all A are B" is the same as "some A are not B." Or, as I like to say, "not all" means "some not."

Good luck on the test mang.

what @ said

I'm with you @

The sentence says it's required. It's easy to get paranoid with LSAC constantly throwing verbal tricks at you, but sometimes you just gotta say "the sentence says x" and move on.

What I find tricky about this one is that the meaning of the written sentence is different from the typical meaning of an utterance of the same sentence. We often say "all you have to do is x," meaning "x alone is sufficient, nothing else is required." "You only have to donate $10 a month to feed a hungry child." Of course, you could also feed a hungry child by raising awareness through your blog or by genetically engineering a more robust crop.

--digression: objectivity

Tricky as LSAC may be, they have to play fair. It's no surprise that one of the very early RC passages was about Reader Response Theory, a thesis to the effect that literary meaning is largely subjective. That would present serious probs for LSAC, since they need their answer choices to be objective. Interesting to go back and read that passage with the test objectivity problem in mind.

---digression: logical form

Interestingly, you need modal resources to say what we normally mean by "all that is required...," interpreted in the usual way as "A is suff. for B and nothing else is nec."

In classical logic, you use the material conditional ('->') (MC). That's what you learn in the CC. It's not very close to natural language conditionals, though. You would normally be inclined to express the above sentence this way:

(A->B) & ~(B->C)

Where C is any proposition, including A. You would normally use propositional quantification to say that, but I'm afraid this is prob confusing enough already.

The prob is that ~(B->C), in classical logic, means that B is true and C is false. But we're just trying to say C isn't necessary, not that it's false. That's the issue with the MC. Look up paradoxes of material implication for more intriguing examples of the MC's shortcomings.

Those paradoxes motivated developments in modal logic of necessity. This language allows you to say e.g. that B doesn't necessarily imply C without asserting anything about the truth of B or C. So the right way to express the colloquial meaning of the utterance discussed above is this:

(A->B) & ~□(B->C)

Where C is any proposition.

I release you.

@ My dealer is Phil O. Sofia. Try some of this sh**:

http://fitelson.org/proseminar/barcan_marcus.pdf

@ that is a beautiful, glorious example.

If anyone's interested, the modal fallacy in No. 21 goes like this (BA=belief ascription):

BA(P),

P -> Q,

So BA(Q)

...ignoring the other fallacy in the problem. Again, sentences in modal contexts lose their normal logical properties. In classical (extensional) logic, you can e.g. infer B from A&B, but statements in modal (intensional) contexts lose their normal logical properties.

Of course, modal expressions have truth values and may feature unproblematically in wider extensional formulae. Here's a valid example:

BA(P) -> BA(Q),

~BA(Q),

So ~BA(P)

This is formally identical to-

P -> Q.

~Q,

So ~P

There's no interaction between modal and non-modal content there. But some modal constructions do allow operations within and between modes. Alethic modality (necessity/possibility, □/◊) is the big one. A valid example:

□(P -> Q),

◊P -> □P,

P,

So □Q

Here's an informal interpretation that might help illustrate.

Necessarily, if 12 is divisible by 6 then 12 is divisible by 3.

If it's even possible that 12 is divisible by 6 then it must be that 12 is divisible by 6.

As a matter of fact, 12 is divisible by 6.

So it must be that 12 is divisible by 3.

And, at long last, you see that words like "must," "can," "probably," "certainly," "surely," "doubtful" etc. can function as modal constructions and must be monitored (see what-a did there?).

By the way, a guy named Rudolf Carnap got the ball rolling on alethic modal logic in the 1940s by defining the necessity operator so that it was true always and only when applied to logical truths ("L-truth"). Example:

□{ [P & (P->Q)] -> Q}

I point that out bc "must" and "necessarily" often signify the logical conclusion of an argument, which is okay. Indeed, the whole idea of the necessity operator was to express the implication between premises (sufficient) and conclusion (necessary) in logical deduction, which is not the same as material implication ('->').

Anyway, I found AC (D) of No. 21 deeply interesting, as it raises an age-old question about quantifying in. Essentially this means talking about a variable inside a modal context from outside that context. It's a famous topic in the history of logic.

The typical example:

Necessarily, the number of planets is odd.

That's "the number of planets is odd" in an alethic modal context (necessity). We know the number of planets (incl. Pluto) is 9, but is the number of planets necessarily odd? Prob not. There might have been, say, 6 planets.

The problem comes with the way I refer to 9 in the modal context. To see this more clearly, notice it's true that "necessarily, Donald is Donald;" but it's false that "necessarily, the president is Donald," even though Donald is the president.

But if we rephrased the planet sentence thus:

About the number of planets (9), it's necessarily odd.

Now the way I'm referring to 9 is outside the scope of the modal operator, and the sentence is plainly true. It's a logical certainty that 9 is odd, however I refer to it.

Same situation in (D):

John believes that 4 is an even prime number.

This is a belief ascription. The modal construction "John believes that p" bars us from inferring anything from p. That is, we can't conclude from "John believes A is B" that "John believes something is B." He failed math, clearly. He might believe the first thing and not the second. As far as we're concerned, that just says "John believes *****." The words are referentially opaque, as they say.

But if we're allowed to quantify into the context "John believes..." from outside, we can rephrase:

About the number 4, John believes it is an even prime number.

And from that it's logically guaranteed that -

There is a number such that John believes it's an even prime number.

Quantifying in switches the statement from the de dicto version (whole sentence in the scope of the modal operator) to the de re version (object reference outside the modal context).

So when I see (D), I wonder Can I quantify in? Not relevant for No. 21, which deals with a straightforward de dicto fallacy, but I'm happy if my rambling has raised any interest in modality. It's clearly nice to understand from time to time.

Heh, yeah. Pretty cool guy. I'm curious how he was raised.

Logic is a language like English, just a lot more precise. That means it's generative. There's no limit to the length and variation of things you can say, and each logical expression semantically entails certain valid conclusions. Short of proof -theoretic axioms like "if A and B, then B," there can't be a finite list.

There is sort of a solution, though. If you limit the number of premises and the number of terms in each premise, you can get a long but finite list. In the Middle Ages, scholastic philosophers trying to build on Aristotle went about listing all the valid categorical syllogisms. They gave them weird names.

It's fun to check them out every now and then.

https://en.m.wikipedia.org/wiki/Syllogism

Nice. I was pretty relaxed about the wait at first, but then I looked at the calendar and thought "It's only the 11th?! U-g-h-h."

Btw it's Black History Month. People seem to forget. If nothing else, check out the new Roots or see the original if you haven't. Just one way to relax and get your mind off the wait.

Yep, you're normal...well normal in the LSAT world

Lol @

I wasn't expecting to be affected by it, but I admit the whole LSAT scene is quite an experience - and not one outsiders can really understand.

This a lot like the naturalistic fallacy (NF) (is/ought). Both are modal fallacies. The NF involves deontic modality and these knowledge problems involve epistemic modality. Knowledge assertions can usually be treated the same as belief ascriptions or any of the other propositional attitudes.

In a nutshell: modality.

@ I agree. That was a super easy 6-spot sequencing game in disguise.

Hey @. Yeah, I have to give the writers their due. They're crafty. Listen, thanks for hanging around and helping us out. Your voice on this forum definitely contributed to my preparation. There's nothing like the experience of someone who went through it and came out on top.

@

No, weird bubbling patterns are more likely intentional than unintentional, I think, so seeing that doesn't worry me. On that note, anyone else notice goofy BBB, AAA type stuff all up and down the experimental sections?

@ Dang it. I did better on the fake one. Thanks man.

Sorry you got flustered. It takes a lot to collect yourself in the middle of LG like that.

LG, LR, RC, LG, LR. I can't tell which one was experimental. Any way I can find out without breaking the rules? If they don't change the order, I guess it was the 2nd?

Cool thread. I would like to make a contribution by asking some questions.

Suppose I claim that all swans are white. I offer this evidence. Every non-white thing I saw in my garage yesterday was not a swan. Does that in any way support my claim?

Or how about this. I think all my friend's stock investments will fail this year because none of the investments he made last year that succeeded were stock investments. Does that support my claim?

Or this. I think my car is more likely to break down than my friend's car. His car is a Toyota, mine is a VW, and more than half of the cars that break down in my city are German cars.

The truth is that standard Confirmation Theory, the academic analysis of evidence, says all of these kinds of evidence actually do support those claims to some extent. Puzzling at first, yes, but nevertheless true.

It is abundantly clear to me that LSAC does not follow the literature on evidence. I've seen stuff like that all over LR in answer choices that are intended to be obviously wrong in weaken/strengthen problems. Luckily, they usually pale in comparison to the intended choices, but sometimes I get stuck asking myself whether I should think more about evidence or more about LSAC's methods when I'm doing a section.

That's what I find trickiest about it.

Lol @ I felt like you asked a poignant and challenging question, very much to the point. It made me feel like a bloviating asshole for throwing things out there and expecting them to be uncritically accepted.

Hey @

If you take correlation in the statistical sense of two factors having an improbable (assuming randomness) amount of covariance, then they are quite different. There would be absolutely no statistically significant relationship between A and B in a chaotic system, even though there are deterministic laws governing B based on A. It's that system itself that is chaotic. Even accounting for all other factors, there could be absolutely no statistical relationship there.

That's different from the second point, where the lack of a discernible correlation is simply due to ignorance of other influences.

Chaos Theory is often misinterpreted as being based on ignorance of all the factors, so to speak, which is way off base. It's a deep, deep discovery about the inscrutability of some non-linear systems. The implications for our ability to understand the natural world are profound.

But if you take correlation to mean just a non-random relationship (not just improbable), one that is to some extent determined, whether observed or unobserved, then you're right, causation does always imply correlation. But by that definition, it's hard to see how correlation doesn't imply causation, which in the leanest scientific sense just is such a deterministic regularity the world.

So as long as we're distinguishing the two, I would just point out the exception for chaotic systems.

Not really relevant for LR questions, though. Just pointing that out because CT is quite earth-shattering precisely because it undermines that assumption about the world.

On the LSAT, yes.

Philosophically, no. Actually, I remember an RC passage about discoveries in Chaos Theory that implied there may be some physical processes we'll never understand because they behave chaotically, meaning experimental results are so sensitive to initial conditions - perhaps arbitrarily so - as to be unrepeatable. In a nutshell, there could be a causal relationship between A and B without any discernible correlation.

A more mundane example, though not really a counterpoint, is that experimental or observational conditions aren't controlled enough to account for disruptive factors, which could conceal otherwise observable correlations between causally related factors. For example, we could do a study of smokers and non-smokers to show no correlation with heart disease by choosing an older sample of nonsmokers than smokers. But, as I said, that's not really a counterpoint, since in that case you choose just the "biased samples" flaw or whatever.

How you feel going in

https://s-media-cache-ak0.pinimg.com/originals/ca/cc/fb/caccfbc5c771bde940105f9bdb30e3e6.gif

How it could feel coming out

http://projectfandom.wpengine.com/wp-content/uploads/2015/04/Ragnar-hardcore-Vikings-3x8.gif