But if I say that not all dogs are friendly, can we infer, or can we deny, that no dogs are friendly? It doesn't half to be the case but its not outside the realm of possibility here.
All A are B. To negate this claim we must deny the relationship, not the existence of a set. The way we think about this relationship is the quality of being "all". To deny the relationship, we would say some As are not B.
All jackfruit is splendid. J->S
Negated: J <-s->/S meaning some jackfruits are not splendid.
There's a typo in this. In the 'lets review' section it says "in this instance, an 'all' relationship, you are trying deny that relationship." There is a 'to' missing- it should read "trying to deny that relationship."
So, in this lesson we're learning how to negate a relationship, but previously we were negating conditions/logic? I'm a bit confused on how to put into words the difference between
A->B
/B->/A
and this new process that goes:
A->B
AB
If the indicator word is "all", how do you know whether to take the negation of the sufficient condition or this new negation process for "some"? Or does it boil down to what the question stem asks? Thanks in advance for any help, I'm a bit too confused to explain what exactly is confusing me...
Couldn't we just say "not all dogs are friendly" in order to negate "all dogs are friendly"? Is there a difference between "not all dogs are friendly" and "some dogs are not friendly"?
#feedback HELP!!!. I don't get this at all. What we learned in previous lessons says that If A---B. How is that not any different then ALL A are B. A---B. its just so counter intuitive I don't get it. IF you say all dogs are friendly how is the negation not all dogs are friendly.All means all there is no room for other dogs..
#feedback It's not clear with how this lesson is written whether or not "It's not the case that all dogs are friendly" can include the possibility that "No dogs are friendly". Translating it into "some dogs are not friendly" would exclude "no dogs are friendly", since we learned earlier that "some" has a lower boundary of 1. However, from a common sense perspective, it seems to me that "it's not the case..." should include the possibility that "no dogs are friendly".
Can someone point out an LSAT question where this would appear
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106 comments
But if I say that not all dogs are friendly, can we infer, or can we deny, that no dogs are friendly? It doesn't half to be the case but its not outside the realm of possibility here.
Where would we use this idea of negating "all"? Like what question type on the lsat?
1. SOME DOGS ARE FRIENDLY
At least one dog is friendly
Not all dogs are not friendly
Negate: No dog is friendly
All dogs are not friendly.
2. ALL DOGS ARE FRIENDLY: 100% dogs->F
Negate: It’s not the case that all dogs are friendly.
Not all dogs are friendly: >100% dogs->F
Some dogs are not friendly
Arbys
Do not confuse this with the creation of contrapositives which are logically equivalent to the original statement.
All A are B. To negate this claim we must deny the relationship, not the existence of a set. The way we think about this relationship is the quality of being "all". To deny the relationship, we would say some As are not B.
All jackfruit is splendid. J->S
Negated: J <-s->/S meaning some jackfruits are not splendid.
All pens are black
P -> B
Negated: Some pen's are not black
P <-S-> /B
To negate all relationships we are saying "It' not the case that all pens are black".
What this does not mean is all pens -> /black. THIS IS A TRAP. All this negated statement means is that "Some pens are not black"
Can this be applicable to "any" and "every"?
Original: All A are B
Negated: Most A are not B ?
I'm confused on why it can't be "Not all A are B" instead of bringing some in it
I am going crazy. Why isn't the negation "if you are not friendly, then you must not be a dog" ?
How can not all mean some if some can mean all?
So looking it from point of view of sets and subsets we notice that
Original: D → F
implies that Dogs is a subset of Friendly.
Whereas negated...
Negated: /(D → F)
The Dogs set is intersecting with the Friendly set? and some dogs are outside the Friendly set intersection.
https://miro.com/app/board/uXjVJL9zNgA=/?share_link_id=597707785172
Would that be correct? If so how can we get more out of thinking in sets?
Is there a drill set or specific questions to practice with quantifiers? This is one area where I struggle a lot.
There's a typo in this. In the 'lets review' section it says "in this instance, an 'all' relationship, you are trying deny that relationship." There is a 'to' missing- it should read "trying to deny that relationship."
For a nessscary assumptipn is this similar?
So, in this lesson we're learning how to negate a relationship, but previously we were negating conditions/logic? I'm a bit confused on how to put into words the difference between
A->B
/B->/A
and this new process that goes:
A->B
AB
If the indicator word is "all", how do you know whether to take the negation of the sufficient condition or this new negation process for "some"? Or does it boil down to what the question stem asks? Thanks in advance for any help, I'm a bit too confused to explain what exactly is confusing me...
To negate:
All --> 99%
Most --> 49%
Some --> 0
None --> 1
#Feedback, can I accurately negate "all" using "some" without having to use the " It is not the case" preface statement.
Couldn't we just say "not all dogs are friendly" in order to negate "all dogs are friendly"? Is there a difference between "not all dogs are friendly" and "some dogs are not friendly"?
#feedback HELP!!!. I don't get this at all. What we learned in previous lessons says that If A---B. How is that not any different then ALL A are B. A---B. its just so counter intuitive I don't get it. IF you say all dogs are friendly how is the negation not all dogs are friendly.All means all there is no room for other dogs..
cats --> friendly
/friendly --> /cat
Is this the same as
it is not the case that all cats are friendly? meaning there is some cats that are not friendly?
I had a whole question typed out here, and then I drew it in the circle graph and it made sense! hahaha
#feedback It's not clear with how this lesson is written whether or not "It's not the case that all dogs are friendly" can include the possibility that "No dogs are friendly". Translating it into "some dogs are not friendly" would exclude "no dogs are friendly", since we learned earlier that "some" has a lower boundary of 1. However, from a common sense perspective, it seems to me that "it's not the case..." should include the possibility that "no dogs are friendly".
Can someone point out an LSAT question where this would appear