If so, can someone please explain why this form is invalid? Thanks in advance!
Is the explanation that '←S→' is implied within 'All' and we already know that 'all' cannot proceed '-M→' or ' ←S→'. If it does proceed either of those two quantifiers, the argument is invalid, is my basic understanding.
This lesson was helpful as it summarized exactly what I was doing wrong in previous drills, skill builders, etc. Yes, some of these flaws are implied, but something simply wasn’t clicking for me. I’m going to do a few drills now to make sure that I understand where I was going wrong. Overall, I feel a bit more confident in my understanding of the formal arguments.
I honestly don't think this lesson sucks at all. As DAVEMARINO said below, you need to have a strong grasp of the lessons on sets. I too was having problems recognizing formal logic flaws in drill and preptest questions until I went back and reviewed both of the sections on sets. One thing that significantly helped me was to write down each of the 8 formal logic flaws on a separate piece of paper (with their examples and Lawgic forms) and have this paper next to me as I drilled. Having the flaws in open view as I drilled helped to facilitate my pattern-recognition of these flaws whenever they appeared in questions. Eventually, you begin to recognize them instinctively. Above all, practice practice practice.
Y'all need to chill. They are working as fast as they can to update the lessons. I know it sucks but there is only but soo many hours in a day. Let's try to use the written format for now until they get it updated :)
This is not a good lesson at all. 7sage either you review this or you will be losing customers like myself. Instead of listing all the wrong parts you should list the correct ways. The titles are also very confusing. I've never seen someone summarizing the wrong things of something. Summarize what is correct so someone can remember the good parts.
Also, you have videos on grammar and not the MOST important things like this? This is where you should have videos, not useless grammar on nouns and verbs.
I've had 7sage for a few days now and all I can say is it's wasting my money and time.
If you didn't fully grasp the "Logic of Intersecting Sets" section, this "Formal Logic Flaws" section is useless. Though this last lesson is a nice summation.
Would be more helpful if it was formatted the same way as LIS, and had videos.
This section on flaws needs some serious work. Videos would help clarify things to a greater degree than these pitifully written explanations. I had to go to another site to get clarification.
#feedback I feel it would be helpful to also include what the valid form of the arguments are so that in the review we can have a quick way to reference a valid/invalid argument for example, and see how the test writers try and trick us.
I have a question regarding the all arrows. If A --> B and A --> C lead to B some C because the all arrows can be converted into most arrows (aka the valid form: Two Split Mosts), is there any conclusion we can draw from having two statements such as B --> A and C --> A? In other words, when it's no longer the same sufficient term with two necessary terms but instead two different sufficient terms with the same necessary term. Would we just combine the two statements so that it becomes B + C --> A?
If you switch to V1 and look for the section called "Invalid Argument Forms" they have some video lessons like this one: https://7sage.com/lesson/distinguish-valid-from-invalid-forms/
Does anyone know where I can find a video similar to this explanation? It is much easier for me to understand it with examples or if I hear someone explain it than it is to read
"MOST"/"SOME" before "ALL", is a Valid call ; "ALL" before "MOST"/"SOME, is Invalid and hurts my tum.
----------------
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.
-----------------
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.
The best is to to have an exhaustive list of valid inference rules. The fallacious arguments are simply those that don't operate strictly on those rules. The names you wanna give the fallacies are window dressing.
so basically statements that start with "all' are invalid ONLY IF the next sentence begins with "some", "most", etc? or is it that all statements that begin with "all" are invalid?
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61 comments
Is this below example an invalid argument?
A ←S→ B -M→ C
__________
A ←S→ C
If so, can someone please explain why this form is invalid? Thanks in advance!
Is the explanation that '←S→' is implied within 'All' and we already know that 'all' cannot proceed '-M→' or ' ←S→'. If it does proceed either of those two quantifiers, the argument is invalid, is my basic understanding.
I just don't understand how the grammar lesson had so many thorough explanations with videos but not this lesson... very disappointing
if you were my greatest enemy, i would screenshot these invalid arguments and send them to you and tell you that they're valid
This lesson was helpful as it summarized exactly what I was doing wrong in previous drills, skill builders, etc. Yes, some of these flaws are implied, but something simply wasn’t clicking for me. I’m going to do a few drills now to make sure that I understand where I was going wrong. Overall, I feel a bit more confident in my understanding of the formal arguments.
I honestly don't think this lesson sucks at all. As DAVEMARINO said below, you need to have a strong grasp of the lessons on sets. I too was having problems recognizing formal logic flaws in drill and preptest questions until I went back and reviewed both of the sections on sets. One thing that significantly helped me was to write down each of the 8 formal logic flaws on a separate piece of paper (with their examples and Lawgic forms) and have this paper next to me as I drilled. Having the flaws in open view as I drilled helped to facilitate my pattern-recognition of these flaws whenever they appeared in questions. Eventually, you begin to recognize them instinctively. Above all, practice practice practice.
Y'all need to chill. They are working as fast as they can to update the lessons. I know it sucks but there is only but soo many hours in a day. Let's try to use the written format for now until they get it updated :)
This is not a good lesson at all. 7sage either you review this or you will be losing customers like myself. Instead of listing all the wrong parts you should list the correct ways. The titles are also very confusing. I've never seen someone summarizing the wrong things of something. Summarize what is correct so someone can remember the good parts.
Also, you have videos on grammar and not the MOST important things like this? This is where you should have videos, not useless grammar on nouns and verbs.
I've had 7sage for a few days now and all I can say is it's wasting my money and time.
If you didn't fully grasp the "Logic of Intersecting Sets" section, this "Formal Logic Flaws" section is useless. Though this last lesson is a nice summation.
Would be more helpful if it was formatted the same way as LIS, and had videos.
This section on flaws needs some serious work. Videos would help clarify things to a greater degree than these pitifully written explanations. I had to go to another site to get clarification.
Confusing Sufficiency for Necessity
A → B
_
B → A
Denying the Sufficient Condition
A → B
/A
_
/B
Affirming the Necessary Condition
A → B
B
A
Most Statements are Not Reversible
A —m→ B
_
B —m→ A
All Before Most
A → B —m→ C
_
A ←s→ C
All Before Some
A → B ←s→ C
_
A ←s→ C
Most Before Most
A —m→ B —m→ C
A ←s→ C
Some Before Some
A ←s→ B ←s→ C
A ←s→ C
Does this resolve the example?
A and /B → C
/C→/A or B
#feedback I feel it would be helpful to also include what the valid form of the arguments are so that in the review we can have a quick way to reference a valid/invalid argument for example, and see how the test writers try and trick us.
I have a question regarding the all arrows. If A --> B and A --> C lead to B some C because the all arrows can be converted into most arrows (aka the valid form: Two Split Mosts), is there any conclusion we can draw from having two statements such as B --> A and C --> A? In other words, when it's no longer the same sufficient term with two necessary terms but instead two different sufficient terms with the same necessary term. Would we just combine the two statements so that it becomes B + C --> A?
#help
If you switch to V1 and look for the section called "Invalid Argument Forms" they have some video lessons like this one: https://7sage.com/lesson/distinguish-valid-from-invalid-forms/
I found it to be helpful!
A skill builder of this would be nice
Does anyone know where I can find a video similar to this explanation? It is much easier for me to understand it with examples or if I hear someone explain it than it is to read
TL;DR, Some Tips:
"MOST"/"SOME" before "ALL", is a Valid call ; "ALL" before "MOST"/"SOME, is Invalid and hurts my tum.
----------------
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.
-----------------
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.
great!
The best is to to have an exhaustive list of valid inference rules. The fallacious arguments are simply those that don't operate strictly on those rules. The names you wanna give the fallacies are window dressing.
so basically statements that start with "all' are invalid ONLY IF the next sentence begins with "some", "most", etc? or is it that all statements that begin with "all" are invalid?
is Denying the Sufficient Condition same thing as failing the sufficient condition?
A → B
/A
_
/B
and also is this a valid conclusion btw.
#feedback
Would be nice to have a diagram that we can open up so we can print/review
This overview is really helpful, conceptually how would you put the dashed line into words? #help
is there any videos on invalid formal arguments in v1? #help
This overview is really helpful!