77 comments

  • Tuesday, May 21, 2024

    This is how I'm understanding this:

    1. A conditional statement is typically expressed as: "If A, then B" (A → B). The contrapositive of this statement is: "If not B, then not A" (/B → /A).

    2. Example to illustrate:

    - Conditional Statement: If it is raining (A), then the ground is wet (B).

    - Contrapositive: If the ground is not wet (/B), then it is not raining (/A).

    3. Applying the Contrapositive in Arguments:

    - Conditional Statement: If A, then B (A → B)

    - Observation: X is not in B (/B)

    - Conclusion: Therefore, X is not in A (∴ /A)

    30
  • Edited Saturday, Jan 24

    At first I felt like some of these videos are super repetitive. Now I see that I never would have understood that if Luke is a Jedi and Jedi use the force that Luke uses the force.

    Contradictorily

    If Luke cannot use the force and Jedi use the force. Luke is not a Jedi.

    Beginning to learn I am.

    17
    Tuesday, Feb 3

    @fjnathaniel This is the way.

    5
  • Wednesday, Mar 11

    All these math symbols are throwing me off

    9
    Saturday, Mar 21

    @SofiyaBerman yea im over all that, ill see how i fare

    1
  • Tuesday, Apr 15, 2025

    Premise 1: if a plant is a flower, then it is pretty.

    Premise 2: the plant is not pretty.

    Conclusion: the plant is not a flower

    Is this correct ???

    9
    Thursday, Apr 24, 2025

    Looks good to me:

    F→P

    /P

    ------

    /F

    3
  • Sunday, May 31

    Does anyone feel like these kind of mental gymnastics are like equations? In that case, I'm not a fan of this kind of math lol. All I can deduce this is into is just standard sentences: Anyone who eats expired food--> gets sick. I ate expired food. Therefore, I get sick.

    8
  • Monday, Jun 2, 2025

    All dogs are cute

    Joe is not cute

    Joe is not a dog

    8
  • Saturday, May 9

    I wrote off me and contrapositives a looooong time ago, but this actually makes sense!!

    7
  • Friday, Jun 19

    I UNDERSTAND 🤝🏾

    6
  • Tuesday, Aug 26, 2025

    If one has supernatural powers, they've eaten a devil fruit. SP-->DF

    Luffy has supernatural powers. l^SP

    Luffy has eaten a devil fruit. l^DF

    Contrapositive:

    SP-->DF

    Usopp does not have supernatural powers. u^/SP

    Usopp has not eaten a devil fruit. u^/DF

    6
  • Friday, Oct 4, 2024

    All Canadians like Don Cherry's suits.

    John doesn't like Don Cherry's suits.

    John isn't Canadian.

    6
  • Monday, Mar 9

    if one is a dancer, then one is an athlete.

    D > A

    Mike is not an Athlete

    m^/A

    ________

    m^/D

    Therefore, Mike is not a dancer

    5
  • Wednesday, Feb 12, 2025

    #feedback Some of the videos allow you to switch to full screen, fast forward, change the speed, etc. while other videos do not. I tried refreshing the page but that only worked once. Can this issue be resolved?

    5
  • Friday, May 8

    If the subscript is messing some people up, in my mind, writing out the contrapositive statement is really helpful. At the end of the day, we can only move from the left side of the arrow to the right. If we diagram that out clearly, I think it is difficult to go wrong

    A --> B

    X = A

    X --> B

    is the same thing as

    A --> B

    /B --> /A

    X --> /A

    4
  • Thursday, Apr 30

    I remember taking a logic class in college and we used the negation symbol as this ~ and not the slash/. I think the slash is throwing me off in these lessons a little bit. Either way I am realizing that logic class actually helped me a lot.

    4
  • Thursday, Oct 3, 2024

    Using slashes instead of just crossing things out is kinda silly and prob confuses new students a little.

    4
  • Sunday, Jul 19

    I am truly hoping I don’t NEED this lawgic to pass. This has made more sense in words and I really do not need formulas to add to the confusion.

    3
    Thursday, Jul 23

    @ElyS agreed

    2
  • Sunday, May 31

    Makes sense mostly.

    3
  • Saturday, Nov 8, 2025

    modus tollens

    p-->q

    ~q

    therefore ~p

    3
  • Sunday, Feb 22

    If one eats a thousand donuts, then one must perform in the circus

    TD>C

    Nina did NOT perform in the circus

    n^/C

    ------

    n^/TD

    Therefore, Nina did NOT eat a thousand donuts

    4
  • Friday, Jun 26

    so is there a contraposition argument within a conditional argument if you negate or are they two separate things

    2
  • Edited Wednesday, Jun 17

    Has anyone else found it easier to just rename the visual sets to /(variable) and inverting the set order when doing lots of work on contrapositives?

    2
  • Edited Tuesday, Apr 14

    If one prepares for the LSAT, then one is going to law school. Sarah is not going to law school; therefore, Sarah does not prepare for the LSAT.

    LSAT→LS

    s/LS

    ______

    s/LSAT

    2
  • Wednesday, Sep 10, 2025

    So is it fair to say that the conditional form represents a sufficient argument and the contrapositive form represents a necessary argument?

    2
  • Tuesday, Feb 11, 2025

    Question: How would I use this on the LSAT? They show visuals on the test?

    2
    Wednesday, Feb 12, 2025

    No, but you can create the visual yourself if you'd like. It's just to better organize the form of the argument and the relationship between different premises.

    0
  • Friday, Jan 31, 2025

    I feel like the explanation is super wordy simply it is

    a conditional statement

    If one lives in NYC than they live in the USA

    NYC → USA

    Contrapositive just flip and slash

    /USA → /NYC

    so NOT in the USA than NOT in NYC

    in a statement, the contrapositive is as follows

    If one lives in NYC then one lives in the USA. Dave does not live in the USA. Therefore Dave does not live in NYC. As you can see from our contrapositive statement above this follows that exact form. This is valid.

    2
    Wednesday, Mar 19, 2025

    I was thinking this too. I was actually confused that an additional person was brought in when it could've simply been if one does not live in the united states then they do not live in NYC.

    0

Confirm action

Are you sure?