Discussion
If Fred's statements are true, which of the following can be concluded?
*This question is included in Exercise Set 2: Intro to Negation, question #6
| (A) | Fred has felt better than he does today. |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 08/15/2011 12:59
In the content prior to the exam, they discuss "converse error". Why is this (the solution) not an example of that?
Posted: 08/15/2011 18:00
The answer follows from the contrapositive.
Since we have:
AD --> FLH
And:
~FLH
We can conclude that we have:
~AD
This is the same as saying that we CANNOT have "AD", which is true because we MUST have "FLH" if we have "AD", and we know we don't have "FHL".
How is this different from the converse error?
The original conditional statement is:
AD --> FHL
The contrapositive is:
~FLH --> ~AD
The converse error would be:
FLH --> AD
The converse error creates a relationship not supported by the argument. You can't say that (based on the argument) it's true that if Fred "felt like hell", it MUST be because he had "another drink."
Since we have:
AD --> FLH
And:
~FLH
We can conclude that we have:
~AD
This is the same as saying that we CANNOT have "AD", which is true because we MUST have "FLH" if we have "AD", and we know we don't have "FHL".
How is this different from the converse error?
The original conditional statement is:
AD --> FHL
The contrapositive is:
~FLH --> ~AD
The converse error would be:
FLH --> AD
The converse error creates a relationship not supported by the argument. You can't say that (based on the argument) it's true that if Fred "felt like hell", it MUST be because he had "another drink."
Posted: 12/09/2011 19:10
He said if he had another drink he would feel like hell and he meant it but he could have been mistaken about that so I find it impossible to conclude that he abstained.
Posted: 12/09/2011 19:15
If they said Fred will feel like hell if he has another drink I would agree...but it merely says he said that and meant it. This only means he expects that he will feel like hell if he has another drink. I have expected that last drink to make me feel like hell and then awoken the next morning feeling fine.
Posted: 12/11/2011 22:35
Rachel,
Yeah, this one might need to be refined a bit.
Here's the new text:
Frathouse Fred:
Last night I said "If I have another drink, I'll feel like hell tomorrow", and I always speak the truth. But today, I am pleased to announce I feel okay.
Yeah, this one might need to be refined a bit.
Here's the new text:
Frathouse Fred:
Last night I said "If I have another drink, I'll feel like hell tomorrow", and I always speak the truth. But today, I am pleased to announce I feel okay.
Posted: 12/11/2011 22:36
Expect the edited text to appear in the next update.
Good catch Rachel. Thanks.
Good catch Rachel. Thanks.