Hello! I have a very basic question. This is a bit long, but I appreciate anyone who would provide some thoughts on this.
Q: If an argument commits the necessary, but not sufficient flaw, does it also commit the sufficient, but not necessary flaw?
This question came about after I read two examples in the Trainer:
Example 1: "Everyone who boards the plane has to show his or her ticket to the attendant. Since Tom has shown his ticket, he will be allowed to board the plane."
B -> S
S
------
B
The trainer understood this to be a necessary, but not sufficient flaw (S is necessary, but not sufficient for B). But couldn't you also say that B is sufficient, but not necessary for S?
Example 2: "Every time you drink, you end up feeling sick the next day. You say you are sick today. You must have gone drinking yesterday."
D -> S
S
---
D
The training understood this to be a sufficient, but not necessary flaw (D is sufficient, but not necessary for S). But similarly, couldn't you say that S is necessary, but not sufficient for D?
When I first read this, I was very confused by the fact that two identical argument structures have two "different flaws," which is why I wonder if the two flaws are the same.
I then read this for a bit and now think that the two flaws are different. The two arguments seem to have different emphasis. What makes the first example a "necessary, but not sufficient" is the keywords "he will be allowed to board," which is different from "he must board." I think, if you were to make this change, the first example would be more intuitively a sufficient, but not necessary flaw.
"Everyone who boards the plane has to show his or her ticket to the attendant. Since Tom has shown his ticket, he must have boarded the plane."
What do you think? Since this is so foundational, I appreciate any comments about this. Thanks!
I think the problem with C here isn't just that it's attacking the premise. If C had said "many people are allergic to herbs," then I think it's a great weaken answer against the conclusion you should always use herbs.
The problem is the "certain medicine", which could include herbs, but also could not. We don't know if herbs are included. To see this using an analogy, suppose the argument is: "Because ice cream tastes good, you should always eat it." C would be like saying, "Certain foods are very salty and do not promote health."