The logic does not follow, a non sequitur in the example given. why not just pay for her everything? there is an obvious lack of connection between paying for a meal and paying for all expenses and no reason is given even for the action of B. If possible could you be more specific also Wenqi Guo we live in an absurd world and fallacies often win arguments unfortunately

Depending on how you word the example it could be (i) the fallacy of composition: inferring that what is true of a part is true of the whole (a part of her requirements should be paid for by you, ∴ the whole of her requirements should be paid for by you) or (ii) hasty generalization (this one of her requirements should be paid for by you, ∴ all of her requirements should be paid for by you).

Non sequitur is of course correct but it is too nonspecific in that all of the traditional fallacies involve non sequiturs, which are merely conclusions that don't follow.

I don't see a logical fallacy here.

Let's take this example:

We are in a car and we have a kid with us.

A: fastening the child's seatbelt

B: telling the child to fasten the seatbelt

In the case where everything goes fine, B is as good as A or even better because it teaches the kid to take responsibility for his own sake. However, if something bad happens, for example an accident, someone might ask "If you did B, why not A?"

Both in this example and the one given by @Wenqi Guo, there is at least one more implicit proposition that determines the direction of the whole scenario. Without making that proposition explicit, I don't see any fallacy.

Tunc Guven Kaya

Guo's example is not even an argument but a question. However, the challenge is to construct an interpretation that captures the motivation for Guo's question in the form of an argument that charitably suggests the fallacy he intuits. Guo stipulates that "A is a further version of B" and the particular example he gives as a substitution instance of "If you did B, why not A?" reflects this more-of-the-same-ness in a straightforward way. If we were to do a Venn diagram, the B cell (dinner payments) would be entirely within the A cell (payments in general), i.e. B ⊂ A. But on the face of it, fastening and telling are disjoint properties, i.e. A ⊄ B & B ⊄ A.

Thank you Mr. @Karl Pfeifer,

Would something like this work:

B: Running 500 meters

A: Running 1000 meters

And, the example might be some sort of goal to be achieved by running. For example, "John runs 500 meters to improve his physical condition. But, why not A?" or "John runs 500 meters to catch the thief, but why not A?" (Or John studied 6 years to become a medical doctor, why not 60 years?)

If this is proper, then I still feel like some implicit proposition (the distance of the thief or the current physical condition of John) should be mentioned as well in order to make it a fallacy or a sound reasoning. Am I still in the wrong?

From a Venn diagram perspective, there are three conditions I can imagine:

C (the implicit proposition or the missing part) is or can be reached from-

i- inside B

ii- outside of A

iii- inside A but not B

In the cases of (i) & (ii) it seems fallacious to say "B but why not A?" In the third case, it seems sound.

I am just taking my second philosophy course so tell me if I made mistakes in my logic.

Tunc Guven Kaya

i think the example you gave (the running and catching the thief) has already given that by doing A or B already archive something. I forgot to make this clear in my example. My example is just doing something, but such a thing does not have to archive a goal.

Another example will be:

You helped Tom with his homework; why not you just help everyone?

OR

You put some salt on the apple; why not you just put a whole can on it?

Tunc Guven Kaya

Because we are dealing with informal logic, fallaciousness will depend on context and is therefore a matter of pragmatics. If you regard the question and accompanying example as a kind of enthymeme then it will be possible to make explicit the tacit assumptions that make the argument valid; that is basically what you're suggesting with your third option.

I had said "on the face of it, fastening and telling are disjoint properties", which leaves open the possibility that more might be said. It would be interesting if you could repair your original example with a redescription that would make fastening and telling come out as instances of a property such that one of them amounts to more or less of it than the other.

Your new examples are ambiguous, insofar as they mention a goal. E.g. if John runs 500 meters to catch a thief (i.e. he catches the thief in 500 metres) then it would no longer be possible for him to catch the thief in 1000 metres since he has already caught the thief.

Karl Pfeifer

Thank you sir. I have no problems with the both analyses you gave.

You say: "Your new examples are ambiguous, insofar as they mention a goal."

That I really do because the term "why" implies some sort of 'goal' or 'purpose' or 'end' to me and I felt like it was missing in the original question. That is all I was trying to say. Then I saw the second comment by Wenqi Guo who also mentions achievement of a goal. I believe that is the part that makes this thing problematic. The term 'why' implies an extra dimension or aspect that should be explicitly investigated, don't you think so? Otherwise, I cannot imagine a scenario where we ask the question: B but why not A?

In my original example, fastening the seatbelt of the kid and telling him to do so are both methods of increasing the possibility of "a fastened seatbelt". At least that is what I was thinking. When we tell the kid to fasten his seatbelt, we are increasing that possibility. But, when we do it ourselves, we further increase that possibility. That is what I was aiming at.

Now, my question is: can we find some real life scenarios where a similar question (B why not A?) occurs and (i) it is fallacious, and (ii) it is sound? Does it depend on how we define A and B?

Thank you in advance.

Tunc Guven Kaya

Just to clarify what I take the ambiguity to be with "John runs 500 meters to catch a thief".

1st pragmatic scenario: Success: John runs 500 meters to catch a thief (and then makes a citizen's arrest of the thief).

2nd pragmatic scenario: Failure: John runs 500 meters to catch a thief (but then he so out of breath that he has to abandon the chase).

I don't understand your last question. The conventional definition of a sound argument is that (1) it is valid (i.e. it's impossible for its conclusion to be F if its premises are T, and (2) its premises are actually T. So an argument can't be both fallacious and sound.

«Such-and-such possible parental act1 would increase the probability of a fastened seat belt, ∴ all possible parental acts of increasing the probability of a fastened seat would increase the probability of a fastened seat belt»2, 3

This argument has the stipulated more-of-the-same-ness sense and would be an example of the fallacy of hasty generalization or of composition. Even if the premise and conclusion were both T in a particular case, there is no entailment between them; it would be a matter of contingency, not necessitation.

_________

1 Relevant possible parental acts might be doing it yourself, telling the kid to do it, telling the kid's sister to do it, or signalling a trained chimpanzee to do it.

2 A form of corresponding question might be «If you decide to do this possible parental act, why not decide to do all of them?»

3 Factors to take into account: some of the acts might not be conjointly doable or might have probabilities that are conditional relative to other possibilities.

The explanation is insufficient