Additional Premise and Counter-Premise Recognition Mini-Drill

[jupiterlaw]

Hi!

I am working on the logical reasoning bible and have some nit-picky questions about this mini-drill as I want to make sure I have a full understanding of facts, premises, and additional premises.

1. I understand the difference between premises and counter-premises but additional premises are a little grey to me. I am unclear if there is actually a significant difference between premises and additional premises or if they mean the same thing and the wording is simply different for a reason that is not of any significance to building or understanding the argument.

For example, in Q1, the answer key notes that, "These wineries claim the unfiltered juice ultimately produces a more flavourful and intense wine." and "Since these wine makers are experts," are premises.

However, in Q2, the answer key notes that, "there are dangers associated with phenylketonuria, and products containing phenylalanine must carry a warning label that states, 'Phenylketonurics: contains phenylalanine." is a premise, but "In addition, all children in developed societies receive a phenylketonuria test at birth." is an additional premise.

I am not understanding the difference between premises and additional premises here. To my understanding, both arguments have an initial "premise" and two "additional premises", clearly this is incorrect so I am looking to understanding this.

2. I am unsure why the first sentences of both Q1 and Q2 are premises and not just facts. Are these considered premises and not facts simply because they are part of an argument and not a fact set? Or is there more to this?

[jupiterlaw]

Mainly my confusion is coming from the fact that in the first explanation of additional premises it is noted that they are, "...another premise that supports the conclusion but is sometimes non-essential to the conclusion." I can understand in cases where it is non-essential to the conclusion that you could decipher between a premise and an additional premise, but it says sometimes. In cases where the additional premise is essential to the conclusion how can you tell the difference between it and a premise, or are they in this case the same thing and the terms interchangeable?

[Robert Carroll]

jupiterlaw,

Whether a premise counts as "additional" or not is really just a rhetorical matter. It does not have logical significance. Anything the author thinks helps the conclusion is a premise. The author may introduce some of that information using wording like "besides that," "additionally," or things like that, but the author wouldn't regard the logical force of their own argument changed by dropping those phrases and just introducing the premises normally, so there's no important difference there for LSAT purposes.

The information in the first sentences is part of the factual basis for the conclusions of both arguments. Those sentences are properly labeled "premises" for that reason. A premise can be, an in fact usually is a fact. To tell whether a fact is a premise or something else just means asking whether it's part of the factual basis for the conclusion - those sentences are, so they are premises.

Whether a premise is essential to a conclusion or not is a pretty important thing, but since, as noted, the term "additional premise" does not correlate with whether a premise is essential, it's better to think of premises which are essential to the conclusion and those which aren't, not concerning yourself with whether they are "additional" premises.

Robert Carroll

[Dave Killoran]

If I can slightly refine Robert's response, the idea of an Additional Premise is indeed one where it is still a premise, and all premises support the argument's conclusion. Logically, though, in many instances the author has used additional indicator language to signify that the additional premise isn't the central pillar of the argument. Meaning that it could be taken away without damaging the argument. For example:

• Conclusion: Our school fundraising party is a success!
  
  Premise: We already have surpassed the donation target for the evening and we still have a few hours to go.
  
  Additional Premise: Plus, everyone has been having a great time.

You can take away that Additional Premise and the party is still a success based on the information in the Premise. Does the Additional Premise add to the conclusion? Sure, it adds a different measurement of success that helps support the overall conclusion. However, I'd argue that the Additional Premise is less important than the Premise. And the reason why is that in the conclusion it is stated that the "fundraising party is a success," so we know this was a financially-oriented event.

In other words, authors do know that some premises are more important than others and the Additional Premise language is one way they can convey that. There are exceptions of course--the English language is so malleable that almost anything can be conveyed using "standard" terms like these. But, in the case above, consider what happens if you remove the Premise: the argument would be weaker because the Additional Premise doesn't address the financial aspects of the conclusion. So, in comparing just the Premise/Conclusion structure vs just the Additional Premise/Conclusion structure gives us two arguments that have different strengths. And that shows how Additional Premises are often add-ons that help the argument but aren't as strong as the initial premises given.

Thanks!

[jupiterlaw]

Thanks! That makes a lot more sense now, I understand why in Q#3 in this mini-drill one statement is an additional premise and one is a "main" premise, but I still do not really understand this for Q#2.

Why is "In addition, all children in developed societies receive a phenylketonuria test at birth" (the additional premise) less important to the conclusion than the other two premises describing what/who phenylketonurics are and that products containing phenylalanine must have a warning label. Is this because it is done only in "developed societies"?

I understand that "in addition" indicates that the statement is an additional premise but I am thinking if this were on the LSAT without an indicator how you could determine the "test at birth" statement to be less important to the conclusion as the other two? It seems pretty important to doing as much as possible to protect against this condition, since the first step in protecting people with a condition is knowing that they have it.

I may be overthinking this so if knowing this difference won't have an impact for any question type please let me know, but I figured since the LRB takes time to explain the additional premises that there is a reason for learning this distinction.

Thanks!

[Robert Carroll]

jupiterlaw,

The only situation where I can see the difference between "premise" and "additional premise" mattering is for a Method - Argument Part question. If one answer said something like "a premise essential to the argument" and another answer said "a premise whose denial is consistent with the argument's conclusion", that would seem to be expressing something like the difference between a premise and an additional premise. In my 10 years of experience with PowerScore, I can't remembering seeing anything that fits that exactly.

It's not uncommon for the author of a stimulus to present information they agree with, but don't want to agree with, since it's apparently bad for their conclusion. We call that a counterpremise. An additional premise isn't like that - it's actually good for the argument, it appears good for the argument, and the author is happy to have it along as info - the author just wouldn't rest solely on that, if the author could help it. Thus additional premises are never the only premise of an argument. Rarely, if ever, does the answer to an LSAT question depend on differentiating what the author regards as essential and what the author regards as helpful but not essential. The one exception to that is an Assumption question, but in that case, the Assumption isn't stated in the stimulus anyway! So, again, I think the distinction is good to know to "get into the author's head" and figure out how LSAT LR arguments work in general, but misidentifying a Premise as an Additional Premise, or vice versa, is unlikely ever to make a difference in getting a question right.

Robert Carroll

[jupiterlaw]

jupiterlaw,

The only situation where I can see the difference between "premise" and "additional premise" mattering is for a Method - Argument Part question. If one answer said something like "a premise essential to the argument" and another answer said "a premise whose denial is consistent with the argument's conclusion", that would seem to be expressing something like the difference between a premise and an additional premise. In my 10 years of experience with PowerScore, I can't remembering seeing anything that fits that exactly.

It's not uncommon for the author of a stimulus to present information they agree with, but don't want to agree with, since it's apparently bad for their conclusion. We call that a counterpremise. An additional premise isn't like that - it's actually good for the argument, it appears good for the argument, and the author is happy to have it along as info - the author just wouldn't rest solely on that, if the author could help it. Thus additional premises are never the only premise of an argument. Rarely, if ever, does the answer to an LSAT question depend on differentiating what the author regards as essential and what the author regards as helpful but not essential. The one exception to that is an Assumption question, but in that case, the Assumption isn't stated in the stimulus anyway! So, again, I think the distinction is good to know to "get into the author's head" and figure out how LSAT LR arguments work in general, but misidentifying a Premise as an Additional Premise, or vice versa, is unlikely ever to make a difference in getting a question right.

Robert Carroll

Thanks, that helped a lot!