Inference and Assumptions

[Kmikaeli]

Within must be true type questions, I noticed that we must make an inference based on the facts stated in the stimulus. Hence why we paraphrase them or link statements togehter and etc...

However, aren't supporter assumptions, which are linking new or rogue materials the same thing as a type of inference (must be true question) since we are linking statements within the conclusion and premise to establish the assumption, which feels like an inference to me?
Also, if supporter assumptions are linking new/rogue material together, like justify the conclusion questions, doesn't that make it an inference since assumptions are new information not from stimulus?

I understand an inference occurs after the stimulus is complete in which case you are linking or paraphrasing material within the statements to establish a conclusion/aka must be true inference.

however, in assumption questions you are trying to find the missing gap between the premises and conclusion to establish the unstated premise. The only problem is that do both inference and assumption questions involve a process of linking new materials in the same manner?

Lastly, can you please explain a necessary and sufficient assumption?
I know that justify the conclusion questions work with sufficient assumptions, but how do assumption type questions work as, necessary or sufficient)?

[Dave Killoran]

Hi Kmikaeli,

Assumptions do feel very much like inferences! The difference is that Assumptions are made by the author during the formation of the argument. Inferences, as you correctly note, follow once the argument has been made. So, I often think of it as the difference between before and after: assumptions are made before the conclusion is made and the conclusion rests on them, inferences are made after conclusion.

As far as necessary and sufficient assumptions, this forum is a bit limited for me to explain those, but the good news is that explanations are in the LRB! Justify questions use sufficient assumptions—you are adding the key piece of information that makes the conclusion occur. Assumption questions use necessary assumptions—the piece of information the argument needs for the conclusion to be workable. The difference between the two answer types is some often small, and in many cases the same answer would work for both functions (see the LRB discussion on this—I go into great detail about it).

Thanks!

[Kmikaeli]

Which page or section is it on in the LRB 2014 edition?

Also is the process of finding the assumption the same as inferences? For instance linking the new elements is a supporter assumption aka mechanistic approach.

[Kmikaeli]

Actually I might've got it. So, assumption questions require a necessary assumption hence why a sufficient condition is not stated within the question while justify the conclusion question requires a sufficient enough assumption. While both rely on assumptions, they can often intertwine where a necessary assumption can be the sufficient for in the case of justify the conclusion.

As for inferences, they occur at the end of the stimulus where you either paraphrase certain statements, combine ideas or statements (through conditionality etc...) like the supporter assumption approach or through the linkage method of conditional statements and thus establish an inference. Assumptions work in a similar manner but they follow through two roles which is supporter and defender roles.

Defender assumption defends you from assuming that a necessary assumption does not occur by bringing in defense mechanisms such as causality strengthening or necessary condition importance.

Supporter assumption tend to appear in both must be true, assumption, and justify the conclusion questions. The only difference is that must be true questions establish such a linking role after the argument is complete while assumptions work to like the rogue elements of premises and conclusion to establish an assumption to place before the argument.

[Dave Killoran]

Actually I might've got it. So, assumption questions require a necessary assumption hence why a sufficient condition is not stated within the question while justify the conclusion question requires a sufficient enough assumption. While both rely on assumptions, they can often intertwine where a necessary assumption can be the sufficient for in the case of justify the conclusion.

Yes, that is basically correct.

As for inferences, they occur at the end of the stimulus where you either paraphrase certain statements, combine ideas or statements (through conditionality etc...) like the supporter assumption approach or through the linkage method of conditional statements and thus establish an inference. Assumptions work in a similar manner but they follow through two roles which is supporter and defender roles.

Do you mean "after you've read the stimulus" perhaps? Because inference-generating statements can be placed anywhere in the stimulus.

Defender assumption defends you from assuming that a necessary assumption does not occur by bringing in defense mechanisms such as causality strengthening or necessary condition importance.

Well, they don't defend you, they defend the argument against ideas that could attack it. If that's what you were saying, then yes

Supporter assumption tend to appear in both must be true, assumption, and justify the conclusion questions. The only difference is that must be true questions establish such a linking role after the argument is complete while assumptions work to like the rogue elements of premises and conclusion to establish an assumption to place before the argument.

Here's where you've tangled ideas together in a way that makes me uncomfortable. You are using the word "assumption" to also mean "inference" here, but as we've established, they do have different meanings. I believe what you are driving at, however, is the before/after difference I described earlier. If so, that is still the case.

Second, Must be True questions shouldn't be included in this list. While many stimuli attached to Must question have assumptions, some are just fact sets, and you wouldn't characterize them as tending to have Supporter Assumptions (but as noted in the prior paragraph, they would yield inferences). Limiting our analysis to what's most useful to the LSAT, if you're focused on just the assumption idea, you'd switch out Must questions and replace them with other types that always contain arguments, like Strengthen and Weaken.

Thanks!

[Kmikaeli]

So after the argument is made you make the inference based on the information in the stimulus, which can be placed anywhere (ie conclusion premise etc..)

Assumption based questions look at the connection between the premises and conclusion to establish such assumption which is placed in the premises to complete that gap/hole.

Also i understand that must be true questions do not usually have conclusions, but the process of solving for inferences is almost exactly the same manner for solving assumptions.

[Dave Killoran]

So after the argument is made you make the inference based on the information in the stimulus, which can be placed anywhere (ie conclusion premise etc..)

Yes, the inference could be generated from anywhere.

Assumption based questions look at the connection between the premises and conclusion to establish such assumption which is placed in the premises to complete that gap/hole.

Yes, that is how Supporter Assumptions work.

Also i understand that must be true questions do not usually have conclusions, but the process of solving for inferences is almost exactly the same manner for solving assumptions.

I personally wouldn't say that the process of solving each is almost exactly the same because they are different and you can't use the Assumption Negation Technique on inferences (which tells you they have a fundamental difference). However, the key here is for this to make sense to you, and I think so far it has, and from what
I know of your thinking I believe I understand what you are getting at

[Kmikaeli]

Yeah, i didn't mean exactly, i meant quite similar in terms of linking rogue or new information applies to both inferences and assumptions in a manner that is similar. the only difference is the before and after situation for both cases and how one has a conclusion and the other one does not for the most part.

I am sure i get it because i am scoring quite well on must be true portions.