Logical Reasoning Question Types-Supposition

The supposition problem types found in the logical reasoning (arguments) sections of the LSAT fall into the appraisal category.

Supposition problems are denoted by the fact that they call for the examinee to identify the lacking element that will make the stated argument logical. It is very easy to confuse supposition problems with inference problems because both types of problems require the examinee to supply something that is not given in the passage of the problem. The major difference between the two is that supposition problems require the examinee to provide the missing piece to an argument, whereas an inference requires the examinee to determine the logical consequences of given premises in the argument provided.

As a starting place, an example of a simple supposition should be considered. Consider this example:

Bobby is allergic to chocolate ice cream. Therefore, Bobby loved going to the Ice Cream Parlor because he could eat all of their offerings.

Please keep in mind that this is a greatly simplified example intended to provide an introduction to this concept. Having said that, it should be fairly simple to identify that there is a missing piece of information that would make the above proposition complete. This missing piece is the fact that the Ice Cream Parlor does not offer chocolate ice cream. Therefore, this would be the proper selection from the answer choices provided.

As is the case with many problems on the LSAT, the trick is identifying what type of problem is posed. To identify a supposition problem, the examinee should look for the word "assumption" or some derivative thereof. For example, the question stem may ask the examinee "What fact is assumed in the above argument" in the answer stem. Probably the best and simplest method for approaching supposition problems is to play the role of "Doubting Thomas." That is, be skeptical. This method has its bounds. The examinee should not discount everything that is unwritten in the passage, but the examinee should look for alternatives to the reasoning used in the passage that could negate the argument. It is a good practice for the examinee to ask "what if…" to determine if there is something missing from the argument.

How this strategy plays out can be seen when looking at an actual problem and its answer choices. Because a supposition requires an additional piece of information to be correct, the examinee can walk through each answer selection and consider the argument provided without each answer selection. When an answer selection is reached that cannot be dispelled without ruining the argument, the correct answer has been found.

Continuing with our Ice Cream Parlor question from above, if that were an actual problem on the LSAT, then there would be several answer choices. Each of these answers would be irrelevant, overly broad, unnecessary, or correct. Once the examinee comes to the answer selection that said something like "The Ice Cream Parlor does not serve chocolate ice cream" the examinee should quickly identify that dispelling this statement destroys the argument. Therefore, the proper answer selection has been found.