Episode 23 picks up right where 22 left off: with Jon and Dave continuing last week’s discussion of conditional reasoning! Specifically, they ramp up the complexity and outline how to handle unusual language like “unless” statements and “either/or” constructions, make conditional chains and spot the inferences they provide, tackle scenarios with multiple sufficient and necessary elements, and even master the elusive double-arrow. This is conditionality at its highest level. … [Read more...]
LSAT Podcast Episode 22: Conditional Reasoning Part I
In the PodCast’s 22nd Episode, Dave and Jon begin what will become a multi-part look at conditional reasoning, one of the test’s most critical concepts. In this first discussion, they explore the nature of what makes statements conditional, define the key distinctions between sufficient and necessary conditions, and offer insights on making the right kind of inferences when faced with conditionality (while also avoiding the traps the test makers so frequently employ). … [Read more...]
Conditional Reasoning 101: Circular Reasoning and the Contrapositive
Students often ask great questions on our LSAT Forum.One that specifically sticks out regards the existence of circular reasoning in a question that appeared to use the contrapositive. From appearances, the question did use the contrapositive but the reasoning was still flawed, precisely because of the way it was used. Because so many become used to the contrapositive and eventually take it for granted, questions that trade on the point raised in the question can be very difficult to solve. Let's look at this in more detail. Contrapositive vs. the Logical Flaw The question is from the … [Read more...]
The Most Dangerous Conditional Rule on the LSAT
On our LSAT Discussion Forum recently, I've been running into a recurrent question about a conditional reasoning rule. These questions revolve around a really tricky phrasing, one that has devastated test takers when it has appeared on previous LSATs. But if you can learn the idea, it takes something the test makers expect to be very difficult and turns it into something fairly easy. Plus, it's not that tough to learn! So what is this mysterious but critically important concept?On the LSAT you are frequently presented with conditional reasoning. And, in many instances, the statements are … [Read more...]
How to Handle “Even If” in Conditional Reasoning (Even If it Doesn’t Matter)
Most students confront conditional reasoning very early on in their LSAT preparation. They spend hours mastering the logic of conditional rules in Logical Reasoning stimuli and answer choices, and in Logic Games as well. To this end, students must memorize a number of common conditional reasoning keywords and phrases that help indicate the presence of this logic. Some of these indicators become incredibly obvious with practice. Many of us can recall a moment when, while working through a previously unseen logical reasoning question, we encounter the all-too-familiar "if....then" construction. … [Read more...]
Conditional Reasoning 101: The Domino Effect
In a previous blog post, I talk about the basics of conditional reasoning on the LSAT. It deals with fairly simple statements involving a single sufficient condition and a single necessary condition. Though, on the LSAT, things are not always that simple! Sometimes, you will encounter conditional chains. This is where one thing is sufficient for another, which is sufficient for a third, which is sufficient for a fourth. Stringing these conditional claims together in the right order and knowing which conditions affect others and in what ways, will be crucial to your success. You will encounter … [Read more...]
Conditional Reasoning 101: As Easy as Falling Off a Log
Conditional reasoning is argumentation based on “if…then” statements and it is a prominent feature of the LSAT. While the numbers vary from test to test, year to year, you can expect around 10 questions in a single LR section that involve conditional reasoning. You’ll also see that at least half of the Logic Games will employ it as well. Some games will be entirely conditional, with every single rule setting up an if/then statement. For example, if R is on the committee, X is also on the committee; if W is not on the committee, S is on the committee, etc. Typically these will be the undefined … [Read more...]
Can You Diagram These Conditional Reasoning Phrases?
Conditional reasoning appears throughout the LSAT, in the arguments presented within the Logical Reasoning sections of the test, in the grouping games that are featured in every Logic Games section, and even (to a lesser extent) in the Reading Comprehension section of the test. This type of logic classifies conditions as Sufficient or Necessary, depending on whether they are sufficient to glean further information, or necessary for something else to be true or to occur (for an expansive discussion of conditional reasoning as it applies to the LSAT, check out the new 2016 Logical Reasoning … [Read more...]
Dealing with Negatives (Particularly Unless) in Conditional Reasoning
Today's LSAT Forum Post of the Day is a response to a student with two common questions regarding conditional reasoning statements containing negative language, like the words "unless" or "without": (1) how are those specific phrases best diagrammed, and (2) when is it possible to diagram negatively-worded statements in the affirmative? PowerScore VP of Development Jon Denning addresses both of these questions and more in the exchange that follows!Here's a quick preview. Make sure to check out the full thread to read the entire explanation Jon provided to this student:The … [Read more...]
Negating Compound and Conditional Statements
The ability to logically negate a statement—whether conditional, causal, etc.—is critical to your success on the LSAT. It comes up most commonly in the Logical Reasoning section of the test, although any question stem using the word “EXCEPT” (always capitalized) will require you to logically negate that stem. The list does not stop here: every time you apply the contrapositive of a conditional statement, you will need to reverse and negate the two conditions that constitute that statement (this is relevant to Must Be True, Justify, and Parallel Reasoning questions mostly, but can also be … [Read more...]
Conditional Reasoning Practice: Test Your Skills
The other day I came across an apparently famous logic puzzle called The Wason Selection Task. I say "apparently" famous because I for one had never heard of it, but I was instantly struck by the conditional nature of the process in question.If you're reading this I presume you've got some experience with LSAT conditionality—and if you'd like more I've included a number of helpful links at the end of this post!—so let's put your knowledge to the test.Take a look at the picture up top, where four cards are arranged before you, two with numbers, and two with colors. What you're told of … [Read more...]
Cannot Be True Questions and Conditional Reasoning
Cannot Be True questions in Logical Reasoning occasionally feature conditional reasoning (reasoning that uses sufficient and necessary conditions), and some of those questions can appear to be extremely difficult. But, as today's LSAT Forum Post of the Day shows, these questions often revolve around the same error. The test makers just dress it up a bit differently each time in order to throw off unsuspecting test takers. PowerScore LSAT Logical Reasoning Bible author Dave Killoran describes the basic error in detail, and shows you how the test makers use can make it look very different. As … [Read more...]
Beware of Keywords…
Bad advice appears well-justified and initially quite useful in solving a good number of questions. Unfortunately, shortcuts are easy to circumvent. What's worse, they can be used as traps—especially if you tend to use them blindly (as people often do). Let’s take a look at a commonly held belief about Flaw in the Reasoning questions: If you come across a Flaw question where the stimulus contains conditional reasoning, the flaw has something to do with the conditional nature in the argument. Just look for an answer choice containing such keywords as "sufficient" and "necessary," and you are … [Read more...]
Should I Study Formal Logic in College to Prep for the LSAT?
Given the emphasis on Logical Reasoning on the LSAT, students often wonder if they are missing out by not taking formal (or deductive) logic in college. Granted, some exposure to deductive logic doesn't hurt: at their best, such courses will teach you the fundamental concepts of symbolic logic, help you understand the difference between valid and invalid arguments, and train you to use symbolic language to display the logical structure of complex arguments and statements. You will probably learn to analyze truth-functions ("and", "or", "not", "if...then"), as well as quantifiers ("all", … [Read more...]