LSAT and Law School Admissions Forum

Get expert LSAT preparation and law school admissions advice from PowerScore Test Preparation.

  • Posts: 6
  • Joined: Aug 16, 2014
YES, I am posting yet another thread on the SAME page of the LR Bible! But I am on my second review of the bible, having completed a number of PTs, and am here for more clarification!

What I seek help with in regards to causes that increase/decrease force of effect or increase/decrease the likelihood of the effect is this: how do we diagram these correctly? More specifically, how do we diagram the 'contrapositives'?

First of all, do causal diagrams have the same rules of contrapositives? Or do we have more flexibility? What degree of flexibility, if so?

An example Q is PT 37, Section 4, Q15. We are dealing with decreasing feelings of guilt, decreasing transgressions, and increasing severity of legal penalties.

I found myself mapping out the Q with diagrams & preventing myself from doing Mistaken Reversals & Mistaken Negations. But must we only rely on contrapositives for such causal diagrams?

It would be very helpful to know the correct diagramming methodology for dealing with increases/decreases causality for this question as a model for others. If someone would be able to map out how to deal with this question as a model, I would be very thankful!

Thank you!
 Jon Denning
PowerScore Staff
  • PowerScore Staff
  • Posts: 904
  • Joined: Apr 11, 2011
Hey sonnenstrahl,

Thanks for the questions, and don't sweat the multiple posts!

My advice is that you should generally stick to treating conditional reasoning and causal reasoning separately, as causal reasoning is not only MUCH easier to deal with in most instances, but it also tends to follows different rules. (I should mention of course my reply to your other post about sufficient/necessary causes as necessary causes could be considered a very slight exception, so please read the supplement I directed you to there)

For instance, you talk about contrapositives and diagramming. Those are applicable to, and consistent in, conditional reasoning because the necessary condition must be present as given when we have the sufficient (so its absence removes the sufficient), and because the relationship is one-directional. That's why Mistaken Negations and Reversals are "mistaken": you cannot treat the necessary as universally connected to the sufficient, since the necessary can appear without the sufficient.

But in typical causality that's not true! That is, if you see the effect, the author would have you believe the cause, and only the cause given, MUST have led to it (must be present). Thus the relationship is essentially bi-directional, where either cause or effect tells you the other is there. This also lies at the heart of causality's flaws, since showing either one without the other, or showing any other cause for the effect, destroys the argument.

My point in all of this is that "contrapositives" are true in causality--no effect means no cause in the author's eyes--but less useful, since they aren't the ONLY truth like you'd have in conditionality. So in the sense of more relationships being known from a causal statement, yes there's a lot more flexibility, as the Mistaken Negation and Mistaken Reversal ideas from SN would apply as well.

But again, better I think not to treat them so similarly, and instead view causation independently.

With that in mind I'd also encourage you to avoid diagramming causality with an eye to inferences (like a contrapositive or chain in conditional reasoning), and more, if you're going to diagram at all, to simply note the original relationship. A :arrow: B just means the author thinks A is the cause of B, and any other arrangement would then be problematic: alt cause, reversal, one without the other, etc.

Finally, there's also a great discussion on avoiding conflating causal reasoning with conditional reasoning here: ... ause#p5446

I hope this helps!

  • Posts: 6
  • Joined: Aug 16, 2014
Thank you so much for your detailed response. Extremely helpful!

Get the most out of your LSAT Prep Plus subscription.

Analyze and track your performance with our Testing and Analytics Package.