Aggressive Conditionals: Mary's Choice -- Can you help?

[chike_eze]

I've worked on LR and LG questions that use "OR" in creative ways. Sometimes I get tricked, especially when I expect one conditional form, but the LSAT is looking for another.

Here are a few of them...

Mary will go to the Shop or watch a movie
Mary will either go to the shop or watch a movie
Mary will either go to the shop else she will watch a movie
Mary will go to the shop but she will not watch a movie
Mary will go to the shop and she will watch a movie

If Mary does not watch a movie, she will not go to the shop
If Mary does not watch a movie, she will go to the shop

Could you help translate these sentences into "or", "and" or conditional statements
> M = Mary, S = Shop, W = Watch movie

Thanks!

[demetri.blaisdell]

Good to keep everyone on their toes with some conditional practice. Be careful though, not all of these are conditional statements.

Mary will go to the Shop or watch a movie
W or S or both (could be part of a conditional - on the LSAT, or includes both unless otherwise noted)

Mary will either go to the shop or watch a movie
W or S but not both (could be conditional depending on context - either could be enough to indicate not both, but the LSAT would be more likely to tell you not both)

Mary will either go to the shop else she will watch a movie
S <--> -W (this is a biconditional and this is LSAT language)
W <--> -S (contrapositives - this is actually 4 separate relationships which I am writing as two biconditionals)

Mary will go to the shop but she will not watch a movie
S, -W (not conditional)

Mary will go to the shop and she will watch a movie
S, W (not conditional)

If Mary does not watch a movie, she will not go to the shop
-W --> -S (conditional - two nots are unusual on the LSAT)
S --> W (contrapositive)

If Mary does not watch a movie, she will go to the shop
-W --> S (again conditional)
-S --> W (again contrapositive)

Nice exercise here. Let me know if you disagree with any of my diagramming and we can discuss them. Also, if you want more practice with conditionals, check out the advanced conditionals workshop located at:

https://www.manhattanlsat.com/class_resources.cfm (look under Class Labs)

Happy conditional-ing!

Demetri

[chike_eze]

Good to keep everyone on their toes with some conditional practice. Be careful though, not all of these are conditional statements.

I agree.

Mary will either go to the shop else she will watch a movie
S <--> -W (this is a biconditional and this is LSAT language)
W <--> -S (contrapositives - this is actually 4 separate relationships which I am writing as two biconditionals)

I need to think about your bi-conditionals a bit more. It's a bit confusing to me right now.

Here's my take on all statements. Provide feedback when you get a chance.

W = Mary watch a movie
S = Mary go to the shop

Mary will go to the Shop or watch a movie
> (Inclusive OR) S or W or (S and W)

Mary will either go to the shop or watch a movie
> (Inclusive OR) S or W or (S and W)

Mary will either go to the shop else she will watch a movie
> (Exclusive OR) S or W
> Inference: S --> -W,
> Inference: W --> -S (contrapositive)

Mary will go to the shop but she will not watch a movie
> S and -W

Mary will go to the shop and she will watch a movie
> S and W

If Mary will watch a movie, she will not go to the shop
> W --> -S
> S --> -W (contrapositive)

If Mary does not watch a movie, she will go to the shop
> -W --> S
> -S --> W (contrapositive)

[demetri.blaisdell]

Those look good. The only one that could be different is:

Mary will either go to the shop else she will watch a movie

This one could be a biconditional but, depending on context, it could also be exactly how you diagramed it above.

I think it's good you are practicing your conditionals, but be careful about spending too much time focusing on vocabulary (if I see "or" and "else" it is this, if I see "or" without "either", it's different). If you become a conditionals robot, you might diminish your greatest tool: intuition. For more practice, consider working on Binary Grouping games or LR Inference questions. These will test your understanding of conditionals in context. We want the contrapositives to become like a reflex, but if you spend an extra 5 seconds on test day to double check you understanding of the conditional relationship, it will be time well spent!

Demetri