When a game has conditional rules with elements in common, try to link the rules into one big chain.The key to this type of game is to create a chain with the rules. When several conditional rules seem to link together, try to combine them into one large chain.
When you begin to link rules together, do not worry about which rules you should start with. You’ll end up with the same chain and contrapositive no matter where you begin.
We’ll begin with the first rule about Harriers and Grosbeaks and combine it with the second rule, which also contains Harriers.
Notice that we separated the Jays and Martins into two different arrows, since either Jays or Martins will tell us that we have Harriers in the forest. We separate them because we may need to combine other rules with either Jays or Martins independently.
Since the third rule says that if Wrens are in the forest, so are Grosbeaks, we can know that if Grosbeaks are not in the forest, neither are Wrens (the contrapositive of the third rule). Thus, we can attach “not Wrens” to the end of the chain.
The final rule says that if Jays are not in the forest, then Shrikes are. This means that if Shrikes are not in the forest, then Jays are (this is the contrapositive of the fourth rule). We can attach this deduction to the front of the chain.
Now that all the rules have been used, create the contrapositive of the chain by reversing and negating the entire chain.
Arrows are ONE Way! Don't follow them backwards, or you'll get questions wrong! Now we’re ready to answer the questions. As you answer, be sure to only follow the arrows from left to right. DO NOT follow them backwards!
Question 6: Since this question talks about birds NOT in the forest, look at the “nots” in the chain. For example, if S is NOT in the forest, then J and H are in the forest and G and W are NOT in the forest.
Look at the answers. In A, D, and E, Shrikes are in the NOT list, but in choices A and E, Grosbeaks and Wrens don’t appear. Thus, these choices are incorrect and can be eliminated.
Keep looking at the top chain, and find the next “not”. It’s “not G”. If Grosbeaks are in the list of birds NOT in the forest, then Wrens should also be in the list of birds NOT in the forest.
Look at the answers. (Ignore A and E, since they have been eliminated.) Choices B and C have Grosbeaks in the list, but do not have Wrens. Thus, these choices are also incorrect and can be eliminated. This means that D is the correct answer, since it is the only answer choice left.
Question 7: Since the question asks what must be true if Martins are in the forest, look at your chain and find M. Now, you need to look only to the RIGHT of Martins. Ignore everything to the left; those birds could go anywhere (In or Out of the forest). I like to cover up everything to the left with my fingers like this:
The chain shows us that if Martins are in the forest and Harriers are in the forest and Grosbeaks and Wrens are not in the forest. Thus, we cannot infer A, B, or C. We simply don’t know where Jay and Shrikes are.
We don’t know (D), that at least two other kinds of birds are in the forest, because we don’t know where Jays and Shrikes are.
We DO know E is true, since Grosbeaks and Wrens are NOT in the forest, the maximum number of other kinds of birds that can be in the forest is two (jays and shrikes).
Question 8: Since this question begins with “If jays are not in the forest…” find the chain with “not J”, and cover up everything that “not J” doesn’t point to.
We can see that the ONLY thing we know if Jays are not in the forest is that Shrikes are in the forest. Thus, choice D must be false and is the correct answer.
Question 9: To answer this question, try to get the most birds into the forest that you can by using the original chain, then its contrapositive.
Pick the first “in” bird in each chain. For example, in the top chain, Jays are the first “in” bird, and if Jays are in the forest, so are Harriers. Shrikes and Martins could also be in the forest (it IS possible for Jays and Shrikes to both be in the forest, they just can’t both be NOT in the forest.) This is a maximum of 4 birds if Jays are in the forest.
Now compare that to the bottom chain. In the bottom chain Wrens are the first “in” bird, and if Wrens are in so are Grosbeaks and Shrikes. No other birds can be in. This is only three birds, so the maximum number of birds in the forest must come from the other chain and is four: Jays, Harriers, Shrikes, and Martins.
Question 10: For this question, simply look back at the chain to see which pair of birds can’t be in the forest together. Choice A is the correct answer, since if Jays are in the forest, Wrens cannot be in the forest.
(Choice B is incorrect, because Shrikes and Jays CAN be in the forest together. The rule says only that if Shrikes are NOT in the forest, then Jays must be. So the two birds can’t both be gone, but that CAN both be present in the forest together.)
Question 11: Since the question begins with “If grosbeaks are in the forest…” find G in your chain and cover up everything G does not point to.
Following the chain shows us that Shrikes must be in the forest, so A is the correct answer.
Question 12: This question adds an extra arrow to our chains. It creates a fun little loop.
Choice A -- The forest cannot contain both Jays and Shrikes, since J leads to H, which leads back to 'not S'.
Choice B -- The forest CAN contain both Wrens and Shrikes. This is the correct answer.
Choice C -- The forest cannot contain both Martins and Shrikes, since M leads to H, which leads back to 'not S'.
Choice D – Not J leads to S, which leads back to 'not H', which leads to 'not M', so it cannot be true that Jays are not in the forest and Martins are in the forest.
Choice E – In the top chain, G, W and at least one other bird will not be in the forest, since H and S cannot both be in the forest (If H is in, S will be out). In the bottom chain, H, J and M will not be in the forest. Thus, at least three of the six kinds of birds will not be in the forest.
Other LSAT articles you may find useful:
A Few Ideas for Dealing with Test Anxiety on the LSAT
5 Tiny Mistakes on the LSAT that can cost Big Points
A Sample Logic Game
This solution is copyrighted 2007 by Griffon Preparation Services, LLC. No reproduction -- either written or electronic -- is permitted without prior permission from Griffon Prep. The LSAT game for which the solution is offered is an actual game published by LSAC, which appeared on the December 2000 LSAT test.