Naturalist:  The recent claims that the Tasmanian tiger is not extinct are false. The Tasmanian tiger's natural habit...

AndreaK on March 13, 2020

Hi @AMS,

Let me see if I can help with this! This is a necessary assumption question. That means we are looking for the answer choice that gives information that has to be true in order for the argument’s conclusion to be at least possible.

Let’s break down our argument and analyze the relationship between premises and conclusion.

Conclusion: The recent claims that the Tasmanian tiger is not extinct are false.

In other words, this conclusion is saying that the Tasmanian tiger IS in fact extinct and does not presently exist.

Premises (or evidence meant to support that conclusion):
1. Habitat was taken over by sheep farming decades ago resulting in elimination from the area
2. Since then naturalists have not discovered hard evidence of it (carcasses or tracks)

Okay, so our argument is trying to convince us that this tiger isn’t alive. It’s reasoning is that its habit has been taken over, which eliminated it from the AREA. It also points out that there is no hard evidence of it (tracks or carcasses) in THAT region.

Therefore, our tiger is extinct.

Well, wait just a minute. Does our tiger have to be extinct just because of habitat takeover in one area and lack of hard evidence of it in that area? What if our tiger isn’t extinct? What if it just relocated to another area, and no longer lives in the region in question?

In order for the conclusion that our tiger is in fact extinct to be deemed even possible, you would first have to know that it didn’t relocate someplace else. That makes this idea a necessary condition of the argument, because it is necessary to know first that the tiger did NOT relocate and survive elsewhere in order for it to be POSSIBLE to CONCLUDE that it IS extinct. If it did just relocate and survive elsewhere, the conclusion would be false. Therefore, that information (that it did not relocate) is a necessary assumption imbedded within the argument.

Our correct answer choice is D, and it matches our prediction from above (we need to know that they DIDN’T relocate and survive someplace else) pretty well!


Now, let’s take a look at the answer choice you mentioned (A) and see what’s wrong.

A) Okay, so we DO need to assume that the tigers did NOT survive by some other means. However, we do NOT need to assume that those means were specifically sheep farming causing loss of habitat, driving the last few tigers to starvation. By singling out one very specific way in which they might not have survived (starvation), we are unjustifiably ruling out OTHER means by which they might not have survived. For example, it’s also necessary to assume that magical aliens did NOT come down from the sky and give our Tasmanian tigers special powers that allowed them to roam around completely undetected and unbothered by sheep. When you say that aliens did NOT get involved, you are NOT ruling out any other possible means by which the tigers might not have survived. Instead, with the aliens example you are simply saying that it’s necessary to assume that this one POSSIBLE reason WASN’T at play. Which is necessary to the conclusion too! There are countless necessary assumptions to any given argument. You can make them up out of thin air, like I did here! Yes, for the conclusion that the tigers are extinct to be possible, it is necessary to know that aliens did NOT save the tigers. It is also necessary to know that the tigers did NOT relocate elsewhere. However, answer choice A saying that it was NECESSARILY LOSS of HABITAT that drove the LAST FEW tigers to STARVATION is not leaving room for other possible alternatives (such as the alien friends) which could also be responsible for the extinction of the tigers if the conclusion is true. Therefore, answer choice A is overly restrictive. Saying it WAS one specific thing at play is a lot more restricting that saying it WASN’T one specific thing at play, and that is why answer choice A is not NECESSARY to the argument.

Hope this helps. I know necessary assumptions can be tricky to get the hang of, but one you start to see that necessary is unique because of the low standard it represents (it’s the bare minimum you need to know for a conclusion to at least be possible) you’ll get knocking them out in no time!

Feel free to follow up if you have anymore questions!