# The author uses the word "immediacy" (line 39) most likely in order to express

txcwby on February 4, 2019

I am so lost

I am so lost on these. I have watched the video repeatedly and can grasp the concepts that are spoken about in the video about how to negotiate the sufficient and necessary conditions. However, during the homework flash cards I have yet to solve how the order is done. Can someone explain how they come up with the order? P: NC - NX X - C P: C: X - ND D - NX I solved this by laying the answer out as: d-nx -c so the answer I came up with for the second P: is NC - X. The answer that the card shows is D - NC. Can someone show me where I keep going wrong?

Replies

Ravi on February 4, 2019

@txcwby,

I'm not following which question on the homework/flashcards you're
referring to in your message. Could you let me know which question it
is? I know you wrote down some of it in your message, but I'm unable
to understand because I don't see any arrows in what you wrote. If you
could point me to the specific question you're referring to, I'd be

Thanks!

txcwby on February 5, 2019

sorry it is flash card 1 of 17 on missing premise drills

Ravi on February 9, 2019

@txcwby,

Thanks. I'm happy to go through this with you.

We have

P: not C - >not X
P:
C: X - >not D

not C - >not X can also be written as X - >C

The conclusion can also be written as D - >not X

P: not C - >not X (X - >C)
P:
C: X - >not D (D - >not X)

Notice that not D first appears in the conclusion. It helps for us to
also have the contrapositives for what we've been given because we
need to be able to see how we can link everything together to make a
conditional chain.

We have X - >C in the first premise and X - >not D in the conclusion.
How can we go from

X - ->C

and conclude X - >not D?

We need a link between C and not D

If we add C - >not D, then we have

X - >C

C - >not D

Conclusion: X - >not D since X - >C - >not D

Does this make sense? The key is to try and think of how you can make
everything fit into one nice, pretty chain so that the premises flow
directly to the conclusion.

Let us know if you have any other questions!