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# "Unless" question

Member
edited September 2020 203 karma

When a sentence begins with "Unless", does the beginning of that sentence become the necessary condition, and you would then negate the second half of the sentence? #help

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## Comments

• Member
69 karma

So I'm just gonna make something up to (hopefully) help you out here...say we have the following:

Unless I finish my homework tomorrow, I will not go to the mall on Thursday.

I finish my homework tomorrow = A
I will not go to the mall on Thursday = B

We could rephrase this as the following:

I will not go to the mall on Thursday unless I finish my homework tomorrow.

In this case, I would negate everything before 'unless' (B), which is the sufficient condition, and everything after 'unless' is in the necessary.

Which gives us the following:

If I go to the mall on Thursday, then (this means) I will finish my homework tomorrow.

It helps to rearrange the sentence so the 'unless' is in the middle, but you could also just apply the negation technique when unless is in the beginning of the sentence. You would get the contrapositive, as follows, for the following statement (Unless I finish my homework tomorrow, I will not go to the mall on Thursday):

If I do not finish my homework tomorrow, then I will not go to the mall on Thursday.

which is the same as "If I go to the mall on Thursday, then I will have finished my homework tomorrow"

• Free Trial Member
25 karma

I totally agree with your example > @sassyloni said:

So I'm just gonna make something up to (hopefully) help you out here...say we have the following:

Unless I finish my homework tomorrow, I will not go to the mall on Thursday.

I finish my homework tomorrow = A
I will not go to the mall on Thursday = B

We could rephrase this as the following:

I will not go to the mall on Thursday unless I finish my homework tomorrow.

In this case, I would negate everything before 'unless' (B), which is the sufficient condition, and everything after 'unless' is in the necessary.

Which gives us the following:

If I go to the mall on Thursday, then (this means) I will finish my homework tomorrow.

It helps to rearrange the sentence so the 'unless' is in the middle, but you could also just apply the negation technique when unless is in the beginning of the sentence. You would get the contrapositive, as follows, for the following statement (Unless I finish my homework tomorrow, I will not go to the mall on Thursday):

If I do not finish my homework tomorrow, then I will not go to the mall on Thursday.

which is the same as "If I go to the mall on Thursday, then I will have finished my homework tomorrow"

I totally agree with your example its is helpful to understand how and where to use Unless.

• Member
edited September 2020 19 karma

i think you got it. if unless is the beginning of the sentence, then yes its in the necessary.

A unless B aka "unless B, then A" =
if not A, then B
if not B, then A

B unless A aka "unless A, then B" =

if not B, then A
if not A, then B

see how they are the same?
only the sufficient condition is negated.

• Member
203 karma

Thank you so much!!! This helped immensely.

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