Must versus will in All the Companion Guide, page 38

[yo4561]

Hello hello!

The book talks about modal verbs and provides an incorrect example and correct example below:
-Incorrect: This plan ensures that action MUST be taken.
-Correct: This plan ensures that action WILL be taken.

The incorrect example sounds okay when I use my ear. I see the "must" as a call to action... the plan ensures that they MUST act.

I see that "will" also makes sense because "ensure" calls for something to definitely occur, but what exactly about the "must" is wrong? The sentences just seem to be saying different things ---> "must" is a call to action and "will" is a definite action?

Unfortunately, the explanation in the book does not explicitly explain this example besides the overall explanation for the category in that it is redundant or expressed in an awkward manner. Perhaps this explanation means that ensure already equates to must...making this redundant?

[esledge]

Unfortunately, the explanation in the book does not explicitly explain this example besides the overall explanation for the category in that it is redundant or expressed in an awkward manner. Perhaps this explanation means that ensure already equates to must...making this redundant?

Yep, I think this is the reason.

Correct: We MUST arrive at the airport two hours before our flight.
Correct: Our itinerary ensures that we WILL arrive at the airport two hours before our flight.
Wrong: Our itinerary ensures that we MUST arrive at the airport two hours before our flight.
Maybe correct: Lengthy security lines ensure that we MUST arrive at the airport two hours before our flight.

As for that last example, I was thinking "what would let you use ensure and must together?" Maybe if something else ensures that we must do an action. This is not a frequently tested distinction, though.

[JbhB682]

Hello hello!

The book talks about modal verbs and provides an incorrect example and correct example below:
-Incorrect: This plan ensures that action MUST be taken.
-Correct: This plan ensures that action WILL be taken.

I see that "will" also makes sense because "ensure" calls for something to definitely occur, but what exactly about the "must" is wrong? The sentences just seem to be saying different things ---> "must" is a call to action and "will" is a definite action?

Hi Emily - could you please go over why "will" is acceptable in the above sentence ?

I thought "Will" and "Must" were both redudant, because :
- Ensure implies 100 % certainity

Hence you dont need "Will" nor "Must" which imply 100 % certainity.

Please assist !

[esledge]

Hi Emily - could you please go over why "will" is acceptable in the above sentence ?

I thought "Will" and "Must" were both redudant, because :
- Ensure implies 100 % certainity

Hence you dont need "Will" nor "Must" which imply 100 % certainity.

I don't accept the idea that "will" implies 100% certainty. [Example: He said he will call on Tuesday. Will he? Maybe.] The primary purpose of "will" in the example is to put the action in the future on the timeline (future tense), which is not at all redundant with the role "ensure" is playing here.

Correct: This plan ensures that action will be taken.
The plan ensures (with certainty NOW) that action will be taken (in the FUTURE).

All the certainly actually comes from "ensures." The contrasting example below switches "ensures" to "hopes," removing the certainty even though we still have "will":
Correct: The secretary hopes that action will be taken.