39 Must vs Have to
Both Must and Have to belong to the group of auxiliary modal verbs. They are used to express strong obligation or the need to do something.
Structural differences between Must and Have To with the Affirmative, Negative and Interrogative forms:
| MUST | HAVE TO | |
| AFF. |
subject + must* + action. | subject + have to + action (“has” for the third person) |
| NEG. |
subject + must* + not + action. | subject + do + not+ have to + action (“does” for the third person) |
| INT. |
must* + subject + action + (?). | do + subject + have to + action + (?) (“does” for the third person) |
*The form is always the same, even for the third person.
Affirmative
- I must take notes. (I want to do it.)
- I have to pass my test. (Or I will fail.)
Negative
- You mustn’t look in a book. (You are not allowed.)
- You don’t have to be a volunteer. (You have choice: You can but it is not obligatory.)
Interrogative
- Must you study A level before B? (Is it obligatory at your workplace?)
- Do you have to enroll to the class every day? (Is it necessary for you?)
Must is used when we want to show that there are personal circumstances which make it obligatory and the speaker has decided that is necessary. Must shows a stronger obligation than Have to.
Have to is used when we want to show that somebody else has made it obligatory (it is the external circumstances that makes it so).
General differences in meaning:
- Must expresses strong obligation due to personal opinion or authority;
- Have to is used to show that there is an obligation imposed by external factors.
Differences in Negative form:
- Mustn’t usually expresses prohibition;
- Don’t have to usually expresses that something is not necessary to be done.
Have to and Must are two modal verbs which are used to express strong obligation or the need to do something.
| MUST | HAVE TO | |
| Affirmative | subject + must* + action. | subject + have to + action (“has” for the third person). |
| Negative | subject + must* + not + action. | subject + do + not+ have to + action (“does” for the third person). |
| Interrogative | must* + subject + action + (?). | do + subject + have to + action + (?) (“does” for the third person). |
They differ in meaning:
- Have to is generally used to show that there is an obligation imposed by external factors, whereas Must expresses strong obligation due to personal opinion or authority;
- Don’t have to usually expresses that something is not necessary to be done. Mustn’t usually expresses prohibition.
For example:
— “I have to write an essay for mythology class or I will fail the class.“= The subject is obliged to write an essay for mythology class (Mythology class = external factor).
— “I must write an essay for mythology class or I cannot get extra points.“= The subject is obliged to write an essay because of personal reasons.
Let’s revise this content within the [Form] section. Take a look at the [Example] section that shows its use within a context.