"It needs to {be / have been} deviated for 1 minute"


I would like to understand the difference between these two:

"It needs to have been deviated for 1 minute"
"It needs to be deviated for 1 minute"

Are both saying that the deviation needs to be occuring over time? I think that the past infinitive is just for that but on the other hand, wouldn't the other sentence mean the same?


Posted 2014-08-14T13:41:55.927

Reputation: 63

1It's not necessarily wrong, but this usage of transitive "to deviate [something]" is pretty unusual. Depending on the exact context, probably *divert* would be more suitable. – FumbleFingers Reinstate Monica – 2014-08-14T15:18:02.683

@Silkyss, is deviate in this sense some technical process, perhaps in Chemistry or Engineering? – Will Murphy – 2014-08-14T17:10:42.507

Yes, IT technical documentation. – Silkyss – 2014-08-14T17:19:04.600



Both of these expressions are ungrammatical. Deviate is an intransitive verb: it means to diverge from an appointed course or established value, not to cause something to diverge.

An intransitive verb cannot be cast in the passive voice. Consequently you must say:

It needs to have deviated for one minute. OR
It needs to deviate for one minute.

If these sentences define the circumstances under which some subsequent event is triggered, such as a correction or a warning message, there is no significant difference between them: both express the fact that action is taken after a one-minute deviation.

If this is not the case—for instance, if the deviation is actively desired in order to accomplish your purposes—then the distinction drawn by magistermurphy is operative: the sentence with the perfect construction looks to a point in time after the deviation, while the sentence with the simple construction looks to a point before the deviation.

StoneyB on hiatus

Posted 2014-08-14T13:41:55.927

Reputation: 176 469

THanks. But I think it can be cast in the passive voice like this: It needs to be deviated from the baseline ... Would that be correct? – Silkyss – 2014-08-14T15:28:07.443

@Silkyss No: only transitive verbs can be cast in the passive. You cannot deviate something, so something cannot be deviated. – StoneyB on hiatus – 2014-08-14T16:15:47.750

strange. The following sentence was written by a native speaker: .... has been deviating from the baseline long enough and activates the system. – Silkyss – 2014-08-14T16:29:38.027

@Silkyss That is not a passive construction, which is built with BE + *past participle* but a progressive construction, built with BE + *present participle* (-ing form). (Specifically, it is a present perfect progressive.) – StoneyB on hiatus – 2014-08-14T16:37:47.070

THank you very much. So even if the text is technical, I cannot say use "it needs to be deviated from ...", right – Silkyss – 2014-08-14T17:14:51.677

@Silkyss That is correct. We say that a value deviates from an established norm or standard, not that it "is deviated". You occasionally find a transitive use among 19th century scientists, but this use has not caught on and should be regarded as non-standard. – StoneyB on hiatus – 2014-08-14T18:57:26.457


The sentences do not mean the same thing. "It needs to be deviated for 1 minute" means that this is the next step, that it should be deviated now.

"It needs to have been deviated for 1 minute," means that it should already have happened. It means the same thing as, "Before the next step happens, the one minute of deviation must already be done."

Will Murphy

Posted 2014-08-14T13:41:55.927

Reputation: 755

Are you sure "It needs to have been deviated" is correct, grammatically? – Manish Giri – 2014-08-14T14:25:07.033

Yes. See here under "perfect infinitive: passive." http://www.grammaring.com/the-forms-of-the-infinitive

– Will Murphy – 2014-08-14T14:28:40.787

But deviate is intransitive and cannot be cast in the passive. – StoneyB on hiatus – 2014-08-14T16:46:22.463

That's true. I had assumed this was a technical use of deviated and that it could be used passively in that technical sense. If that is not the case, both expressions are ungrammatical, as @StoneyB said. – Will Murphy – 2014-08-14T17:01:22.070