I would like to ask about two things

  1. Can both "while" and "when" be used with a gerund?
  2. Which one sounds better: "While ordering" or "when ordering" ?

    • While ordering a taxi, reliability is very important

    • When ordering a taxi, reliability is very important

    • When you order a taxi, reliability is very important

  • Both can be used, but they have slightly different meanings.'
    – Barmar
    Commented Jul 6, 2015 at 21:50
  • The examples are strange. If you mean 'When ordering a taxi, it is important to know how reliable the firm is', I'd use this version. // Ordering a taxi is here a punctive event (happening at a point, or what can be considered a point, in time), so 'while' is inappropriate. Contrast 'While ordering a taxi, I dropped my wallet down a grid' (here, the phoning has to be considered as an extended period, with the mishap now the punctive event). Commented Jul 6, 2015 at 22:19
  • Ok, correct me if I`m wrong but is what you are saying essentially that "while" should be used with verbs in their non-punctive meaning? Like "While building a house [extended time period / building seen as a process] many unfortunate events happened" On the contrary, using "when" calls for a verb in its punctive meaning. Like "When building a house [building seen as point in time, as a whole], many unfortunate accidents may happen". Am I following you here?
    – IGO
    Commented Jul 6, 2015 at 22:54
  • 1
    Are these gerunds? What year (approx) and whose inspiration changed them from being participles? Please.
    – Hugh
    Commented Jul 6, 2015 at 22:55
  • 1
    No, no. Not sarcastic at all, but grievously out of date. Before ordering a taxi, and after ordering a taxi the noun-verb follows a preposition and is a gerund. Waiting for a taxi, patience is needed. Or Waiting for a taxi I dropped my wallet, are I think both participles, even though the qualified noun is only explicit in the second. I genuinely don't know if conjunctions are currently treated as adverbs qualifying verbal adjectives (ptc) or are now sometimes categorised as prepositions taking objects (ger). I hope you and I find out
    – Hugh
    Commented Jul 6, 2015 at 23:27

2 Answers 2


I believe Hugh is quite right to question the taxonomy here as gerunds. Rather, they should be treated as dangling participles (no subject for "ordering") or as a strained ellipsis ("When [one is] ordering a taxi, etc.").

As for the difference between "when" and "while, I'd say that depends very much on context. If the statement is "gnomic" (i.e., trying to offer a generalization), the "when" connective is appropriate; but if the statement is circumstantial (that is, two acts will be directly correlated by time), "while" serves well.


I think "when ordering" is equivalent to "if ordering" -- "when" indicates only that in this context, multiple concepts or facts coexist.

In contrast, "while ordering" implies that a second activity will take place concurrently, as in, "while ordering he could not help but stare at her nose".

  • When has dictionary meanings that don't involve time at all; "if" is a likely one here.
    – Stuart F
    Commented Jul 5 at 8:48

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