A friend and I are arguing about this.

Does vacillation imply a mind? Can a non-intelligent thing vacillate? In the context of video games my friend mentioned that his ping was vacillating. I argued that oscillate would be more appropriate in that context. Was his use of vacillate correct there?

I've only ever heard vacillate refer to a person unable to settle on a decision or course of action.

  • 2
    People vacillate, things oscillate. If you want to anthropomorphize then maybe you could say that a thing was vacillating.
    – Jim
    Mar 14, 2015 at 19:23
  • Have you ever seen a squirrel crossing a road? If they don't vacillate, then neither do people. Mar 14, 2015 at 20:35

3 Answers 3


The definition for "vacillate" on Merriam-Webster is: "to repeatedly change your opinions or desires."

That would seem to me to imply that, in common usage and outside some sort of personification, the vacillating thing at least has opinions and desires. As for whether that requires a mind... ask on Philosophy Stack Exchange :).

  • I saw that definition but there are other definitions that seem to allow for inanimate objects
    – Paarth
    Mar 14, 2015 at 22:26
  • Dictionary.com's 3rd definition is "to oscillate or fluctuate." TheFreeDictionary's second definition is "To change between one state and another; fluctuate"
    – Paarth
    Mar 14, 2015 at 22:27
  • I suppose you're right, but it seems to me that the connotative meaning of "vacillate" is different because of its connection to the definition I cited. If you allow words any reasonable flexibility of meaning, it is technically no more incorrect to say that something inanimate is vacillating than it is to say that a person's mind is oscillating between one choice and another, but the somewhat immaterial connotations of the former term and the more material connotations of the latter make the switch a bit awkward (or poetic, if that's what you're trying for). Mar 15, 2015 at 1:44

I would have no problem with that use of vacillate.

Definition 1a at M-w.com states:

to sway through lack of equilibrium

It is frequently used of people who cannot choose between possible options (indeed, other definitions do specifically mention "changing your opinion" and so forth), but it does not have to be used only for people; it makes perfect sense to include anything that is flipping back and forth, at unpredictable (but generally short) intervals, between 2 possible values.

Vacillate, oscillate, and fluctuate are listed as synonyms, but I would distinguish between them as follows:

Vacillate: to switch back and forth rapidly but unpredictably between two values

Oscillate: to move smoothly or regularly between two values

Fluctuate: to move randomly within a range of values

In no case is it required that any of them refer to a person.

In your particular case, I would expect that fluctuating was the best word to choose, as I find it unlikely that a ping time restricted itself to only two values, but it's within the realm of possibility that it was vacillating instead.


I would favor fluctuate to describe the ping in the computer game; that is, the ping moves in a given range rather than simply alternating two knowns.

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