I would like to know if the following expressions can be used interchangeably.

just in case/out of caution/for caution’s sake/for the sake of caution/ err on the side of caution.

a. I took an umbrella just in case.

b. I took an umbrella out of caution.

c. I took an umbrella just for caution’s sake.

d. I took an umbrella just for the sake of caution.

e. I erred on the side of caution and took an umbrella.


  • 1
    I'd say "a" is definitely correct. I don't think caution is appropriate here. Caution is more likely if there is an aspect of danger. I find b,c,d and e very strange.
    – anouk
    Dec 22, 2019 at 22:07

3 Answers 3


I largely agree with GrammarBoy's own answer (i.e., they all work), but would add a few comments:

  1. The "caution" phrases imply a larger impact if something goes wrong, and also (to me) imply a more thought-out decision. "Just in case" is used for more casual decisions, or for situations where the risk is low.
  2. As mentioned elsewhere, "just for caution's sake" and "just for the sake of caution" sound strange and overly wordy to me.
  3. "I erred on the side of caution" is to call more attention to the decision process, and less to the actual decision itself.

Caveat: I'm American; British English tends to have different connotations.


I emailed Charles Harington Elster, the author of numerous books on the English language, and Kathy Watson, who is also known as the Ruthless Editor. They both said that all the choices are fine, but Mr. Elster added that [ for the sake of caution] and [ for caution’s sake] sound stilted, but not wrong.


These choices are grammatical and interchangeable.

But the point is that the choice (a) is the most common and natural. There are some other phrases that are more common than the other alternatives expressed in the question presented, for example:

as a precaution, for caution, in case of rain or in case it rains (if you want to protect yourself from rain).

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