What is the difference between "sum" and "existo" verbs? Would "Cogito, ergo sum" be equivalent to "Cogito, ergo existō"?

  • Welcome to the site, and very interesting question! But I'm afraid the answer has more to do with the philosophical meaning of to be (and the distinction made between being and existence) rather than with Latin language.
    – Rafael
    Aug 20, 2017 at 23:18
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    @Rafael I don't really think this question is purely philosophical. They could be asking whether or not one can substitute existo in where sum is used, and vice-versa (i.e. are the definitions similar enough where they can be interchanged, or do they have different connotations).
    – Sam K
    Aug 20, 2017 at 23:36
  • Agreed. The cogito ergo sum only makes philosophy more likely to be involved. Let's see what the OP has to say. Note that in philosophical terms the parallel sum/existo is the same as English to be/exist. I don't know if a more general context (classical Latin or daily English usage) gives additional insights
    – Rafael
    Aug 21, 2017 at 1:04

1 Answer 1


All the classical Latin dictionaries (Lewis and Short etc etc) I have consulted treat existo and exsisto as alternative forms, with two main meanings. The first is to step or come out, emerge, appear, often but not always used with the nuance of originating or arising. The second - an extension of the first meaning - is to be visible: to exist with the nuance of being discernible. Most of the citations given for the use of the word in this second sense are from Cicero and the implication for me is that "existo" had a narrower (and perhaps more learned) range of use.

Sum would be, I think, the more normal way of translating I am; existo would appear to emphasise coming into being or being manifest.

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