Are these entirely interchangeable? Or is there sometimes reason to use one but not the other? (Other than, as one website says, to use 'eo ipso' rather than 'ipso facto' if you really want to be pretentious and obscure.)

Wiktionary says: 'eo ipso' = Through or by that very act or quality; thereby. 'ipso facto' = By that very fact itself.

I came across 'eo ipso' in this sentence:

It is one thing to say that I know what is good for X, while he himself does not; and even to ignore his wishes for its - and his - sake; and a very different one to say that he has eo ipso chosen it, not indeed consciously, not as he seems in everyday life, but in his role as a rational self which his empirical self may not know - the 'real' self which discerns the good, and cannot help choosing it once it is revealed.

  • The Wiktionary definition you mentioned is literal, but useless or even wrong. Try now: en.wiktionary.org/w/…
    – Nemo
    Nov 18, 2015 at 16:10

3 Answers 3


Ipso facto would not make sense in your example, as there is no 'fact' referred to. Eo ipso there means 'in or by himself', which does make sense with the qualification in the next clause.

Eo ipso is not a phrase to be recommended (unless you are writing abstruse philosophy, in which case you need a considerably greater command of the language than a website can help with); on the whole, I would avoid it praeter necessitatem.

  • Is the usage of "praeter necessitatem" in the last sentence even grammatically valid?
    – Pacerier
    Sep 24, 2014 at 13:03
  • 1
    @Pacerier To me, it looks grammatically valid, but it seems to mean that he would avoid it more than it needs to be avoided. ("I would avoid it beyond necessity.") May 5, 2016 at 22:24
  • 1
    praeter can also mean unless, not only beyond. So the phrase would be "I would avoid it unless necessary". And apart from that, I think the statement is meant ironically. Aug 9, 2017 at 7:55

I believe eo ipso and ipso facto are in general the same.

But there is a distinction: the former has a broader meaning; the latter is bound to 'a fact'. (And in law, each is contrasted, for instance, to 'ipso iure', and 'ex lege'.)


"Eo ipso", meaning "in itself", has a greater implication than "ipso facto". Eo ipso implies a state without external influence, as a noumenon. Ipso facto implies a state dependent on external influence, as a phenomenon. I'm using Kantian language here, because the concept of eo ipso is most obviously similar to the Kantian noumenon.

  • 1
    Welcome to Stack Exchange! Please could you improve this answer by adding some links and citations to support your claims? May 5, 2016 at 21:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.