Counterfactual Conditions

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Greg Nisbet

Oct 28, 2010, 3:51:21 PM10/28/10
I was skimming wikipedia while doing an econ problem set and came
across this thing.

"1.If Oswald did not shoot Kennedy, then someone else did.
2.If Oswald had not shot Kennedy, then someone else would have."

(1) is an indicative conditional
(2) is a counterfactual conditional

How does one encode each of those in Lojban? I can't figure it out.


Oct 28, 2010, 5:37:07 PM10/28/10
to lojban
> (1) is an indicative conditional
Expressed with the appropriate mu'i/ki'u/ri'a/bai/etc.

> (2) is a counterfactual conditional


If I understand it correctly, one necessitates the other in this

Where {.i ganai carvi gi mi bevri lo santa} says that I carry the
umbrella if it rains, {.i go carvi gi mi bevri lo santa} says that if
it rains, I bring my umbrella, and if I bring my umbrella, it rains.
(Feel free to correct me on this.)

Jorge Llambías

Oct 28, 2010, 6:13:43 PM10/28/10

The indicative conditional is the ordinary logical connective "ganai
... gi ...", so:

ganai la ozuyld na pu celcatra la kenedis gi lo drata be .obu cu ja'a go'i

In Lojban this is transparently equivalent to:

ga la ozuyld pu celcatra la kenedis gi lo drata be .obu cu go'i
"Either Oswald shot Kennedy or someone else did."

The counterfactual is a bit trickier. One way is:

va'o lo nu da'i la ozuyld na pu catra la kenedis kei lo drata be
.obu cu ja'a co'e
"Under the hypothetical conditions that Oswald had not shot
Kennedy, someone else would have."

mu'o mi'e xorxes

John E Clifford

Oct 28, 2010, 6:14:28 PM10/28/10
Nice, but your 2 is merely a (truth functional) biconditional, not a
counterfactual (non-truth functional) conditional. Counterfactual involve
moving into the subjunctive or setting up alternate worlds, not just mucking
aout with truth function in this one.


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Michael Turniansky

Nov 1, 2010, 1:51:50 PM11/1/10
  But I thought that precisely what da'i does?  (And remember, I'm not a linguist.  If I'm wrong, please explain this to me in baby terms)

John E Clifford

Nov 1, 2010, 3:41:13 PM11/1/10
You could probably get a good discussion going about what 'da'i' does, but the gist is that it sets up an alternate world (how alternate is a hard question and would be at the center of the discussion), differing at least in that the hypothesis that describes it is one false in this here world. Then you claim that, in that world, something else would be true.  And then, in a serious case, you have to convince others that it really would  be true over there.  (Maybe, thinking slightly more baby terms, I should say "an alternate history" since we are all familiar with that.).  Did I miss the 'da'i' in your examples?  I only recall your talking about 'ganai ... gi..." (truth functional if-then, false only when the antecedent (the 'ganai' part) is true and the consequent (after 'gi') false) and truth functional biconditional (true only if the two parts have the same truth value, both true or both false).  If we reduce case 2 to either one of these, the result is true, but uninterestingly so, since it results from the fact that both parts are in fact false (if you peal off all the subjunctive stuff).  You might as well say "If Oswald didn't shoot Kennedy, then I am Queen of the May" (I'm not).  Counterfactual conditionals are just a different breed from "ordinary" "if,,, then,,," (which we rarely, if ever, use). Most of our conditional sentences are at least forward looking -- so in a different world/time -- and explicitly counterfactual.  The priority of this odd conditional is a product of fallowing Logic, where it is everybody's favorite -- mainly because it behaves so well, unlike counterfactuals.

From: Michael Turniansky <>
Sent: Mon, November 1, 2010 12:51:50 PM
Subject: Re: [lojban] Re: Counterfactual Conditions

Michael Turniansky

Nov 1, 2010, 3:57:07 PM11/1/10
  I apologize.  You had responded to Lindar's post, not xorxes, like I thought. (since gmail's default is to hide the responded to text, I didn't realize that.)  Ignore my comment, then.
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