[Bups-dis] Question on the Conditionals

[Tim Short]

Josh -

I can't quite see your notation because of a formatting or font problem, 
but it looks like you are saying the following.  Apologies if I have 
misrepresented you.

You say that the sentence (IF P THEN Q) is true if P is false because 
that is how the truth table for the sentence works.  That's fine.  Then 
you point out that (IF P THEN NOT Q) is also true for the same reason if 
P is false.  That's also fine.

Then you say that you have a contradiction and this is where I think the 
problem is.  I guess the issue is that if both of these sentences are 
true and P is false, then Q must be true and so must NOT Q.  That isn't 
the case though because (IF P THEN Q) is still true as a sentence when Q 
is false.

Is this what you were getting at...?

josh seigal wrote:
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> I've noticed a not completely unrelated problem for the analysis of counterfactual conditionals (a problem for which, I am sure, there is a very easy solution).
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> The (putative) problem is this: a counterfactual is a subjunctive conditional where the falsity of the antecedent is assumed. However, it seems to me that, if this is the case, contradictions can easily be generated.
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> For example, take the counterfactual conditional (p É q). Using the above definition of counterfactuals, and the standard truth-conditions for conditionals, this comes out as true, since it antecedent, being counterfactual (ie contrary to fact) is false. However, this generates a problem when we notice that the counterfactual conditional (p É Øq), for the same reasons, also comes out true, hence yielding a contradiction.
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> As I’ve said, I’m sure there is a very easy way around this, and I’m sure it is no more than a superficial difficulty. It is just something I noticed when studying first-year logic and it is something that I haven’t got round to investigating further.> From: andrew.bacon at philosophy.ox.ac.uk> Date: Fri, 1 Aug 2008 17:18:38 +0100> To: rezakhs at yahoo.com> CC: bups-dis at bups.org> Subject: Re: [Bups-dis] Question on the Conditionals> > To reply to this message or start a new topic please email: BUPS-DIS at bups.org> -> > Hi Reza,> > > (if (P AND Q), then R), logically entails ( (if P, then R) OR (if Q, then R))> > One thing to note is that it's not clear that this *is* a logical entailment. We> should not confuse the above, which seems to be schematic for an inference form> couched in English, with the following, which is a logical entailment:> > > ((P & Q) -> R), logically entails ( (P -> R) \/ (Q -> R))> > One reason that first inference might fail is that if the English conditional> goes by a Stalnaker semantics, then it is not valid. What is possibly more> striking is that, if we go by a possible world semantics for conditionals, it is> no longer clear that "if ..., then ..." is a logical constant! It will depend on> the criteria of logicality for modal connectives.> > Also worth noting that the Stalnaker semantics appears to get the right verdict> for both your examples. We might just take this as a point for Stalnaker over> the material conditional analysis.> > Andrew> > > > > > > But there are dozens of examples which make trouble for this inference. E.g.:> > > > P: Diego is Jim's father> > Q: Mary is Jim's mother> > R: Diego and Mary are Jim's parents> > > > or may be a better one:> > > > P: I call her by her first name> > Q: I call her by her last name> > R: She loves it!> > > > The translation of the sentence at the left side does not match with the> equivalent sentence at the right side:> > > > For the first example, one might say it's a possible world conditional. (well> then try it with P: Plato is a fool. Q: Quine is a fool. R: Russell is a> fool.... still I think what is meant in the left side is different from what is> meant in the right side). But let's see the second example which works better:> > > > At the left side, the sentence tries to say that "she loves it if I call her> by her full name", while the second side says "she loves it either I call her by> her first name or her last name". > > > > This seems to be a famous problem. I saw the problem just recently; but there> was nothing on the solutions. Many of similar examples seemed to me to be> indicative conditionals and yet they got this translational problem. Any idea on> what should I look in? :-)> > > > Best,> > Reza> > > > > > __________________________________________________________> > Not happy with your email address?.> > Get the one you really want - millions of new email addresses available now at> Yahoo! http://uk.docs.yahoo.com/ymail/new.html> > _______________________________________________> > > > -> > Browse or search the BUPS-DIS archives, or unsubscribe from the mailing list> at: http://www.bups.org/mailinglist.shtml> > -- > Andrew Bacon> New College> 07830048336> http://users.ox.ac.uk/~lady1900> > _______________________________________________> > -> Browse or search the BUPS-DIS archives, or unsubscribe from the mailing list at: http://www.bups.org/mailinglist.shtml
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