On Wed, Jun 12, 2013 at 11:17 AM, Bruno Marchal <[email protected]> wrote: > > On 11 Jun 2013, at 23:18, John Mikes wrote: > > Laughing stock: how can so many excellently educted and smart(est) > scientists SERIOUSLY debate on farces like flying pink elephants? > > > > Those are test cases, extreme case, to argue more easily on the question of > existence, which is not obvious. > Of course we are not discussing on the existence of flying elephants at all.
Maybe on a smaller planet with less gravity or a denser atmosphere flying elephants would be a viable evolutionary niche? Telmo. > Bruno > > > > > JM > > On Tue, Jun 11, 2013 at 12:28 PM, meekerdb <[email protected]> wrote: >> >> On 6/11/2013 12:51 AM, Bruno Marchal wrote: >>> >>> >>> On 10 Jun 2013, at 20:04, meekerdb wrote: >>> >>>> On 6/10/2013 10:52 AM, Bruno Marchal wrote: >>>>> >>>>> >>>>> On 10 Jun 2013, at 18:25, meekerdb wrote: >>>>> >>>>>> On 6/10/2013 12:19 AM, Telmo Menezes wrote: >>>>>>> >>>>>>> On Sun, Jun 9, 2013 at 2:40 PM, Bruno Marchal <[email protected]> >>>>>>> wrote: >>>>>>>> >>>>>>>> On 09 Jun 2013, at 11:20, Telmo Menezes wrote: >>>>>>>> >>>>>>>>> On Sun, Jun 9, 2013 at 9:23 AM, Bruno Marchal <[email protected]> >>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On 08 Jun 2013, at 17:55, meekerdb wrote: >>>>>>>>>> >>>>>>>>>> On 6/8/2013 1:02 AM, Bruno Marchal wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On 08 Jun 2013, at 05:15, meekerdb wrote: >>>>>>>>>> >>>>>>>>>> On 6/7/2013 4:00 PM, Stephen Paul King wrote: >>>>>>>>>> >>>>>>>>>> Yes, if there was a text of this it would be nice... I found this: >>>>>>>>>> http://plato.stanford.edu/entries/fictionalism-mathematics/ >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> A fictionalist account holds that some things are fictional, i.e. >>>>>>>>>> don't >>>>>>>>>> exist even though their complete description is self-consistent. >>>>>>>>>> Everythingists apparently reject this idea. Platonists seem to >>>>>>>>>> equate >>>>>>>>>> 'true' with 'exists'. If you believe 17 is prime you must believe >>>>>>>>>> 17 >>>>>>>>>> exists. I think this is wrong. If you believe that a flying pink >>>>>>>>>> elephant >>>>>>>>>> is pink, must you believe a flying pink elephant exists? >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Flying pink elephants are pink and not pink. That's why flying >>>>>>>>>> pink >>>>>>>>>> elephant >>>>>>>>>> can't exist. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> A pink elephant is pink by construction. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Exact. But the flying pink elephant are also not pink. By logic. >>>>>>>>>> Or show >>>>>>>>>> me >>>>>>>>>> a flying pink elephant living on this planet which isn't not pink. >>>>>>>>> >>>>>>>>> >>>>>>>>> Bruno, how are flying pink elephants any different from things that >>>>>>>>> I >>>>>>>>> remember but am not experiencing this very moment? >>>>>>>> >>>>>>>> >>>>>>>> I add explanation. Here you describe two 1p events. They are >>>>>>>> similar, >>>>>>>> although I guess you don't have precise memory of having actually >>>>>>>> seen a >>>>>>>> Flying Pink Elephant in your life, except in cartoon or dreams. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>> For example, I've >>>>>>>>> been to Brussels but I'm not there right now. Brussels is an >>>>>>>>> abstraction in my mind, but I believe it's the capital of Belgium. >>>>>>>>> That's part of the Brussels abstraction, in the same sense that >>>>>>>>> being >>>>>>>>> pink is part of the flying pink elephant abstraction. No? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> I do not dispute that fact. Pink elephant are pink. >>>>>>>> >>>>>>>> But the pink elephant on this planet happens also to be brown >>>>>>>> rampant worms. >>>>>>>> And I'm afraid that is only a classical logician's joke. >>>>>>>> >>>>>>>> (x = Flying Pink Elephant) -> (x = Brown Rampant Worms) is true on >>>>>>>> this >>>>>>>> planet because (x = Flying Pink Elephant) is false for all x, on >>>>>>>> this planet >>>>>>>> (I think), >>>>>> >>>>>> >>>>>> >>>>>> But (x = Flying Pink Elephant) is false for all x, is an empirical >>>>>> proposition. >>>>> >>>>> >>>>> I agree. >>>>> >>>>> >>>>> >>>>> >>>>>> Not one you can prove from arithmetic or logic. But the point was >>>>>> that true propositions, like "Flying pink elephants are pink" don't imply >>>>>> the existence of anything; just like "17 is prime" doesn't imply the >>>>>> existence of 17. >>>>> >>>>> >>>>> But how do you formalize "flying pink elephant are pink" ? >>>>> >>>>> I am simpled minded, so I formalized it in a first order logical >>>>> formula: >>>>> >>>>> if x is an elephant which is pink and which is flying then x is pink. >>>>> >>>>> This does not entail Ex( x = an elephant which is pink and which is >>>>> flying) >>>>> >>>>> For the same reason that: >>>>> >>>>> "if x is a prime number, which is even, and bigger that 3" then x is >>>>> bigger than 3" >>>>> >>>>> does not entail Ex(x = even prime number bigger than 3). >>>> >>>> >>>> Actually it does. Let y="x is a prime number which is even and bigger >>>> than three". Then, if y anything; in classical logic everything follows >>>> from a contradiction. But we were talking about the metalogical relation >>>> of >>>> true/false and fictional/real. I don't think two are parallel. It's true >>>> that 17 is prime - but it doesn't follow that 17 is real. It's true that >>>> Sherlock Holmes lived on Baker Street, but it doesn't follow that he >>>> existed. >>> >>> >>> The difference comes from the fact that in arithmetic e can prove Ex(x = >>> 17), but we cannot prove in your "theory" that Ex(= Sherlock Holmes). >> >> >> But "E" in those two propositions don't have the same meaning. In the >> first it means that the axioms of arithmetic imply there is an x=17. In the >> second it means there was person who had all or most of the characteristics >> described in Conan Doyle's stories. >> >>> >>> >>> >>> >>> >>> >>>> Of course something described by a contradiction can't exist. But a >>>> contradiction is dependent on an axiomatic system. So a pink elephant >>>> doesn't exist, but "There is a pink elephant." is not a contradiction; it's >>>> just a falsehood and it's not the case that everything follows from a >>>> falsehood. >>> >>> >>> It is the case that everything follows from a falsehood. (0=1) does >>> implies everything. >> >> >> In classical logic. But logic is just supposed to formalize good >> reasoning. "There is a pink elephant." may mean no more than "That looks >> like an elephant painted pink." It's not an axiom of a formal system. I >> deliberately included "flying" because it makes the identification as >> "elephant" problematic. If we found an animal that looks like an elephant >> painted pink, we'd certainly call it a "pink elephant". But if we found an >> animal that looked like an elephant with wings that could fly, we'd only >> call it a "flying elephant" metaphorically. >> >> Brent >> >>> >>> f -> q is a tautology. It is equivalent with ~f V p. that is with t V q. >>> >>> "p -> everything" in all words where p is false, even if there are worlds >>> were p is true. >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Everything List" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/everything-list?hl=en. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/everything-list?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > > > > http://iridia.ulb.ac.be/~marchal/ > > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/everything-list?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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