On 11 Jun 2013, at 18:28, meekerdb wrote:

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On 6/11/2013 12:51 AM, Bruno Marchal wrote:On 10 Jun 2013, at 20:04, meekerdb wrote:Not one you can prove from arithmetic or logic. But the pointwas that true propositions, like "Flying pink elephants arepink" don't imply the existence of anything; just like "17 isprime" 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 logicalformula:if x is an elephant which is pink and which is flying then x ispink.This does not entail Ex( x = an elephant which is pink and whichis flying)For the same reason that:"if x is a prime number, which is even, and bigger that 3" then xis 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 andbigger than three". Then, if y anything; in classical logiceverything follows from a contradiction. But we were talkingabout the metalogical relation of true/false and fictional/real.I don't think two are parallel. It's true that 17 is prime - butit doesn't follow that 17 is real. It's true that Sherlock Holmeslived on Baker Street, but it doesn't follow that he existed.The difference comes from the fact that in arithmetic e can proveEx(x = 17), but we cannot prove in your "theory" that Ex(= SherlockHolmes).But "E" in those two propositions don't have the same meaning. Inthe first it means that the axioms of arithmetic imply there is anx=17. In the second it means there was person who had all or mostof the characteristics described in Conan Doyle's stories.

`It has the same meaning in different theories. Without giving me your`

`theory of humans, "Ex(x = Sherlock" has no meaning, except referring`

`to consensual reality, but this is what we want to explain. You beg`

`the question. In consensual reality it is just reasonable to say that`

`Sherlock does exist only as a fictional character. But that is not`

`what we discuss.`

`In the comp TOE Ex (x = sherlock) is as false as Ex (x = Brent),`

`because Brent and Sherlock are (different probably) sort of emerging`

`reality. Only natural numbers exist in the sense of "ExP(x)". So in`

`the comp TOE, only numbers are NOT fiction, if basic existence is the`

`criteria. Brent and Sherlock are different type of fiction.`

Of course something described by a contradiction can't exist. Buta contradiction is dependent on an axiomatic system. So a pinkelephant doesn't exist, but "There is a pink elephant." is not acontradiction; it's just a falsehood and it's not the case thateverything follows from a falsehood.It is the case that everything follows from a falsehood. (0=1) doesimplies everything.In classical logic. But logic is just supposed to formalize goodreasoning.

`Classical logic formalizes machines or numbers understanding of`

`Platonia.`

"There is a pink elephant." may mean no more than "That looks likean elephant painted pink." It's not an axiom of a formal system. Ideliberately included "flying" because it makes the identificationas "elephant" problematic. If we found an animal that looks like anelephant painted pink, we'd certainly call it a "pink elephant".But if we found an animal that looked like an elephant with wingsthat could fly, we'd only call it a "flying elephant" metaphorically.

`My problem was just with fictionalism in math. It is fake sort of`

`philosophy. We must avoid words like "real" or "fiction", just agree`

`on which theory we are willing to use.`

Bruno

Brentf -> q is a tautology. It is equivalent with ~f V p. that is with tV q."p -> everything" in all words where p is false, even if there areworlds were p is true.--You received this message because you are subscribed to the GoogleGroups "Everything List" group.To unsubscribe from this group and stop receiving emails from it,send an email to everything-list+unsubscr...@googlegroups.com.To post to this group, send email to everything-list@googlegroups.com.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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list?hl=en. For more options, visit https://groups.google.com/groups/opt_out.