Buridan on impetus

Belette's comment the other day, and my follow-up yesterday led me to a further search, and further frustration. Is the 1509 edition the only available edition of a historically important work by Buridan, where he introduces the modern conception of impetus? Yes and no. It turns out there is no newer edition than the one published in 1509 by Johannes Dullaert. It was reprinted by Minerva G.M.B.H. in Frankfurt in 1964 but that is merely a copy, and a quick search reveals that it is now unavailable. The Warburg (my usual flight to safety) does not stock it.

I did find a digitised version of the original edition on Gallica, and here is the very page – question 12 of book VIII on Aristotle's Physics - but that got me very irritated, as it is completely unreadable. If you try magnifying it, you see that the resolution is low, and also the greyscale is wrongly set and inconsistent. Some pages are nearly black, some are nearly white, nearly all are unreadable. A further irritation is the gimmick application that organises page-turning views making it look as though it were a real book. I used to work with the Digital Medievalist IT specialists, who would come up with stuff like magnifying glasses when you want to zoom the text, fancy banners and borders and so on, when the real need is for better photography, better access to collections, and better organisation of archives and so on.

I also found an old translation by J.J. Walsh, of part of question 12, and was awestruck by Buridan's insight and clear thinking. He notes, as I mentioned in the previous post, that a millwheel keeps rotating once in movement, even though there is no external force acting on it, and no air displaced. He also argues that if we sharpened a spear at both ends, instead of just the front end, it could still be hurled in the same way through the air. Yet how could the air maintain pressure at the sharpened back, when we all know that sharpness easily displaces air? And all this from the comfort of an armchair. He further notes that once a ship is in motion, it keeps moving for a while even when the current is against it, and even though the movement of the air is not from behind, but from the front*. All this is clear evidence that it is not the air that maintains the impetus of a moving object.

He even suggests a theory to explain all this. Noting that a thrown feather does not travel as far as a heavy metal ball, he suggests that the impetus of a body is in proportion to its weight (I don't know the Latin word translated by 'weight'). Thus the motion of a feather is soon halted by the resistance of the air, whereas the motion of a heavy ball is not. And he suggests that because there is no resistance in the heavenly space, God only needed to set the whole thing in motion once, when the universe was created, from which point it kept going by means of impetus. Which is absolutely bang on, no? (Except, possibly, for the part about God).

*I concede he may have had to leave the comfort of his chair to ascertain this.

Armchair science

Stephen Law has an excellent post here about why science is better done in armchairs, which has a connection with Belette's question about the philosophy of Jean Buridan

Imagine two balls, one heavier than the other, connected by a string. Drop this system of objects from the top of a tower. If we assume heavier objects do indeed fall faster than lighter ones (and conversely, lighter objects fall slower), the string will soon pull taut as the lighter ball drags on and slows the fall of the heavier ball. But the system considered as a whole is heavier than the heavy ball alone, and therefore should fall faster than the heavy ball on its own. So Aristotle’s theory, just like the claim that there exists a four-sided triangle, generates a contradiction. Galileo could establish that it is false from the comfort of his armchair.

Quite. Philosophers have always preferred the comfort of armchairs and a good book, perhaps scientists should try this too. And following up Belette's question about Buridan's theory of impetus, I looked this up too. Buridan (in the twelfth question of Subtilissimae Quaestiones super octo Physicorum libros Aristotelis) challenges Aristotle's theory of why, when we throw an object through the air, it does not come to an abrupt halt and does not come crashing to the ground, as Aristotle's theory says it should. Aristotle's daft explanation is that the air projected by the thrower somehow propels the object forward. Buridan puts forward a number of armchair objections to this, of which the nicest involves the motion of a millwheel. This keeps turning in a circle once put in motion, yet circular motion does not displace any air. And this was even before the invention of armchairs (although admittedly you would have had to have seen a millwheel in operation to make this argument, and thus armchairs while necessary are not sufficient).

I would love this to be in the Logic Museum but the only edition I can find is from 1509, and early printed books are generally resistant to scanning. Something for the summer break, perhaps.

Logic Museum ban lowered

Somewhat to my surprise, the ban on Logic Museum Wikipedia links has been removed. However, plenty of absurdity still remains. It now has a special page to itself here. This means that a special team of Wikipedians, none of whom has any expertise in medieval Latin, to my knowledge, has been assigned to monitor any links to the museum added by a 'non trusted' person, and delete them. So anyone who added a link to this question by Duns Scotus, "Whether a material substance is individual through its actual existence" is in danger of being banned.

The oddity is that this kind of censorship doesn't bother Wikipedians, even though they are extremely bothered by other kinds of censorship. Thus this article on the pornographer Luke Ford has a number of links to porn sites, and this user managed to upload more than 25,000 pictures of porn stars onto Wikipedia's image repository.

What's so dangerous about medieval Latin, that Wikipedia readers are not allowed to see it?

Natural and artificial languages

Belette makes a breathtaking comment here that deserves comment. 

I know about the difference between a pointer and the thing pointed to. I'm a software engineer. Its all a lot clearer in an artificial language; one day philosophers will realise that.

This is breathtaking both in its ignorance and (for that reason) in its arrogance.  For the entire history of Anglo-American philosophy since Frege in the 1880s and Russell in the 1900s onwards is about using the insights acquired from the development of the predicate calculus - mainly by Russell and Whitehead in Principia Mathematica - to address ancient philosophical problems.

Russell says "I remain convinced that obstinate addiction to ordinary language in our private thoughts is one of the main obstacles to progress in philosophy"*.    Russell's early work explored the idea that the misleading subject-predicate form of traditional Aristotelian logic was responsible for the pernicious defects of monism.  His theory of descriptions is intended to show that by using a formal language to analyse a problematic sentence like 'the king of France is bald', we can resolve an apparently intractable philosophical problem.  Following that, almost the entire program of Anglo-American analytic philosophy (AAA) is to address philosophical problems by analysing ambigous, vague statements expressed in ordinary language into precise, crisp, verifiable statements in some formal or artificial language. Obviously the distinction between 'pointer and thing pointed to', which is essential to Tarski's theory of truth, has a significant place in this program.

So what is it that philosophers are not realising? 

*Quoted in R.M. Sainsbury, "The Perfect Language", Russell, Routledge 1979, p.140

Wikipedia article feedback

I have just been looking at the Wikipedia rating system. You go to the bottom of an article and click 'view ratings' to see what the crowd thinks of its trustworthiness, objectivity, completeness and quality of writing.

First of all, I don't understand the distinction between 'trustworthy' and 'objective'. Could an article be rated as objective, but utterly untrustworthy?  Or lacking any kind of objectivity, but entirely trustworthy?  In any case, I can make little sense of the results, when picking on articles that I know are poorly written, incomplete and untrustworthy, but which the system rates as well-written, complete etc.

For example, I've commented on the Ockham article many times, e.g. here.  There are many errors and many omissions, and the quality of the writing essentially depends on your view of how easy it is to combine paragraphs from the Catholic Encyclopedia with paragraphs of drivel. How are the lay public supposed to judge on the completeness of coverage of a subject when the whole point of an encyclopedia is to inform them about it?  How can they judge its objectivity? I agree that they might be able to judge the quality of the writing, but even this stinker, which has a quality template slapped on it, doesn't score that badly.

Interestingly this one, on Roscellinus, which I can see is a combination of the Catholic Encyclopedia and Britannica 1911, scores worse on quality of writing than the awful ones above.  But it's quite well-written, although the style is somewhat antequated. Perhaps the reason is its use of much longer sentences and paragraphs.  Perhaps the 4chan generation prefers articles with short paragraphs and short sentences.  So perhaps we can blame the internet yet again, he says, sounding like an old fart aged 70 who reads the Daily Mail.

(I had a look at 4chan yesterday but that is a subject for another vituperative, old fart kind of post).

Spamming in medieval Latin

The discussion continues on Wikipedia about whether links to the Logic Museum constitutes 'spam' or not.  It descends into ever deeper levels of absurdity.  E.g. "There is not much spamming in Medieval Latin these days".  Very true.

I see also that the article on Ockham's magnificient Summa Logicae has now been protected against vandalism.  When Wikipedia goes wrong, it goes very very wrong.

Maverick and Belette on Frege

Back after a software-imposed break. While all this was going on, Maverick philosopher commented on my Frege post, gently supportive but questioning whether cognitive value or informational content can be had by such subsentential items as 'morning star' and 'evening star.' I think it can be had. We both agree the proposition "grass is green" has informational content. This content differs from the content of "grass is yellow". How? How does changing the word 'green' to the word 'yellow' change the informational content of the whole proposition? Surely because the informational value of the word 'green' is different from the informational value of the word 'yellow'. Thus the informational value of a term is precisely its contribution to the informational value of the whole sentence. Frege says somewhere that the same sense corresponds to the same word, and that is why language is useful. We could use a single sign for the whole proposition, as with a train signal (red = the track is closed, green = the track is clear), but he says that would not be very helpful, as we would have to devise a new sign for every different thought we wanted to express. So we split the thought up into parts, with a different sign corresponding to each part of the thought.  If we understand 'informational value' in this way - as the contribution to the informational value of a whole proposition, my argument is sound.

Cmmenting on the post back here, Belette wondered whether my argument was valid at all. I argued as follows.

(1) The sentence “the morning star is the evening star” has informational content.
(2) The sentence “the morning star is the morning star” does not have informational content.
(3) Therefore, the term “the morning star” does not have the same informational content as “the evening star”.

Belette says that ‘the morning star’ really means ‘Venus, at certain positions in its orbit’. I’ll alter this (because I’m not sure the morning/evening distinction is anything to do with the orbit of Venus, as opposed to the rotation of the earth on its axis) to ‘Venus as it is in the morning’. Perhaps I am not understanding him, but I think he means that this expression is something that has a referent in the morning, but at no other time. As the earth rotates and Venus appears to rise in the sky and disappear in the glow of the rising sun, the reference of the expression fails, and becomes non-existent. And as the sun ‘sets’, the referent of ‘Venus as it is in the evening’ comes into existence. Thus the referent of ‘Venus as it is in the morning’ only exists in the morning, and the referent of ‘Venus as it is in the evening’ only exists in the evening. Venus, of course, exists all the time.

But if that is true, the argument above is no longer sound. The sentence “the morning star is the evening star” actually means “Venus as it is in the morning is Venus as it is in the evening”. But this is always false, for if the term on the left has a referent, it must be morning, in which case the term on the right has no referent, and the identity statement is false. Conversely, in the evening, the left term has no referent, and the right term does. Or neither term has a referent, in which case there can be no identity either (identity being a relation between existing things). Hence the second premiss is false, on the assumption that a sentence which is false in virtue of its meaning contains no information.

I question whether ‘the morning star’ does mean that. Surely it is a description picking out a certain object by means of its visibility in the morning. It is not part of its meaning that the object must cease to exist once morning has passed. It may cease to exist, of course, just as the light in the fridge ceases to exist when we shut the door. But continuation or cessation of existence is not part of its meaning. (Perhaps it is different for ‘the prime minister of England’, but that is a different case, I think).

Blogger editor has broken - no more posts until resolved

23 Feb - upgraded to IE 8, all now seems to work.  More posts in the pipeline, sorry for the interruption in service.

Explaining 'the morning star'

Belete suggests here that the ‘Morning star’ example in the SEP article on intensional logic is not very well explained.
I’m not seeing that, but let me explain the it in my own terms, here. Assume you do not know much about astronomy, but you know how to identify the “morning star”, namely as the heavenly body that is visible in the East in the morning, and you also know how to identify the “evening star”, namely the heavenly body that is visible in West in the evening. Then you may assume these are different objects, and so, if I tell that the morning star is in fact the same object as the evening star, I have given you some useful information. I could go on to tell you that it is not a star at all, but a planet, in fact the planet Venus, which rises and sets with the sun because it is much closer to the sun than we are. But that is not relevant here. The point is that the sentence “the morning star is the evening star” is informative, it tells you something you could not have worked out from the meaning of the terms alone. By contrast “the morning star is the morning star” gives you no information at all. Given that you know what the morning star is, it is simply an expression of the principle of identity, A = A for all A, which presumably you knew, or would have assumed, already. Thus ‘the morning star’ and ‘the evening star’ have different informational content.

Summarising:

(1) The sentence “the morning star is the evening star” has informational content.
(2) The sentence “the morning star is the morning star” does not have informational content.
(3) Therefore, the term “the morning star” does not have the same informational content as “the evening star”.

What’s wrong with that? We might want to make a few extra assumptions to make it logically watertight. For example, to add the assumption that if all the component parts of two sentences have the same informational content, then the sentences themselves have the same informational content (the compositionality principle). But I don’t see what’s desperately wrong with it as it stands.

De dicto in Wikipedia

I'm glad to see that something may (possibly) be done about the current ban on links from Wikipedia to the Logic Museum. John Vandenberg, who is president of Wikimedia Australia, and who is slightly more sane and mature than the bunch of teenagers who run the place, has left a kind comment on the spam blacklist page, saying that "The Logic Museum is scholarly work, of exceptional quality and utility to Wikipedia".

Yes of course, John!  How else would readers of Wikipedia understand the use of Latin phrases like de dicto and de re?  I discussed this in an earlier post, but let's see what Wikipedia has to say about this important distinction.

De dicto and de re are two phrases used to mark important distinctions in intensional statements, associated with the intensional operators in many such statements. The distinctions are most recognized in philosophy of language and metaphysics.

The literal translation of the phrase "de dicto" is "of (the) word", whereas de re translates to "of (the) thing". The original meaning of the Latin locutions is useful for understanding the living meaning of the phrases, in the distinctions they mark. The distinction is best understood by examples of intensional contexts of which we will consider three: a context of thought, a context of desire, and a context of modality.

This is horrible. Note the article doesn't have any warning sign that something is wrong (to preempt a complaint that William made about the Maverick post yesterday.  It is a mixture of the horribly clumsy and the horribly wrong.  The plural 'important distinctions' is merely clumsy, given that there is just one distinction.  So is "The distinctions are most recognized in philosophy of language and metaphysics", although it is not clear whether recognised is meant, as though writers outside those subjects are aware of the distinction, but refuse to recognise it, or whether made is intended, in the sense that writers outside those areas simply aren't aware of the distinction at all.

But some of it is just wrong.  The standard use of the term 'intensional' qualifies not a statement but a context.   See e.g. the more useful SEP article on this.  And the distinction itself is a distinction in reading or sense, which the introduction does not explain properly. Thus there is a de re reading of a particular sentence, or a de dicto.  And the worst bit is the explanation of the Latin 'original meaning'.  'De dicto' does not mean 'of the word', as my previous post made clear, and as another excerpt from the Logic Museum, this time from the Summa Logicae of pseudo-Aquinas (my hasty translation) makes clear.  A dictum is what we now call a 'that clause', which Latin expresses by combining an accusative with an infinitive - Socratem currere - 'Socrates's running' or 'that Socrates runs'.  In Latin such a construction can be the subject of a sentence, as in Socratem currere est necesse, where 'that Socrates runs' is the subject, and 'is necessary' is the predicate. We can say the same in English, although it sounds a bit old-fashioned, such as in 'that snow is white is a well-known fact'. In no way does 'dictum' mean a word, as Wikipedia says, possibly confusing it with 'dictio' which can mean a word, or an expression. It literaly means 'about (de) what is said (dicto).

As for de re, 'of the thing' is slightly better, although res in has a much richer semantics than the plain English 'thing'.  It is sometimes translated as 'about reality' or 'about the reality'.  Note the two letters that begin the word 'reality', which is not a coincidence.

Here is the link to the Summa Logicae.  Don't try inserting it in Wikipedia: it will get you banned. Needless to say, Google returns the Wikipedia article first, on a search for de dicto.

Latin

English

Ad sciendum autem earum quantitatem, notandum quod quaedam sunt propositiones modales de dicto, ut, Socratem currere est necesse; in quibus scilicet dictum subiicitur, et modus praedicatur: et istae sunt vere modales, quia modus hic determinat verbum ratione compositionis, ut supra dictum est. Quaedam autem sunt modales de re, in quibus videlicet modus interponitur dicto, ut, Socratem necesse est currere: non enim modo est sensus, quod hoc dictum sit necessarium, scilicet Socratem currere; sed huius sensus est, quod in Socrate sit necessitas ad currendum.

Now for knowing about their [i.e. modal propositions'] quantity, it should be noted that some modal propositions are de dicto, such as "that Socrates runs is necessary", namely those in which the dictum [i.e. the clause "that Socrates runs"] is the subject and the mode [i.e. 'is necessary'] is the predicate, and these are truly modals, for the mode here determines the verb by reason of composition, as was said above.  And some are modals de re, namely in which the mode is interposed in dictum, e.g. "Socrates necessarily is running", for the sense is not now that the dictum is necessary, namely 'that Socrates runs', but the sense of it is that in Socrates there is 'necessity towards running'.

Should you trust Wikipedia?

Sounds like one of mine, but actually one of the Maverick's, over here.  Recommended, as always.

Contingent and necessary identity

Anthony asks what happens if we attach the sentence "Someone called Shakespeare wrote Macbeth" to a text containing a fragment such as

(*) There was [also] a man called ‘Shakespeare’ who lived in Stratford. Shakespeare was a shareholder of the Globe company

I argued in my previous post that indefinite terms act as ‘referential isolators’. They prevent back-reference to any term in an earlier sentence. What Anthony seems to be getting at here is that ‘wrote Macbeth’ seems to be a description that applies to the Shakespeare who was a shareholder of the Globe, and so we might infer an identity, and hence a reference, that is ruled out by the ‘isolator’ theory.

I don’t agree. Consider

(**) Someone called ‘Shakespeare’ wrote Macbeth. There was [also] a man called ‘Shakespeare’ who lived in Stratford. Shakespeare was a shareholder of the Globe company.

I say that the identity between the Stratford man and the Globe man follows from the truth of the second and third sentence, because we cannot understand the ‘Shakespeare’ of the third sentence without understanding that it refers back to the indefinite ‘a man called Shakespeare’. Hence the identity statement ‘The Stratford man was the shareholder of the Globe company’ is true in virtue of the meaning of the terms.

By contrast, the identity of the author of Macbeth and the Globe shareholder cannot be inferred as a logical consequence of the truth of discourse (**) above. It makes the identity highly probable, admittedly, but probability, even if almost absolutely certain, is not the same as logical certainty. This is because of the referential isolator of the second sentence. By contrast, if we change this to

(***) Someone called ‘Shakespeare’ wrote Macbeth. Shakespeare lived in Stratford. Shakespeare was a shareholder of the Globe company.

i.e. if we turn the isolator into a back-referring term, the statement ‘the author of Macbeth was the Globe shareholder' is now true in virtue of the meaning of the terms.

This resolves Wittgenstein's complaint about identity, Tractatus 5.5303 - "Roughly speaking, to say of two things that they are identical is nonsense, and to say of one thing that it is identical with itself is to say nothing at all.  To say that "X is identical with itself" is trivial, because 'itself' refers back to the subject of the sentence. Because of the grammar, we cannot place an isolator between 'itself' and 'X'.  When there is an isolator, as with (**) above, the identity ceases to be trivial. The identity sign therefore is an essential constituent of our language.

British library Wikipedian

I nearly commented on this but Andrew Orlowski got there first.

Referential isolators

The previous post gives the background. It is time to introduce the idea of ‘referential isolation’, which we can easily explicate by considering the difference between the following three sentences.

(1) There was a man called ‘Shakespeare’ who lived in Stratford. There was a man called ‘Shakespeare’ who was a shareholder of the Globe company.
(2) There was a man called ‘Shakespeare’ who lived in Stratford. Shakespeare was a shareholder of the Globe company.
(3) Shakespeare lived in Stratford. Shakespeare was a shareholder of the Globe company.

Discourse (1) is two separate and complete sentences. It is not part of the meaning of the two sentences that there was a person who lived in Stratford who was a shareholder of the Globe company, although it is part of their meaning that there was someone in Stratford, and that there was someone – possibly the same person, possibly a different person – who was part of the Globe company. Thus it is not part of the meaning of the second sentence that its subject, if there is one, is the same as or different from the subject of the first, nor that it is the same as or different from the subject of any previous sentence. The indefinite article is thus a referential isolator. It prohibits back-reference to any previous sentence.

By contrast discourse (2) is complete as a whole, but the second sentence is incomplete. That is because the definite article ‘the’ cannot be meaningful unless it identifies the subject of some preceding sentence – in this case, the immediately preceding sentence, the first. It forces us to look back in just the way that the indefinite article forces us not to look back, and so acts as the opposite of an isolator (a ‘conductor’, perhaps?). Yet the back reference comes to a halt at the first sentence, because the isolator (‘a man called Shakespeare’) is still in place. The two sentences are complete, and have the force of a single indefinite sentence. They tell us that some person lived in Stratford and belonged to the Globe, without telling us whether this person was the same as or different from the subject of any previous sentence.

Discourse (3) is incomplete both as single sentences and as a whole. That is because when attached to the larger text of which it is a fragment, it is capable of generating further implications that you won’t get from (2), or (1). If there is a preceding sentence saying ‘someone called Shakepeare wrote Macbeth’, then we can infer, when (3) follows it, that the author of Macbeth lived in Stratford, and was a shareholder of the Globe. The two sentences are a sort of live rail potentially connecting us an earlier part, or parts, of a larger discourse.

This all presumes two things, namely (a) that the discourse is ordered by prior and posterior sentence and (b) that all parts of the discourse are available ad audientem. This is true of any verbal discourse through the ordering of time of utterance. It is true of any written text where the order of reading is determined, and the text is securely bound together so that there are no missing pages, or worm-eaten parts, or any other form of corruption. It is true of hypertext containing fixed and ordered links. It is not true of corrupt texts such as manuscripts, or where the text is complete but with the pages wrongly bound. It is not true of a newspaper where the articles are not supposed to be read in any particular order. It is not true of news media in general, where even if there is ordering there is no guarantee that the audience has received all the elements of the ordering (for example, he or she has missed the 9 o’clock news).

The question of how reference operates in the case of disordered and incomplete texts will be the next topic for discussion.

Someone white was going to dispute

The rest of the sophismata by Heytesbury are now available in the Logic Museum here, which reminds me of an old post in Beyond Necessity about the medieval sophism Album fuit disputaturum. The sophism is summarised in that post, and there are now two versions of it in the Logic Museum. One by Heytesbury himself, and the other written about 90 years earlier around 1250 by an unknown Parisian scholar.

I have a third version which I am currently transcribing from the manuscript known as Worcester 13, probably written about 1270, which I may publish in the Logic Museum when it is more or less ready.

Semantic completeness and singular terms

In my last post I distinguished between terms of which you would learn as part of a general requirement to communicate with others, and terms that you would need for specialist communication.  The former you would find in any standard or pocket dictionary,  the latter in a specialist work according to subject (a medical dictionary, a glossary of advanced mathematical terms etc).

The purpose of doing this was to avoid making any philosophical distinction such as between general terms (man') and singular terms ('Socrates').  General terms can occur in generalist ('man') and specialist ('acrocanthosaurus') reference books, and similarly for singular terms: the proper name 'London' is in my general dictionary, the name of individual Londoners in the London telephone book (think of a telephone book as a specialist dictionary of proper names), and the names of individual streets in the specialist 'A-Z of London' street directory.

I say that a discourse is 'semantically complete' in respect of any particular reference dictionary when it is syntactically well-formed, and when its meaning is clear to any person who has learned the meaning of terms found in the dictionary. 

I shall show that a discourse consisting of more than one sentence can be semantically complete, even when some of its component sentences are semantically incomplete. For example:

(1) A man and a boy were standing by a fountain.  The man had a drink.

Clearly the two sentences taken together are semantically complete. Any compact dictionary of English contains words such as 'a', 'man', 'boy' etc, and anyone who has learned the meaning of those words and understands basic English syntax will understand what the two sentences mean together.  So also the first sentence is complete.  Everyone who understands basic English understands "A man and a boy were standing by a fountain".  But the second sentence is not complete, at least not on its own.  You don't understand "the man had a drink" without reference to the first sentence, because without it, you don't understand that the two sentences together imply that a man who was standing by a fountain had a drink.  To understand the second sentence, you have to understand that 'the man' refers back to the man mentioned in the first sentence.  So it is not semantically complete, even though it is part of a discourse which is.

It is the same when we use proper names.

(2) A man called 'Dudley' and a boy were standing by a fountain. Dudley had a drink.

Even though the name 'Dudley', as it is used here, is not contained in any directory or dictionary of proper names, the meaning of the two sentences together is available to any competent speaker of English. For the name 'Dudley' is defined in the first sentence, and for that reason the second sentence is semantically incomplete.  It depends on the definition of the name given in the first sentence, and is not properly understandable without it.  Thus the 'reference' of the proper name 'Dudley' is really back-reference to a previous part of the text.

This conception of reference contrasts with the Kripkean conception of reference where the incomplete sense of a singular sentence must be completed by reference to the external world (not some prior text), and where the sense of a singular term must somehow be 'passed on' from speaker to hearer.  There is no need for reference to the external world, and there is no need for 'passing on' reference.  The reference of the name 'Dudley' in the second sentence is clear because of the semantic completeness of the two sentences together.  It is objectively clear, and does not need to be 'handed' from one person to another except in the sense that the speaker is able to construct a discourse that is clear to any competent hearer, and when the hearer is competent enough to understand it.

Competent users of a language

Yesterday I pondered whether we can make sense of 'competent user' of a language, given that we can never fully master any language.  There about 170,000 words in current use in the English language, of which I probably know about 15,000.  New words are being added every year.  In addition to that, there are billions of proper names whose meaning no single person has knowledge of. I'm assuming that French, German, Indian and Japanese proper names count, given that they, or some Anglicised version of them can meaningfully be used as part of an English sentence.

Is there any sense to the notion of 'competent user'?  Perhaps we should distinguish between 'competent use' of a language and 'specialist use'.  A specialist user will understand all or most of the terms connected with the specialism.  The specialism might be in medical terms, engineering or scientific or legal terms, in place names, historical figures.  Of course, nearly everyone is a "Facebook" specialist in the sense they know the names of  their friends - names whose meaning they know but probably 99.99% of the people on the planet do not.  A generalist user, by contrast, will be equipped to communicate using terms that are in general use.  It might be difficult to set a boundary for such generalist terms, but it would probably include all the words in the Shorter Oxford Dictionary, many proper names such as 'London', 'America', 'Caesar', 'Elizabeth II' and so on.

I will then define a discourse (i.e. a sentence or group of sentences) as 'semantically complete' when its meaning is clear to any generalist user of the language.

Semantic completeness

This morning I had the idea for the following loose definition. A discourse* 'semantically complete' when any competent user of the language can understand it, simply in virtue of understanding the language.

But this of course won't do.  I had meant to eliminate proper names, because understanding the language is not a requirement for understanding them.  But who is to say that  the process of learning new proper names (or new meanings for the same proper name) is not also a process of understanding the language?  I need a criterion for 'understanding the language' that rules out proper names, but I don't have one.

Is it that a certain perceptual acquaintance, or some relation with the external world is necessary in order to learn  a proper name?  Well perhaps, but that doesn't distinguish them from common names, because to learn the meaning of certain basic terms like 'red', 'round' and so on, we have to be acquainted with external reality.

*Discourse - a sentences or any group of sentences.

You are a donkey

New in the Logic Museum, fifteen Sophismata by the Oxford logician and mathematician William Heytesbury. Heytesbury also wrote a work proving that you are donkey (tu es asinus) in no fewer than 39 ways, called Sophismata Asinana. A sophisma is a statement where there are apparently reasonable arguments supporting both the statement and its denial. Resolving the sophisma involves close and careful attention to the meaning, possible ambiguities, and avoidance of fallacy. Latin only, for the moment.

The New York Times on the Wikipedia blackout

A nice piece here by Cary H. Sherman. It happens that he is chief executive of the Recording Industry Association of America, which represents music labels, so clearly a possible bias there. But he is fundamentally right about the problem of a very large website like Wikipedia which is exploiting its status as a supposedly neutral and independent to make a self-serving political point.  Platforms such as these have real power which is equal to, if not greater than the power of the traditional news carriers, as I argued earlier here.

Public restrooms in Bratislava

A real gem - read it before it gets deleted.

As of 2011, urinating or defecating in public in Slovakia is punishable by a fine of €33. The mistrust of public toilets, including at night when they are lit, is such that many prefer the toilets in fast food restaurants. Many restaurants and pubs lock their toilets and issue keys only upon demand by their customers. In spite of queues reminiscent of the days of socialism, there are no plans to build additional public restrooms in Bratislava.
The tourist industry is not happy with the situation, but the competition is that toilets are not perfect in other cities.

Every horse is living

Here is a translation of a question by Jean Buridan which has some affinity with our earlier discussion about men who are not men.  Reading what he says, it is clear that he would resolve our difficulty by rendering 'some men are not men' into 'some things which are men, are not men', which is clearly false.

Dici de omni

A new article in the Logic Museum on the dici de omni, a principle derived from Aristotle which was supposed by the medieval scholastic writers (such as Giles of Rome) to underlie all reasoning.  The article mentions the debased and inaccurate  version of the principle used by neo-scholastic writers and used in manuals of 'traditional logic' such as Mill's System of Logic.  It also mentions the current version of the Wikipedia article, which is seriously incomplete and inaccurate.  The irony, which I love, is that Wikipedia will be unable to link to the more comprehensive Logic Museum article because of the ban on all outward-bound links to the Logic Museum.  There is also a new category for 'dici de omni' so you can reference scholastic texts mentioning the principle, as well as a category for Wikipedia articles, linked from the Logic Museum, which need improvement.

Reasons for belief

There is a survey here being run by Duncan Colvin as part of his postgraduate research at Goldsmiths under the supervision of Prof Chris French, on why people believe or disbelieve certain things.  I tried but gave up at the first slide.  I had to indicate whether I believed or disbelieved creationism, and my top 3 reasons for believing or disbelieving it.  I thought straight away of the reasons scholastics might give for believing in the eternity or finitude of the world, constructed as three arguments for, three against, a long discussion for or against, followed by 'replies to the main arguments', and then realised any reply I gave in the little boxes on the survey would be sadly inadequate against such a standard.

Indexical facts and materialism

The Maverick as ever has come out with a characteristically challenging post here asking whether 'indexical facts' are a threat to materialism.  He concludes that they are.  More later, but I have a brief prologemena here. 

Meanwhile, some preliminary ideas from Buridan, in his fifth question on the first book of his Questions on the Prior Analytics.  What is signified by the expression 'for a man to drink wine'?  He lists out some opinions. According to some it signifies the the sentence (propositio) 'a man drinks wine'.  According to others, it is a sort of signifiable complex entity on the side of reality (a parte rei), corresponding to the proposition 'a man drinks wine'.  Others say that for a man to drink wine is simply the man as he is related in that way to wine.  Yet others say that it is a sort of accident inhering in the man as he is related in that way to wine. More later.

Ockham himself is not drinking wine, as he has an attack of the gout, due to his habit of slouching comfortably in the corner like an eighteenth century gentleman, squinting at the assembled company through a glass of red wine or port, passing trollish and mischievous comments.  This behaviour needs to stop, according to his wife.  Or he could obtain a gout stool, but unfortunately there is no Wikipedia article about it.