{"id":2290,"date":"2021-12-13T14:43:05","date_gmt":"2021-12-13T14:43:05","guid":{"rendered":"https:\/\/maverickphilosopher.blog\/index.php\/2021\/12\/13\/questions-about-a-lukasiewicz-passage\/"},"modified":"2021-12-13T14:43:05","modified_gmt":"2021-12-13T14:43:05","slug":"questions-about-a-lukasiewicz-passage","status":"publish","type":"post","link":"https:\/\/maverickphilosopher.blog\/index.php\/2021\/12\/13\/questions-about-a-lukasiewicz-passage\/","title":{"rendered":"Questions about a Lukasiewicz Passage"},"content":{"rendered":"

E. B. sent this:<\/span><\/p>\n

\n

http:\/\/www.logicmuseum.com\/wiki\/Logical_form_(Lukasiewicz)<\/a><\/span><\/p>\n

\u201cWhen, for instance, asserting the implication 'If all philosophers are men, then all philosophers are mortal' you would also assert as second premiss the sentence 'Every philosopher is a man', you could not get from these premisses the conclusion 'All philosophers are mortal', because you would have no guarantee that the sentence 'Every philosopher is a man' represents the same thought as the sentence 'All philosophers are men'. It would be necessary to confirm by means of a definition that 'Every A is B' means the same as 'All A's are B's'; on the ground of this definition replace the sentence 'Every philosopher is a man' by the sentence 'All philosophers are men', and only then will it be possible to get the conclusion. By this example you can easily comprehend the meaning of formalism. Formalism requires that exactly the same thought should always be expressed by means of exactly the same series of words ordered in exactly the same manner<\/em>.\u201d<\/span><\/p>\n

My emphasis.<\/span><\/p>\n<\/blockquote>\n

Suppose we compare the following two argument displays:<\/span><\/span><\/p>\n

\n

If all philosophers are men, then all philosophers are mortal
All philosophers are men
—-
All philosophers are mortal.<\/p>\n

<\/span><\/p>\n

If every philosopher is a man, then all philosophers are mortal
All philosophers are men
—-
All philosophers are mortal.<\/span><\/p>\n<\/blockquote>\n

Are they both valid, or is only the first valid? Lukasiewicz is telling us in effect that only the first is valid. No doubt the first is<\/em> valid: it instantiates the valid argument form, modus ponendo ponens<\/em>.  But then, by my lights, so does the second. So both arguments are valid.<\/span><\/p>\n

But it all depends on what we take an argument to be.  I hold that  an argument is not the same as an argument display. A necessary but not sufficient condition of anything's being an argument is that it be a sequence of propositions<\/em>. A proposition is not the same as a sentence in the indicative mood. Die Sonne scheint<\/em> and 'The sun shines' are two different indicative sentence tokens in two different  languages. And yet they 'say the same thing' or rather can be used by the same or different speakers to  say the same thing. We accommodate this fact by introducing a species of abstract object we call propositions<\/em> or thoughts, the latter word used by L. above.  The sentences cited express one and the same proposition<\/em> or thought.  Similarly with 'All philosophers are men' and 'Every man is a philosopher.' They express the same proposition.<\/span><\/p>\n

So above what we have are two different ways of displaying one and the same argument.  Since that argument instantiates a valid argument form, the argument is valid.<\/span><\/p>\n

Consider now these two argument displays:<\/span><\/p>\n

\n

Omnis homo mortalis est
Sokrates homo est
——-
Sockrates mortalis est.<\/span><\/p>\n

Every man is mortal
Socrates is a man
—–
Socrates is mortal.<\/span><\/p>\n<\/blockquote>\n

How many arguments? One or two? One. One and the same argument is expressed in two different languages.  I conclude that an argument is not the same a collection of sentences. Sentences are physical (marks on paper, pixels on a screen, acoustic disturbances); propositions are not. They are not seen with the eyes or heard with the ears or felt (as in Braille) with the fingers; they are understood by the mind. <\/span><\/p>\n

Finally, <\/span>L. speaks of  exactly the same series of words ordered in exactly the same manner. <\/em> Same words in the same order? But how do we know that the words are the same? Is it because they have the same letters in the same order?  By that criterion, 'war' in the following two sentences is the same word:<\/span><\/p>\n

\n

Ich war ein Soldat.
I went to war.<\/span><\/p>\n<\/blockquote>\n

But the two series of letters in the same order are not the same word. <\/span><\/p>\n

Now consider this array:<\/span><\/span><\/p>\n

\n

All philosophers are men.
Philosophers are, all of them, men.
Every philosopher is a man.<\/span><\/span><\/p>\n<\/blockquote>\n

These sentences 'say the same thing,' i.e., they express the same proposition or thought. I know that because I understand English.  To understand English is to understand the meanings<\/em> of English words and sentences.  Meanings are understood by the mind not perceived by the sense organs.<\/span><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

E. B. sent this: http:\/\/www.logicmuseum.com\/wiki\/Logical_form_(Lukasiewicz) \u201cWhen, for instance, asserting the implication 'If all philosophers are men, then all philosophers are mortal' you would also assert as second premiss the sentence 'Every philosopher is a man', you could not get from these premisses the conclusion 'All philosophers are mortal', because you would have no guarantee that … Continue reading “Questions about a Lukasiewicz Passage”<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[108],"tags":[],"class_list":["post-2290","post","type-post","status-publish","format-standard","hentry","category-logica-docens"],"_links":{"self":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts\/2290","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/comments?post=2290"}],"version-history":[{"count":0,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts\/2290\/revisions"}],"wp:attachment":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/media?parent=2290"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/categories?post=2290"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/tags?post=2290"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}