{"id":3299,"date":"2010-02-13T02:19:49","date_gmt":"2010-02-13T10:19:49","guid":{"rendered":"http:\/\/www.oeconomist.com\/blogs\/daniel\/?p=3299"},"modified":"2020-11-05T02:16:45","modified_gmt":"2020-11-05T10:16:45","slug":"3299","status":"publish","type":"post","link":"https:\/\/www.oeconomist.com\/blogs\/daniel\/?p=3299","title":{"rendered":"Thoughts on Boolean <q>Laws of Thought<\/q>"},"content":{"rendered":"<p>I first encountered <q>symbolic<\/q> logic when I was a teenager.  Unfortunately, I had great trouble following the ostensible explanations that I encountered, and I didn't recognize that my perplexity was not because the underlying subject were intrinsically difficult for me, but because the explanations that I'd found simply weren't very well written.  Symbolic logic remained mysterious, and hence became intimidating.  And it wasn't clear what would be its peculiar virtue over logic expressed in natural language, with which I was quite able, so I didn't focus on it.  I was perhaps 16 years old before I picked-up any real understanding of any of it, and it wasn't until years after that before I became comfortable not simply with Boolean <em>expression<\/em> but with processing it as an <em>algebra<\/em>.<\/p> <p>But, by the time that I was pursuing a master's degree, it was often how I generated my work in economics or in mathematics, and at the <em>core<\/em> of how I presented the vast majority of that work, unless I were directed otherwise.  My notion of an ideal paper was and remains one with relatively little natural language.<\/p> <p>Partly I have that notion because I like the idea that people who know mathematics shouldn't have to learn or apply much more than minimal English to read a technical paper.  I have plenty of praise for English, but there are an awful lot of clever people who don't much know it.<\/p> <p>Partly I have that notion because it is easier to <em>demonstrate<\/em> logical <em>rigor<\/em> by using symbolic logic.  I want to emphasize that word <q>demonstrate<\/q> because it is possible to be <em>just<\/em> as logically rigorous while expressing oneself in natural language.  Natural language is just a <em>notation<\/em>; thinking that it is intrinsically less <em>rigorous<\/em> than one of the <q>symbolic<\/q> notations is like thinking that &#321;ukasiewicz Polish notation is less rigorous than infixing notation or <span style=\"font-style: italic ;\">vice versa<\/span>.  I'll admit that some people may be less inclined to various sorts of errors using one notation as opposed to another, but <em>which<\/em> notation will vary amongst these people.  However, other people don't necessarily <em>see<\/em> that rigor when natural language is used, and those who are inclined to be <em>obstinate<\/em> are more likely to exploit the lack of <em>simplicity<\/em> in natural language.<\/p> <p>But, while it may be more practicable to lay doubts to rest when an argument is presented in <q>symbolic<\/q> form, that doesn't mean that it will be <em>easy<\/em> for readers to follow whatever argument is being presented.  Conventional academic economists use a considerable amount of fairly high-level mathematics, but they tend to use natural language for the purely <em>logical<\/em> work.<span style=\"vertical-align: top ; font-size: smaller ;\">[1]<\/span>  And it seems that most of them are distinctly uncomfortable with extensive use of symbolic logic.  It's fairly rare to find it heavily used in a paper.  I've had baffled professors ask me to explain elementary logical transformations.  And, at least once, a fellow graduate student didn't come to me for help, for fear that I'd immediately start writing symbolic logic on the chalk-board. (And perhaps I would have done so, if not asked otherwise.)<\/p> <p>The stuff truly <em>isn't that hard<\/em>, at least when it comes to the sort of application that I make of it.  There is a tool-kit of a relatively few <em>simple<\/em> rules, some of them <em>beautiful<\/em>, which are used for the lion's share of the work.  And, mostly, I want to use this entry to high-light some of those tools, and some heuristics for their use.<\/p> <p>First, though, I want to mention a rule that I <em>don't<\/em> use. <img loading=\"lazy\" decoding=\"async\" src=\"wp-content\/uploads\/2010\/02\/identity.png\" width=\"41\" height=\"11\" alt=\"(A = A) for all A\" style=\"display: block ; border: 0 ; margin: 1em ; margin-left: auto ; margin-right: auto ;\" \/> This proposition, normally expressed in natural language as <q>A is A<\/q> and called <q>the Law of Identity<\/q>, is declared by various philosophers to be one of the three <em>Principles<\/em> of logic.  But I have no g_dd_mn'd idea what to <em>do<\/em> with it.  It's not that I would ever want to <em>violate<\/em> it; it's just that I literally don't see anything <em>use<\/em>ful to it.  Ayn Rand and many of those for whom she is preceptrix treat it as an essential <em>insight<\/em>, but I think that it's just a <em>dummy proposition<\/em>, telling me that any <span style=\"font-style: italic ;\">thing<\/span> can stand where that <span style=\"font-style: italic ;\">thing<\/span> can stand.<span style=\"vertical-align: top ; font-size: smaller ;\">[2]<\/span><\/p> <div style=\"text-align: center ; font-weight: bolder ;\"><a href=\"?page_id=3307#cut_point\">&#91;Read more.&#93;<\/a><\/div> <hr width=\"50%\" align=\"left\" \/> <p><span style=\"vertical-align: top ; font-size: smaller ;\">[1]<\/span> There's an <em>idiotic<\/em> notion amongst a great many mainstream economists that the Austrian School tradition is somehow <em>less rigorous<\/em> simply because some of its most significant members eschew overt mathematics in favor of logical deduction expressed in natural language.  But most of the mainstream is likewise not using <q>symbolic<\/q> <em>logic<\/em>; neither is <em>necessarily<\/em> being less rigorous than otherwise.  The <em>meaning<\/em> of variables with names such as <q><var>q<sub>t<\/sub><\/var><\/q> can be every bit as <em>muddled<\/em> as those called something such as <q>the quantity exchanged at this time<\/q>.  There are <em>good<\/em> reasons to object to the rather <em>wholesale<\/em> rejection of overt mathematics by many Austrian School economists, but <em>rigor<\/em> is not amongst the <em>good<\/em> reasons.<\/p> <p><span style=\"vertical-align: top ; font-size: smaller ;\">[2]<\/span> <a href=\"?page_id=3307#cut_point_2\" style=\"text-align: center ; font-weight: bolder ;\">&#91;Read more.&#93;<\/a><\/p>","protected":false},"excerpt":{"rendered":"I first encountered symbolic logic when I was a teenager. Unfortunately, I had great trouble following the ostensible explanations that I encountered, and I didn't recognize that my perplexity was not because the underlying subject were intrinsically difficult for me, but because the explanations that I'd found simply weren't very well written. Symbolic logic remained [&hellip;]","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":""},"categories":[6,36,720,5,4],"tags":[548,302,99],"class_list":["post-3299","post","type-post","status-publish","format-standard","hentry","category-commentary","category-economics","category-epistemology","category-personal","category-public","tag-austrian-school","tag-logic","tag-mathematics"],"_links":{"self":[{"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=\/wp\/v2\/posts\/3299","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3299"}],"version-history":[{"count":2,"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=\/wp\/v2\/posts\/3299\/revisions"}],"predecessor-version":[{"id":11463,"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=\/wp\/v2\/posts\/3299\/revisions\/11463"}],"wp:attachment":[{"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3299"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3299"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oeconomist.com\/blogs\/daniel\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3299"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}