## Posts Tagged ‘mathematics’

### Helmholtz's Zählen und Messen

Monday, 16 October 2017When I first encountered mention of Zählen und Messen, erkenntnisstheoretisch betrachtet [Numbering and Measuring, Epistemologically Considered] by Hermann [Ludwig Ferdinand] von Helmholtz, which sought to construct arithmetic on an empiricist foundation, I was interested. But for a very long while I did not act on that interest.

A few years ago, I learned of Zahl und Mass in der Ökonomik: Eine kritische Untersuchung der mathematischen Methode und der mathematischen Preistheorie (1893), by Andreas Heinrich Voigt, a early work on the mathematics of utility, and that it drew upon Helmholtz's Zählen und Messen, which impelled me to seek a copy of the latter to read. To my annoyance, I found that there was no English-language version of it freely available on-line. I decided to create one, but was distracted from the project by other matters. A few days ago, I recognized that my immediate circumstances were such that it might be a good time to return to the task.

I have produced a translation, Numbering and Measuring, Epistemologically Considered by Hermann von Helmholtz It is not much better than serviceable. I don't plan to return to the work, to refine the translation, except perhaps where some reader has suggested a clear improvement and I effect a transcription.

I have not inserted what criticisms I might make of this work into the document. Nor have I presented my thoughts on how Helmholtz's ostensible empiricism and Frege's logicism are not as far apart as might be thought.

### Thinking inside the Box

Sunday, 4 March 2012I recently finished reading A Budget of Paradoxes (1872) by Augustus de Morgan.

Now-a-days, we are most likely to encounter the word paradox

as referring to apparent truth that seems to fly in the face of reason, but its original sense, not so radical, was of a tenet opposed to received opinion. De Morgan uses it more specifically for such tenets when they go beyond mere heterodoxy. Subscribers to paradox are those typically viewed as *crackpot*, though de Morgan occasionally takes pains to explain that, in some cases, the paradoxical pot is quite sound, and it is the orthodox pot that will not hold water. None-the-less, most of the paradoxers

, as he calls them, proceed on an unsound basis (and he sometimes rhetorically loses sight of the exceptions).

A recurring topic in his book is attempt at quadrature of the circle. Most of us have heard of squaring the circle

, though far fewer know to just what it refers.

I guess that most students are now taught to think about geometry in terms of Cartesian coördinates,[1] but there's an approach, called constructive

, which concerns itself with what might be accomplished using nothing but a stylus, drawing surface, straight-edge, and compass. The equipment is assumed to be perfect: the stylus to have infinitesimal width; the surface to be perfectly planar, the straight-edge to be perfectly linear, and the pivot of the compass to stay exactly where placed. The user is assumed able to place the pivot of the compass exactly at any marked point and to open it to any other marked point; likewise, the user is assumed to be able to place the straight-edge exactly touching any one or two marked points. A marked point may be randomly placed, or constructed as the intersection of a line with a line, of an arc with an arc, or of an arc with a line. A line may be constructed by drawing along the straight-edge. An arc may be constructed by placing the compass on a marked point, opening it to touch another marked point, and then turning it. (Conceptually, these processes can be generalized into `n` dimensions.)

A classic problem of constructive geometry was to construct a square whose area was equal to that of a given circle. Now, if you think about it, you'll reälize that this problem is equivalent to arriving at the value of π; with a little more thought, you might see that to *construct* this square in a *finite* number of steps would be equivalent to finding a *rational* value for π. So, assuming that one is restricted to a finite number of steps, the problem is insoluable. It was shown to be so in the middle of the 18th Century, when it was demonstrated that π were irrational.

The demonstration not-with-standing, people continued to try to square the circle into de Morgan's day, and some of them fought in print with de Morgan. (One of them, a successful merchant, was able to self-publish repeatedly.) De Morgan tended to deal with them the way that I often deal with people who are not merely wrong but are arguing *foolishly* — he critiqued *the argument as such*, rather than attempting to walk them through a *proper* argument to some conclusion. I think that he did so for a number of reasons. First, bad argumentation is a deeper problem that mistaken conclusions, and de Morgan had greater concern to attack the former than the latter, in a manner that exhibited the defects to his readers. Second, some of these would-be squarers of the circle had been furnished with proper argumentation, but had just plowed-on, without attending to it. (Indeed, de Morgan notes that most paradoxers will not bother to familiarize themselves with the arguments for the systems that they seek to overthrow, let alone master those arguments.) Third, the standard proof that π is not rational is *tedious* to mount, and tedious to read.

But de Morgan, towards justifying attending as much as he does specifically to those who would square the circle, expresses a concern that they might gain a foothold within the social structure that allowed them to demand positions amongst the learnèd, and that they might thus undermine the advancement of useful knowledge.[2] And, with this concern in-mind, I wonder why I didn't, to my recollection, encounter de Morgan once mentioning that constructive quadrature of the circle would take *an infinite number of operations*; he certainly didn't *emphasize* this point. It seems to me that the vast majority of would-be squarers of the circle (and trisectors of the angle) simply don't see *how many* steps it would take; that their intuïtion fails them exactly *there*. And their *intuïtion* is an essential aspect of the problem; a large part of why the typical paradoxer will not expend the effort to learn the orthodox system is that he or she is convinced that his or her *intuïtion* has found a way *around* any need to do so. But sometimes a *lynch-pin* in the intuïtion may be pulled, causing the machine to be arrested, and the paradoxer to pause. Granted that this may not be as potentially edifying to the audience, but if one has real fear of the effects of paradoxers on scientific pursuit, then it is perhaps best to *reduce their number* by a low-cost conversion.

De Morgan's concern for the effect of these géomètres manqués might seem odd these days, though I presume that it was quite sincere. I've not even heard of an attempt in my life-time actually to square the circle[3] (though I'm sure that some could be found). I think that attempts have gone out of fashion for two reasons. First, a greater share of the population is exposed to the idea that π is irrational almost as soon as its very existence is reported to them. Second, *technology*, founded upon science, has got notably further along, and largely by using and thereby *vindicating* the mathematical notions that de Morgan was so concerned to protect *because* of their importance. To insist now that π is, say 3 1/8, as did some of the would-be circle-squarers of de Morgan's day, would be to insist that so much of what we *do* use is unusable.

[1] Cartesian coördinates are named for René Descartes (31 March 1596 – 11 February 1650) because they were invented by Nicole Oresme (c 1320 – 11 July 1382).

[2] Somewhat similarly, many people to-day are concerned that paradoxers not be allowed to influence palæobiology, climatology, or economics. But, whereäs de Morgan proposed to keep the *foolish* paradoxers of his day in-check by exhibiting the problems with their modes of reasoning, most of those concerned to protect to-day's orthodoxies in alleged science want to do so by methods of ostensibly wise *censorship* that in-practice excludes views for being unorthodox rather than for being genuinely *unreasonable*. When jurists and journalists propose to operationalize the definition of science

with the formula that science is what scientists do

— ie that science may be identified by the activity of those acknowledged by some social class to be scientists — actual *science* is being displaced by orthodoxy *as such*.

[3] Trisection of the angle is another matter. As a university undergraduate, I had a roommate who believed that one of his high-school classmates had worked-out how to do it.

### Puzzle: All in the Timing

Monday, 25 July 2011Assume that you have a perfect twelve-hour clock, with an hour hand and minute hand, each of which moves continuously.

At certain times of day, the minute hand and hour hand will be pointed in *exactly opposite* directions. The obvious case is that of six o'clock. What are the other times? (Specify your answers *precisely*, rather than rounding to the nearest minute or second.)

At certain times of day, the minute hand and hour hand will be pointed in *exactly* the *same* direction. The obvious case is that of twelve o'clock. What are the other times? (Again, specify your answers precisely.)

(The actual mathematics here is very simple. And the insight that would allow one to answer the first question should apply with very minor modification to the second one.)

### Ixerei

Saturday, 21 May 2011A previous entry quotes a foot-note from Austrian Marginalism and Mathematical Economics by Karl Menger; that foot-note is tied to a sentence that I found particularly striking.

### Thoughts on Boolean Laws of Thought

Saturday, 13 February 2010
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 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 *expression* but with processing it as an *algebra*.

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 *core* 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.

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.

Partly I have that notion because it is easier to *demonstrate* logical *rigor* by using symbolic logic. I want to emphasize that word demonstrate

because it is possible to be *just* as logically rigorous while expressing oneself in natural language. Natural language is just a *notation*; thinking that it is intrinsically less *rigorous* than one of the symbolic

notations is like thinking that Łukasiewicz Polish notation is less rigorous than infixing notation or vice versa. I'll admit that some people may be less inclined to various sorts of errors using one notation as opposed to another, but *which* notation will vary amongst these people. However, other people don't necessarily *see* that rigor when natural language is used, and those who are inclined to be *obstinate* are more likely to exploit the lack of *simplicity* in natural language.

But, while it may be more practicable to lay doubts to rest when an argument is presented in symbolic

form, that doesn't mean that it will be *easy* 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 *logical* work.[1] 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.)

The stuff truly *isn't that hard*, at least when it comes to the sort of application that I make of it. There is a tool-kit of a relatively few *simple* rules, some of them *beautiful*, 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.

First, though, I want to mention a rule that I *don't* use. This proposition, normally expressed in natural language as A is A

and called the Law of Identity

, is declared by various philosophers to be one of the three *Principles* of logic. But I have no g_dd_mn'd idea what to *do* with it. It's not that I would ever want to *violate* it; it's just that I literally don't see anything *use*ful to it. Ayn Rand and many of those for whom she is preceptrix treat it as an essential *insight*, but I think that it's just a *dummy proposition*, telling me that any thing can stand where that thing can stand.[2]

[1] There's an *idiotic* notion amongst a great many mainstream economists that the Austrian School tradition is somehow *less rigorous* 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 symbolic

*logic*; neither is *necessarily* being less rigorous than otherwise. The *meaning* of variables with names such as

can be every bit as `q _{t}`

*muddled*as those called something such as

the quantity exchanged at this time. There are

*good*reasons to object to the rather

*wholesale*rejection of overt mathematics by many Austrian School economists, but

*rigor*is not amongst the

*good*reasons.

[2] [Read more.]

### Irksome Declaration

Saturday, 20 June 2009In looking for an established notation for a particular sort of permutation, I have run across a large number of tutorials that declare that the notation and formula for a permutation

is

This claim complete confuses the concept of a permutation with the_{n}P_{r}=n! / (n-r)!

*count*of possible permutations. It's rather like saying that an American is 306,719,000.

### Exclamation Marks Were a Poor Notational Choice

Saturday, 22 March 2008So to-day we learned that when I am *very tired* I might leave the Woman of Interest a long rambling message about problems of combinatorial mathematics.

Combinatorial mathematics is, on the whole, extremely useful; but it is *deathly* dull. And, while its usefulness obtains *on the whole*, some problems — such as that about which I left my message — are *utterly unimportant*.

In other words, I rambled about boring, useless math.