First, I am not a mathematician, and in fact for most of my life I've hated doing math despite my ever returning interest in its—to me—mystical operations and results. Since the days I had first encountered Plato's thoughts on numbers I had realized that mathematics must have a place in any grand philosophical system, it is a part of reality and our comprehension of it which could not be left out. Nonetheless, as an informal outsider to the arcane arts of mathematical formality I have long had a distaste for the posited character of mathematics as it is commonly taught, I have for a few years now been aware that what I really want to know is the what and the why of mathematical operations and results. It has been a goal in the back of my mind to eventually tackle this issue by going back to the roots of mathematics, to Euclid's geometry, and then moving up through the basic mathematics of arithmetic, perusing the various fundamental interpretations of the objects and operations of math. This book was an accidental read, I simply chanced upon it on a youtube video comment, but this has served the purpose of giving me some insight into these questions of the what and why of mathematics. It is a fascinating read, it is also an incredibly clear and easy read for anyone not well versed in mathematics, after all we're dealing with the most basic numbers and operations.
Imaginary numbers are strange and unintelligible—everyone knows and believes this when they first are introduced. How can we take the square root of a negative number? When we attempt to think of it in quantitative terms there is no possible meaning to the operation.
The source of the problem is an innocuous kind of number that we all simply take for granted nowadays, surely nobody thinks that *negative numbers (-n)* don't make sense. They are debts, quantities of lack, they are a smaller quantity than their positive counterparts, etc. I didn't think such numbers were problematic either. I had questioned why (- * - = +), why the - sign changed a + but a + didn't change a -. I wondered why in the world it made sense to take the square root of -1, but I never questioned what the + and - as operators really meant, and further I didn't question the meaning of the relation of the +numbers and -numbers.
This book brings to light the history of these negative numbers and their ground shattering consequences when the rules of traditional mathematics were extended to them in asymmetric ways to the +. The reasons for why (- * - = +) came both from purely formal yet unintelligible reasons, and when intelligible reasons were given we found that mathematical operations beyond a specific use and interpretation kept producing unintelligible relations and results which simply did not cohere for the entire system which used the -numbers and the - operation of subtraction.
This problem was considered so outrageous as to undermine the validity of algebra as a genuine science for nearly 300 years, with the debate centering on what the content meaning of such operations and numbers really represented, if any. Geometry in those days was the queen of the sciences, the surest knowledge humanity had produced and discovered, and most objections to algebra's strange results were based on the fact that geometry did not suffer such silliness as negative quantities. Since the numbers proved to be useful in certain everyday cases as well as simply being an interesting exercise of "what if we just go along, what does it produce?" Most mathematicians, even those against such numbers, nonetheless studied and found eventual applications. That certain numbers, in the way they were contrived to operate, found eventual real use, however, did not ever answer the fundamental question of what these numbers and operations meant in themselves as quantities. This question was still open up to the 1830s, but by that time the use and simple formal acceptance of the negative and imaginary numbers just became so overwhelming that the naysayers were silenced by general indifference and disinterest in the question. The math worked regardless of our ability to comprehend any of it in intelligible ways, and that was that.
With the questions of the intelligibility of mathematics thrown into the dustbin of history, math ceased to be what it was once purported to be, it was no longer the science of quantity and its relations. Formalism eventually won. The numbers no longer represented quantities, the + and - operations no longer represented objects given or taken, square roots no longer necessarily meant intelligible operations, etc. With the fall from grace of Euclidean geometry after more than a millennium of being the queen of the sciences, itself reduced to just another arbitrary formal system with the discovery of new geometries, algebra and its strangeness was saved from one of its strongest bases of attack, those who saw geometry as elegant, simple, clear, and unquestionable.
So what do the negative numbers and the negative operations ultimately mean? Nothing, mathematics simply cared about symbol manipulation and its proper syntax with no meaning necessary other than the operations which moved and related symbols. All of math was shown to ultimately be imaginary.
But if all math is imaginary, the book asks us, if it is all revisable in principle, can we at least make it accord just a bit more with our common sense comprehension so that it remains just that much more intelligible? Why not (- * - = -)? Indeed, why not. In fact, why not a mathematics of quantity, a modern algebra of quantity which shall never produce the strange result of negative numbers which have no physical meaning?
The first half of the book retells the history of this controversy, the second half of the book offers to us a vision of a mathematics that, for those of us who wish to have an intelligible mathematics, can return to these old questions and offer new attempts to approximate if not satisfy the old desire for a fully intelligible science of quantity.