by Carl Pierer

In the first part of this essay, the axiom of choice was introduced and a rather counterintuitive consequence was shown: the Banach-Tarski Paradox. To recapitulate: the axiom of choice states that, given any collection of non-empty sets, it is possible to choose exactly one element from each of them. This is uncontroversial in the case where the collection is finite. Simply list all the sets and then pick an element from each. Yet, as soon as we consider infinite collections, matters get more complicated. We cannot explicitly write down which element to pick, so we need to give a principled method of choosing. In some cases, this might be straightforward. For example, take an infinite collection of non-empty subsets of the natural numbers. Any such set will contain a least element. Thus, if we pick the least element from each of these sets, we have given a principled method. However, with an infinite collection of non-empty subsets of the real numbers, this particular method does not work. Moreover, there is no obvious alternative principled method. The axiom of choice then states that nonetheless such a method exists, although we do not know it. The axiom of choice entails the Banach-Tarski Paradox, which states that we can break up a ball into 8 pieces, take 4 of them, rotate them around and put them back together to get back the original ball. We can do the same thing with the remaining 4 pieces and get another ball of exactly the same size. This allows us to duplicate the ball.
The second part of this essay demonstrated a useful consequence (or indeed, an equivalent) of the axiom of choice, known as Zorn’s Lemma and looked at a few applications of this Lemma. Two positions have been mapped out in the course of this essay. On the one hand, the axiom has very counterintuitive consequences, so much so that they’ve received the name of a paradox. On the other hand, the axiom proves to be very useful in deducing mathematical propositions. These considerations lead back to the question that had already been raised at the end of the first part: how are we to decide on the status of an axiom, on whether to accept it or reject it?
In this third and final part of the essay, we will take a more philosophical approach to this problem. In particular, we will look at a possible resolution offered by Penelope Maddy in her Defending the Axioms. The solution offered would lead onto further questions about the nature of mathematics: what is mathematics actually about? At the same time, Maddy’s view is based on a certain conception of proof that does not really reflect mathematical practice. The essay, due to limitations, only hints at a different perspective offered by looking at what mathematicians actually do and what role proofs play for them. Read more »


Although frequently lampooned as over-the-top, there is a history of describing wines as if they expressed personality traits or emotions, despite the fact that wine is not a psychological agent and could not literally have these characteristics—wines are described as aggressive, sensual, fierce, languorous, angry, dignified, brooding, joyful, bombastic, tense or calm, etc. Is there a foundation to these descriptions or are they just arbitrary flights of fancy?
He flew so fast and so close to the sun that it took an entire lifetime to fall back to Earth.
I recently read Simone Weil for the first time after having come across numerous references to her over the past year. I broke down and bought Waiting for God despite the intimidating and frankly confusing title. I was not disappointed. One of her essays in particular, “Reflections on the Right Use of School Studies in View of the Love of God,” has opened and focused my thinking on education and learning in general, whether for children or later in life for the rest of us. 



Opera as resistance? Music as re-enchantment?
When it comes to evil, nobody beats Hitler. He committed the biggest mass murder of innocent humans in all of history.

Many years ago in 1991, in my first job out of college, I worked for a small investment bank. By 1994, I was working in its IT department. One of my tasks was PC support and I had a modem attached to my computer so that I could connect to Compuserve for research on technical issues. Yes, this was the heydey of Compuserve, the year that the first web browser came out and a time when most people had very little idea, if any, what this Internet thing was. 
Novels set in New York and Berlin of the 1980s and 1990s, in other words, just as subculture was at its apogee and the first major gentrification waves in various neighborhoods of the two cities were underway—particularly when they also try to tell the coming-of-age story of a young art student maturing into an artist—these novels run the risk of digressing into art scene cameos and excursions on drug excess. In her novel A Lesser Day (Spuyten Duyvil, second edition 2018), Andrea Scrima purposely avoids effects of this kind. Instead, she concentrates on quietly capturing moments that illuminate her narrator’s ties to the locations she’s lived in and the lives she’s lived there.
Little Miracles 2:
