Category Mistakes

Category mistakes by Dijkstra, Hoare, and others

Lecture 3: "Turing's 1948 Bridge: from Logical to Practical Machinery"


28 January 2021

Many Turing scholars share a dualistic outlook on science and technology, distinguishing between non-causal (abstract) objects and causal objects. This outlook stands in stark contrast with Turing's monistic thinking and his answer to what a Turing machine meant to him in 1948. ......

... forthcoming ... in 2022 ...

[Last update: 22 November 2021]


Chapter 1 of Turing Tales

The first chapter of my 2016 book Turing Tales is made available here. I explain my methodological stance on the history of computer science, and introduce the topic of "conflations," which I believe is key to understanding the history of science and technology.

Hopcroft and Ullman


24 October 2017

Is the history of computer science solely a history of progress? I don't think so. Judge for yourself by reading the present post in which I scrutinize the famous textbooks of John E. Hopcroft and Jeffrey D. Ullman.

Quotes from 1969 and 2007

I start by comparing the following two quotes. The first quote comes from Hopcroft & Ullman, 1969:


`Plato and the Nerd,' Part 2b: Computer Science & Descriptions vs. Software Engineering & Prescriptions


23 September 2017


One of Edward A. Lee's main topics in his book, Plato and the Nerd: The Creative Partnership of Humans and Technology (MIT Press, 2017), is the contradistinction between science and descriptions on the one hand and engineering and prescriptions on the other hand. Reading between the lines, Lee is addressing the big question: Is computer science really a science?



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