Christian Siefkes

Welcome to my home page!

I am a computer scientist, author, and independent scholar. I'm a founding member of Klimaliste Berlin, a new political party that aims to transform Berlin and make it a carbon-neutral and fair city in a carbon-neutral, sustainable, and fair world. Generally I'm in favor of decisive and thorough action in order to shut down the usage of fossil fuels and stop all harmful behaviors that are heating up our planet. Urgent action is now more needed than ever since there is hardly any time left to save civilization as we know it!

Since 2006 I have been working (with some interruptions) as a freelance software engineer and data scientist in Berlin, Germany. My areas of expertise include Python, Ruby and Ruby on Rails, Haskell, Java, data science and data engineering (Pandas, NumPy, Matplotlib, etc.), database integration (SQL, PostgreSQL, Active Record, Redis, etc.), search engine integration (Solr), as well as text classification and machine learning (scikit-learn, OSBF, etc.).

Current clients include T-Systems. Among my former clients are Dropscan, Freie Universität Berlin, Liquid Democracy, Project A, Rocket Internet, and Zalando.

I'm a supporter of the idea of using a regular and simple constructed auxiliary language for global communication instead of relying on national languages such as English, which are hard to learn and inevitably give an advantage to those who have them as mother tongue. I have contributed to Lingua Franca Nova, commonly known as Elefen, and for a while I have developed a language called Lugamun with a vocabulary and grammar based on the most widely spoken languages from around the world. By now I mostly support Esperanto, the most widespread and successful of all constructed auxiliary languages. I'm a regular contributor to the Reta Vortaro (ReVo), the biggest multilingual Esperanto dictionary. I have also created lists of the most frequently used words in Esperanto which you can find in Wiktionary.

I like to write, talk, or research about peer production, free software, open hardware, and commonism. My most well-know works in this area are about commons-based peer production and how to generalize it into the physical world.

I hold a Ph.D. in computer science from the Freie Universität Berlin.

I'm also a historian, researching life in earlier societies, including darker aspects of the history of consumption and trade, such as cannibalism and its connections to slavery and xenophobia. In 2022, Berghahn Books published my book Edible People: The Historical Consumption of Slaves and Foreigners and the Cannibalistic Trade in Human Flesh. In July 2023, I gave a talk on "Slavery, ivory trade and cannibalism in the Congo Basin" at the annual conference of the Social History Society in Colchester, England, based on material from this book. Today, many anthropologists and historians shy away from such topics, maybe because they are considered too "bloody" and associated with colonialist prejudices. But can a history that only looks at "comfortable" topics really be considered complete? I don't think so, and ironically enough, this tendency to look away also means to let colonialists and their forerunners off the hook, since their involvement in such practices is ignored.

My brother Martin also has a website. My uncle Dirk died in March 2016. We will not forget him.


Edible People

Edible PeopleBerghahn Books, New York/Oxford, 2022.

An excursion into one of the darker aspects of the history of trade and commercial exploitation. Human cannibalism has attracted considerable notice and controversy, and yet, certain aspects of the practice have received scant attention. These include the connection between cannibalism and slavery: the fact that in some societies slaves and persons captured in slave raids could be, and were, killed and eaten. Likewise ignored is the connection to xenophobia: the capture and consumption of unwanted strangers. In this book I explore these largely forgotten practices and ignored connections while making explicit the links between cannibal acts, imperialist influences and the role of capitalist trading practices. These are highly important for the history of the slave trade and for understanding the colonialist history of Africa and other regions.

Beitragen statt tauschen

Beitragen statt tauschenAG SPAK Bücher, Neu-Ulm, 2008.

Die deutsche Übersetzung meines Buchs From Exchange to Contributions: das Buch beschäftigt sich dem Potenzial der Peer-Produktion – der Art und Weise wie Freie Software und Freie Inhalte produziert werden. Wir wissen, dass diese neue Produktionsweise von großer Bedeutung ist, wenn es um Software und Inhalte geht – Erfolgsgeschichten wie die von GNU/Linux, Apache oder der Wikipedia sprechen hier eine deutliche Sprache. Aber mein Buch zeigt, dass das noch längst nicht alles ist: Peer-Produktion hat das Potenzial für mehr, bis hin zu einer Umwälzung der gesamten gesellschaftlichen Produktion.

From Exchange to Contributions

From Exchange to ContributionsEdition C. Siefkes, Berlin, 2007.

Peer production – the way in which free software projects such as GNU/Linux and free content projects such as the Wikipedia are produced – has revolutionized the areas of software and content production during the last decades. But does peer production only work for information goods, or can it have a similar effect on the production of physical goods?
I have written a book discussing this question, and showing how peer production can indeed grow beyond the sphere of information. A society based entirely on peer production is possible, and this book describes how.

An Incrementally Trainable Statistical Approach to Information Extraction

Incrementally Trainable Statistical Approach to Information ExtractionVDM Verlag, Saarbrücken, 2008.

My Ph.D. thesis, finished in 2007: The purpose of Information Extraction (IE) is to find desired pieces of information in unstructured or weakly structured texts and store them in a form that is suitable for automatic querying and processing. This book presents a innovative approach to statistical information extraction. It introduces a new algorithm which supports functionality not available in previous IE systems, such as interactive incremental training to reduce the human training effort. The system also utilizes new sources of information, employing rich tree-based context representations to combine document structure (HTML or XML markup) with linguistic and semantic information. The resulting IE system is designed as a generic framework for statistical information extraction.

What You'll Find on My Site

Lugamun (external)

From 2021 to 2023 I was the head of a small group of volunteers developing Lugamun – short for "luga komun", or common language – an easy-to-learn, logical and well-balanced auxiliary language for global usage. Its goal was to allow people who otherwise don't share a common language to communicate effectively and on an equal footing. Lugamun's vocabulary and grammar are based on the most widely spoken languages from around the world. It was developed in a systematic fashion based on an algorithmic process in order to ensure a globally fair and accessible vocabulary. Though I still like Lugamun's philosophy and approach, I have ceased working on it, instead now recommending to focus on better developed and more widespread auxiliary languages such as Esperanto instead.

Lytspel (external)

A simple phonetic respelling for the English language, based on the idea that spelling should be fun, not a burden. The traditional English spelling system is afflicted with exceptions and conflicting rules, making writing and reading texts unnecessarily hard. Lytspel reforms the English spelling to make it strictly follow the alphabetic principle.

Free Software

I have contributed to various free software projects, and have also written a few (mostly small) programs of my own. On this page you can also find a list of my translations for the GNU Project and an overview of my experiences in commercial software development.

Free Society

I'm involved in a blog and wiki discussing whether and how the practices of free software and open content development can be extended to other areas of production, and whether an economy based on this mode of production is possible. My research on these questions has lead to a book which is available in English and German. Additionally, this page lists older texts which I wrote as a student, and more.

Spam Filtering

Spam is ubiquitous, highly adapting to any counter-measures, and most annoying. This makes spam filtering one of the most important and interesting research topics in the field of text classification and text mining. Here you'll find my contributions to this effort.

Information Extraction

This page is dedicated to my Ph.D. project. The primary goal of my Ph.D. research was to develop and evaluate a statistical system for the extraction of information from natural language texts that supports incremental training and that takes the structure of texts into account. My Ph.D. thesis, publications, and software are all available here.

History of Computing

As a student I worked for an experimental teaching project with the purpose of giving computer science students a better insight into how to write good papers and to conduct larger research activities. As the topic area of the project we had chosen historical developments in the fields of computer science and software development; both to open up an interesting field of exploration that is largely outside the scope of usual CS teachings and to provide the students with a better understanding of the history of their own field.


How to get in touch with me.

Keimform Articles

I'm a co-author in the German-language Keimform-Blog, a group weblog discussing whether and in which ways commons-based peer production has a potential that extends beyond the areas of free software and open content production where it has first emerged. Here you can preview my most recent contributions and the latest articles published in the blog by any author.

My Most Recent Articles

Lützerath verteidigen

Christian Siefkes, 07 Jan 2023

© Marius Michusch. Das Bild darf für nichtkommerzielle Zwecke verwendet werden, solange der Urheber genannt und verlinkt wird. Wie ihr ja wahrscheinlich schon mitbekommen habt, steht in den nächsten Tagen die Räumung des Dorfs Lützerath an, das dem Braunkohle-Bergbau, der wohl dreckigsten aller fossilen Technologien, zum Opfer fallen soll. Um das zu verhindern oder zumindest […]

Warum versagt der „ideelle Gesamtkapitalist“?

Christian Siefkes, 26 Jul 2021

Wenn die Firmen im Kapitalismus nicht das Richtige und Notwendige tun, warum sorgen dann nicht die Staaten dafür, dass das passiert? Weil den Politiker:innen die Zukunft zwar egal nicht ist, es aber immer wichtiger ist, dass die Wirtschaft kurzfristig „brummt“ – mit fatalen Folgen.

Wie die drohende Heißzeit mit den Kapitalmärkten zusammenhängt

Christian Siefkes, 23 Jul 2021

Drei Punkte sind entscheidend für das klägliche Versagen des Kapitalismus im Angesicht der Klimakatastrophe: die Borniertheit der Profitmacherei, negative Externalitäten auf Märkten und die Zeitpräferenzen von Menschen und Institutionen.

Es gibt kein 2-Grad-Ziel

Christian Siefkes, 30 Jun 2021

Die Existenz von Verstärkungseffekten, die zum Teil schon heute greifen heißt, dass es faktisch kein „2-Grad-Ziel“ gibt, das die Berechnung einer „sicheren Menge“ an Treibhausgasen ermöglicht, die die Menschheit noch freisetzen kann, ohne sich selbst den Boden unter den Füßen wegzuziehen. Denn das Risiko, dass aus den zwei Grad Erhitzung aus direkt menschengemachte Emissionen innerhalb von Jahrzehnten oder Jahrhunderten katastrophale drei oder vier Grad werden, ist einfach zu hoch.

Heißzeit oder System Change

Christian Siefkes, 28 Jun 2021

Die kapitalistische Entwicklung droht schnurstracks in die globale Katastrophe einer Heißzeit zu führen – eine Katastrophe von einem Ausmaß, wie sie die Menschheit noch nie gesehen hat. Es bleibt sehr wenig Zeit, die Katastrophe noch abzuwenden, und innerhalb des Kapitalismus ist dies so gut wie unmöglich.

Hannah Arendt, das Recht auf Rechte und die freie Migration

Christian Siefkes, 19 Apr 2021

Warum aus Hannah Arendts „Recht, Rechte zu haben“ die Notwendigkeit freier Migration (globaler Freizügigkeit) folgt.

Newest Blog Articles

Verteilte commonistische Planung

Stefan Meretz, 27 Nov 2023

Aus: Thomas Stölner, Uwe H. Bittlingmayer, Gözde Okcu (2023, Hg.): Anarchistische Gesellschaftsentwürfe. Zwischen partizipatorischer Wirtschaft, herrschaftsfreier Vergesellschaftung und kollektiver Entscheidungsfindung. Münster: Unrast. Von Stefan Meretz, Simon Sutterlütti Einleitung Aus dem 20. Jahrhundert könnte man lernen, dass die »sozialistische Übergangsgesellschaft« mehr als nur einige »Muttermale« (Karl Marx) des Kapitalismus trägt, sondern mit diesem eine gemeinsame Basis […]

Antiauthoritarian Communism and Postmonetary Alternatives

Stefan Meretz, 06 Nov 2023

Online-Workshop, 11th of November On saturday, 11.11.2023, AKUT invites you to an Online Workshop on Antiauthoritarian Communism and Postmonetary Alternatives with Anitra Nelson, Friederike Habermann, John Holloway and others. Feel free to distribute the invitation.  Homepage: Time: 11.11.2023, 08:30am – 05:00pm EST / 2:30pm CET – 11:00pm CET Participation link:; Meeting-ID: 919 532 1982 In the 20th century, many […]

Democratic Economic Planning

Stefan Meretz, 17 Oct 2023

Virtual seminar series hosted by the Research Center on Social Innovation and Transformation, Ottawa, Canada. Registration: stremblay (at)

Anarchistische Gesellschaftsentwürfe

Stefan Meretz, 11 Oct 2023

Ein spannendes Buch ist erschienen, und wir – Simon und ich – freuen uns außerordentlich, dort mit dem Beitrag „Verteilte commonistische Planung“ vertreten zu sein. Simon hat in seinem zweiten Beitrag „Parecon: Noch immer Lohnarbeit, noch immer Kapitalismus“ zusätzlich das Parecon-Modell kritisch unter die Lupe genommen (mit Antwort von Robert Hahnel). Ich kenne anderen Beiträge […]

Principles AKUT/Grundsätze AKUT

Simon Sutterlütti, 30 Sep 2023

[Deutsch weiter unten] AKUT was founded. These are its principles: The Association Critique Utopia Transformation (AKUT) develops possibilities for a society free of domination and deals with the ways to get there. At the moment we are working in three fields: joint theoretical work on utopia and transformation, educational work (brochures, videos, conferences, workshops) and […]

Erstes Freiraumfest Graz: 15.-21. Oktober ’23

Marcus Meindel, 19 Sep 2023

Eine ganz herzliche Einladung an euch alle, am allerersten Grazer Freiraumfest teilzunehmen. »Nicht-kommerziell & selbstorganisiert: Das Festival von unten«: Das Freiraumfest mag nicht als Commons-Festival gelabelt sein, aber wäre es das, würde es sich nicht verkehrt anfühlen. Freiraumfest bedeutet hier, dass es eine Woche lang verdichtetes Programm in den selbstorganisierten Spaces gibt und dann noch […]

[Last generated: 2023-12-07] Valid XHTML 1.0 Transitional