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Learning, thinking,
and creating.

Those three words cover just about all of my interests. I'm curious by nature and I get a lot of satisfaction out of learning about all sorts of subjects. It also matters to me to think critically, and to form as rational and nuanced a picture of the world as I can. But what I enjoy most is making something out of it, whether that's writing an article or building a website like this one.

Lennart van Tuijl

About

Hi, I'm Lennart. Welcome to my corner of the internet.

Right now

  • Started writing on Substack
  • Building LifeCore, a productivity app

I've been curious and eager to learn for as long as I can remember. My interest in science started with the natural sciences, and later I got into the humanities and social sciences as well. When it comes to technology, I'm mostly interested in frontier technologies that contribute to human health and the environment.

I'm also interested in the question underneath all that learning: how do we work out what's actually true? People share the same world and still end up believing completely different things. On my Substack I write about the starkest examples of that, usually in religion, pseudoscience, politics and conspiracy theories. I'm not exempt from any of this myself. We all get things wrong without noticing, and putting my arguments in public is how I find out when I have.

What I enjoy most, though, is doing something with what I've learned, like writing an article on Substack or building a website or app.

Floor-to-ceiling shelves of old leather-bound books with a wooden ladder leaning against them
01

Learning

ScienceBiologyTechnologyEducation
An open hand reaching up towards a lit light bulb floating against a pale sky
02

Thinking

Critical thinkingPhilosophyRationalityPsychology
A desk at night with code open on a monitor and documentation on a laptop screen
03

Creating

BuildingEntrepreneurshipProductsDesign

Writing

Thinking out loud.

Rational Notes is about irrationality in the broadest sense. I'm interested in the human mind, in evolutionary psychology, and in why people end up believing things that don't hold up. That interest naturally leads me to write about specific beliefs, from religion and pseudoscience to conspiracy theories, and about what exactly goes wrong in the reasoning behind them.

Projects

What I've created.

These are the projects I've finished or am working on.

LifeCore

A productivity app I'm building

building

A life OS that brings every component of productivity together in one coherent interface. I'm building it out of necessity: most apps solve only part of the problem, and the ones that do try never quite work the way I want them to.

ProductivityGoalsLife OS
In progressNot public yet

Contact

Say hello,
I'm easy to reach.

If you have anything to ask or share, don't hesitate to send me a message. You can email me, or reach me through one of my socials. I try to reply as quickly as I can.