Kant touch this

It is a pun – Kant sounds like can’t – printed under a portrait of Immanuel Kant in red sunglasses. The philosophical bonus is that it is literally true of his theory. For Kant we only ever know things as they appear to us through space, time and the categories of the understanding; things as they are in themselves remain beyond our reach. So, strictly speaking, you cannot touch this.

In German it is said with a short open a, roughly like “kahnt”. English dictionaries accept both “kahnt” and a version rhyming with “pant”. In British English, where “can’t” is also pronounced with a long ah, philosopher and contraction sound almost identical – which is why generations of students have made the same joke.

The thing in itself (Ding an sich) is an object as it exists independently of how it appears to us. In the Critique of Pure Reason (1781, revised 1787) Kant argues that all our knowledge is of appearances, shaped by the forms of intuition, space and time, and by the concepts of the understanding. We can think the thing in itself, but we cannot know it. Kant also calls it the noumenon, as opposed to the phenomenon.

It is Kant’s supreme principle of morality, set out in the Groundwork of the Metaphysics of Morals (1785). Its best-known form says to act only on a maxim that you could at the same time will to become a universal law. Another says to treat humanity, in yourself and in others, always as an end and never merely as a means. Unlike a hypothetical imperative, it holds regardless of what you happen to want.

Sapere aude is Latin for “dare to be wise” or “dare to know”. The phrase comes from Horace’s Epistles (I.2.40). Kant made it the motto of the Enlightenment in his 1784 essay What Is Enlightenment?, which defines enlightenment as humanity’s emergence from its self-incurred immaturity and translates the motto as having the courage to use your own understanding.

David Hume. In the Prolegomena to Any Future Metaphysics (1783) Kant admits that the memory of Hume was what first interrupted his dogmatic slumber. Hume had argued that our idea of cause and effect rests only on habit, not on reason. Kant took this challenge seriously and answered it by showing that concepts such as causality are conditions of any possible experience.

Hardly. Apart from some years as a private tutor in country households nearby, roughly 1748 to 1754, Kant spent his whole life in Königsberg (today Kaliningrad) and apparently never left East Prussia. Legend has it that neighbours set their watches by his daily walk. Yet he lectured on geography and wrote on cosmopolitan law and perpetual peace.

Start short with What Is Enlightenment? (1784) and the Groundwork of the Metaphysics of Morals (1785), his most accessible major text. Then try the Prolegomena (1783), which Kant wrote as a shorter route into his theory of knowledge, before taking on the Critique of Pure Reason itself. A good secondary introduction helps with the terminology.

For philosophy students in their first Kant seminar, teachers who have heard the pun a hundred times and still smile, and anyone who loves a good groan-inducing wordplay. It comes as a classic T-shirt, women’s T-shirt, sweatshirt, premium hoodie, mug and sticker.