A philosophical term often used by Immanuel Kant, among others, roughly translated as 'the thing as such' or 'the thing in itself'. With that, Kant meant an existence that is independent, not connected to the understanding of man. Das Ding an Sich is the world by itself, before it is adjusted to fit the requirements of reason.

According to Kant, the only fact we can know about das Ding an sich is that such things do exist. Since everything we perceive is affected by our ideas about understanding and reason, das Ding an sich is of course entirely beyond our grasp.

Thus, declared Kant, we should not waste our time wondering about what things are really like, since we can never get accurate, untainted information about things as they truly are. Kant was content to concentrate on the appearances of things - otherwise, we could never get any information at all, since everything we think we know about things as such is already tainted by our perception.