The digital signals 0 and 1 are the approximations of analog voltages. For example, if the output voltage is more than 0.2volts then it is considered as 1. If it is less than -0.2 then it is considered as 0. If it is in between -0.2 and 0.2, then it is considered as error or corrupted signal.
Lesson 1: Similarly, we can say, Good and Bad are approximations. There is a gray area in between good and bad. Sometimes, as in digital electronics, negative value could be considered as 1 and so is 'Good', in our life. So, we can say everything in this world are not perfect except one thing. That is , the equality of the definition of 1/0 and Good/Bad is perfect. Isn't it? This is what is called "cancellation of an approximation by another approximation".
Lesson 2: Digital electronics just ignored this approximation and went on thinking about what it can do with the "1" and "0" it approximately manufactured. It achieved mathematical calculations, then human logistics, super computing, media, scientific calculations, automation and control, robotics, medical advancements and so many things to name. So, sometimes we have to forget the imperfection of the things we are living with and we have to go and make the best out of that thing.