Dishonesty makes me crazy.

Lazyness makes me upset.

Draw back: To avoid an issue or commitment. I can't understand the meaning of the post. English natives, please clarify.

I would suggest gravity pushing everything around to a common center, but gravity can't be seen either. 

I would like to set another question. As on a magnet, opposite poles attract. Then, if the north of the earth keeps the north pole of a big magnet, then the tip of a compass pointing to north pole is the south pole of the magnet, right? Or the opposite?

But magnetic field can be seen either...

Do you see the air? Then stop breathing and you will recognise its existence without seeing it, quickly. But as a matter of fact, using sensors, and sensing earthquakes, it is possible to be sure that earth has a core as what this core is made  of. 

I see only advantages on having English as a global lingua franca. Technically speaking, I think everybody should speak only one language, and this language should be English. I speak Portuguese natively and, by comparison,  English is much easier to speak than Portuguese. Some examples. Portuguese words have gender. A casa, o carro. Portuguese verbs depends on the persons. Eu aprendo, tu aprendes, ele aprende, nós aprendemos, vós aprendeis, eles aprendem. With not speaking about future: Eu aprenderei, tu aprenderás..., past: eu aprendi, tu aprendeste...and so on. Adjectives have plural and gender. Alto, altos, alta, altas. Portuguese letters have accent markers. Á é õ.

How could the good (I mean, the khowledge) be spead without the use of a common language? The answer is yes.