George Berkeley
Berkeley argued that forces and gravity, as defined by Newton, constituted "occult qualities" that "expressed nothing distinctly". He held that those who posited "something unknown in a body of which they have no idea and which they call the principle of motion, are in fact simply stating that the principle of motion is unknown." Therefore, those who "affirm that active force, action, and the principle of motion are really in bodies are adopting an opinion not based on experience." Forces and gravity existed nowhere in the phenomenal world. On the other hand, if they resided in the category of "soul" or "incorporeal thing", they "do not properly belong to physics" as a matter. Berkeley thus concluded that forces lay beyond any kind of empirical observation and could not be a part of proper science. He proposed his theory of signs as a means to explain motion and matter without reference to the "occult qualities" of force and gravity.
Abdus Salam
During his visit at the Institute of Physics of Quaid-i-Azam University in 1979, Salam had explained after receiving his award: "Physicists believed there are four fundamental forces of nature; the gravitational force, the weak and strong nuclear force, and the electromagnetic force". Salam was a firm believer that "scientific thought is the common heritage of mankind", and that developing nations needed to help themselves and invest in their own scientists to boost development and reduce the gap between the Global South and the Global North, thus contributing to a more peaceful world.