In 1920, a group of philosophers, scientists and economists gathered in Vienna city of Austria. This new school of thought was famous by the name of Vienna Circle. The philosophy which they developed was known as logical positivism. Young AJ Ayer was the man who introduced this school of thought in England. The rise and fall of logical positivism is the most spectacular story of 20th century philosophy. Logical positivism was broadly successful, and some of its key ideas became widely accepted as common-sense truth among the general public. For instance, people routinely make a sharp distinction between facts and opinions, thinking that this is trite and obvious. They do not realise that they are stating the conclusion of a complex philosophical argument which is fundamentally unsound. When scientists talk about electrons, they are just using a shorthand language to describe some rather complex collection of observations that they have made in their laboratories They were totally against the old concept of Philosophy called metaphysics and rejected the whole philosophy of Metaphysics. However, renowned Philosopher Immanuel Kant in the eighteenth century said that we cannot get the knowledge of things which are beyond our empirical experience. But they went a step further from Kant and said that “any statement that was not either a formal statement (a statement in logic and mathematics) or empirically testable has no meaning.” The most important work of this school was their famous principle called Principle of Verifiability. According to this principle, the meaning of a proposition is the method of its verification. What they actually want to prove from this principle and what was their main purpose? According to them, sense perception is the only source of true knowledge and all other sources of knowledge are false and meaningless. They meant that all the knowledge which we cannot get through our senses is false. The main focus of the logical positivism was on sense perception and experience that was the reason that they have rejected metaphysical knowledge. This school of thought considered science as the only valid source of knowledge, while metaphysics and religions were invalid in their view. Philosophers called it the ‘demarcation problem’: how do we draw the boundary line between science and religion? An obvious answer would be that religion requires faith in the unseen — heavens, angels, afterlife, God, while science deals with the real world around us. However, this runs into the problem that science also requires faith in positrons, quasars, gravity, electromagnetic fields, and many other un-observables. The positivists found a solution: we can translate references into unobservables by their observable implications. For example, gravity is not observable, but it implies that planets will have elliptical orbits. According to positivists, when we use the word ‘gravity’, what we really mean is that the planets have elliptical orbits (and all other observable implications of gravity). With this clever philosophical manoeuvre, the positivists showed that despite appearances to the contrary, science does not require faith in the unseen. When scientists talk about electrons, they are just using a shorthand language to describe some rather complex collection of observations that they have made in their laboratories. This school of thought was worldwide accepted till 1950, however after that by the emerging of Two Dogmas theory and other school of thought which says that Principle of Verifiability was not itself verifiable while some of the key members of the school like Carnap, seems to have anticipate these problem to some extent. The writer is a member of Pildat Youth Parliament, Pakistan. He can be reached at rafimahsud704@yahoo.com and on Twitter at Rafi.mahsud@twitter Published in Daily Times, October 20th 2017.