Boundaries of Sciences and Metaphysics by the Two Criteria of Verification and Falsifiability

Philosophers of science present different criteria for the distinction between natural sciences and metaphysics. Logical positivists by accepting inductive logic in science as a tool for collecting information, lay emphasis on observation and induction and in this way consider absolute justification of scientific statements possible.
These philosophers by proposing the criterion of verification for the problem of demarcation and meaningfulness, not only consider the speculative systems of metaphysics non – scientific, but count them as absurd. Whereas the first step in scientific method can not be observation and false sensory statements never can be solid foundation for science. Also the principle of induction is unjustifiable on the principles of this school. In addition, the statement “truth and meaning of a sentence depends on its verification” is neither analytical nor its truth has been proved by experience.
For the supporters of falsifiability theory (like Popper) scientific investigation, during the three stages of encounter, is carried out with problem, invention of theory and testing. Any theoretical system is scientific in so far as it can be subjected to criticism and resist against those criticisms. But this criterion is not acceptable either because on the basis of it the existential statements should be counted as non-scientific and metaphysical. In addition, The history of scientific advancements testifies to the fact that the scientists by observing incompatible instances never relinquish of their own theories. After Popper, Lakatosh has suggested that the research programs, provided that they are consistent and having a program which guarantees the continuation of investigation and novel predictions, should be considered scientific, and on the basis of the same criteria they should be called progressive or on the decline.