In science all generalisations, conclusions, theories and laws are subject to constant verification by new observation and experimentation. If a single instance or proof is found which does not support or substantiate a generalisation or theory it is either rejected or modified accordingly. But verifiability of generalisations, theories, and laws in Political Science is not always possible. Observation cannot provide reliable facts or data and experiment is impossible.
We may, therefore, say that there exists no systematic body of knowledge in Political Science, that can, to use Maclver’s phrase, “serve as a definite guide to the statesman, a science of how to govern, an applied science that does or can do in its field what, say, medicine or engineering does in its field.” “Political Science”, said Harold Laski, “has not the axiomatic quality of mathematics. In its equations the variables are human beings, whose uniqueness prevents their reduction to law in the scientific sense of that much-abused word.”
Another obstacle to the development of a science of politics is the change in the political environment Human life, including political life, is in a State of endless change. All aspects of both human and nonhuman environment are always changing; and beliefs which are true in one environmental situation may become obsolete in another: what is true today may not remain so tomorrow: what is right in one country becomes wrong in another: what is regarded as immoral in one country is regarded as moral in another.
Technological, economic, social and other changes occur which render old traditions and beliefs untenable in new situations. This is the reason why the findings of political scientists ‘cannot be applied when conditions change on which they were based. This fact makes the cumulative and continuous development of Political Science difficult. Moreover, there are several other sciences which also suffer from the lack of exactitude of the natural sciences as is with the political science, such as meteorology, archaeology, and others.