The rise of international relations as a discipline and realist approach to IR has been synonymous with each other. With all its shortcomings, realism has been the most dominant theory in IR which has profoundly influenced the other approaches in the discipline. The differences between Classical Realism and Neo-Realism are explained below.

• The first difference pertains to the question – why states want power? According to the classic realists, the answer is human nature. They would argue that great powers are led by individuals who want to accumulate power and have their state dominate its rivals. Neo-realism traces it to the structure of international system. In an anarchical international system, states cannot trust each other’s intentions and it makes sense for them to be powerful enough to protect themselves in case they are attacked. Neo-realism is also called structural realism as it gives central importance to the anarchical structure of international politics.
• Second, for classic realists, power is an end in itself while for the neo-realists, power is a means to an end and the ultimate end for a state is survival.
• Third, neo-realism followed a different methodology as it relied on methods drawn from microeconomics. It, therefore, claims to be more systematic and scientific than classic realism. Neo-realism was influenced by the behaviouralist revolution of the 1960s while classic realism is based on subjective interpretation of international politics.

Realism would not have predicted the fall of Soviet Union and the end of Cold War as it gives more focus to state as a unit and ignores certain actions of citizens that can threaten the survival of a state. One of the main reasons for the fall of USSR was that in many of its republics, citizens revolted against the Soviet leadership and demanded freedom and independence. Realist approach does not address the new threats to a state – climate change and terrorism. Terrorist groups like the Islamic State or Al Qaeda are also called non-state actors and realism does not have much to say about non-state actors. Critical perspective has challenged the inequality and injustice in IR and raised issues that are often ignored by mainstream theories like realism.

Hence, it can be said that both schools of thought have their own unique contribution in the field of International Relations but Waltz’s ideas have proven to be time tested and offer a better understanding of the developments that took place after the end of cold war especially given the failures during the Covid19 pandemic. Despite numerous differences though, both sets of realism continue to emphasise the 3S- Statism, Self-Help and Survival.