85 years after its formal establishment, the discipline of International Relations is currently engaged in what is known as the ‘Third Debate’. At the heart of this debate is the question “to what extend can society be studied in the same way as nature?”
Positivists hold that the social world is not fundamentally different form the natural world and that, as a result, the same epistemology applies. Positivists aim to explain the social world and believe that causal laws and generalisations can be found through observation. Post-positivists argue that the social and the natural world are not alike and that scientific explanation is neither a valid nor an adequate form of inquiry for the social sciences. According to this view, the social world primarily consists of ideas and concepts that cannot be translated into scientific terms but need to be interpreted. Hence, the aim of post-positivists is understanding social phenomena.
The two positions are commonly perceived as mutually exclusive and the advocates of the two camps are hardly willing to engage in a constructive debate. “This Third Debate will not be much of a ‘debate’ if its protagonists are not speaking to each other, but that is where things largely stand.” Nevertheless, Wendt, among others, has argued that social science in general and International Relations in particular might benefit less from siding with either positivism or post-positivism, but more from combining the two, and that it is indeed possible to build a bridge between the two philosophies of science. Such a combination would acknowledge the ontology of social science to be post-positivist, that is idea-based, while at the same time proposing to adopt a positivist epistemology, although pure scientific explanation and empiricism are not seen as appropriate methods.
Before looking at the combination of the two philosophies of science and its application to social sciences as well as its possible benefits, it seems appropriate to discuss positivism and post-positivism in more detail in order to understand what Wendt proposes to combine. Secondly, this essay will argue that due to the distinct subject matter of social science, the application of positivism alone appears to be inadequate. Yet, so does post-positivism, because it denies that any form of scientific inquiry is possible beyond subjective interpretations of social processes. “The social sciences are denied, in principle, decisive test situations for their theories.” Hence finally, this essay will conclude that Wendt’s ‘via media’ between the two positions appears to be an appropriate and possible approach if, indeed, social science is to become ‘scientific’.
One of the tenets of positivism is methodological monism, or the idea of the unity of scientific method amidst the diversity of subject matter of scientific investigation.
As a result, advocates of positivism hold that social action can be studied in the same way as nature, that is, by testing assumptions and generalisations, found by employing logic and reason, against empirical observations of reality. “Observation is an intelligent activity of bringing concepts to bear.”
For positivists the power of theory lies in its ability to explain and predict. Therefore, positivists commit themselves to the Humean conception of cause as well as they accept the deductive-nomological model (DN model) developed by Popper and Hempel. Whereas the value of causal laws is their ability to establish constant links between events, with the DN model one can logically deduce an explanation for a statement or event (explanandum) from the interplay of applicable laws and the initial conditions (together they are known as the explanans). Because the explanandum is logically deduced from the explanans, the explanation is also a prediction for future situations of the same kind.
In International Relations, Realism is perhaps the strongest supporter of the positivist philosophy of science. “Realism is essentially a call for the application of scientific method.” Initially, the discipline was dominated by Idealism, which, unlike the natural sciences, employed normative methods. Realists rejected the Idealist view that the subject matter of International Relations was too different from that of the natural sciences to employ the same methods, hoping to find causes and laws of human behaviour by applying scientific methods.
 With the establishment of the Chair of International Relations at the University of Wales in 1919, International Relations were for the first time recognized as a separate discipline.
 Roy Bhaskar, The Possibility of Naturalism: A Philosophical Critique of the Contemporary Human Sciences (2nd edition), Harvester Press, Hemel Hempstead, 1989, p.1
 Alexander Wendt, Social Theory of International Politics, Cambridge University Press, Cambridge, 1999, p.90
 Wendt argues that, although post-positivists want to make us believe the opposite, it is possible to acquire knowledge about society and that “nothing in the nature of social kinds means they are uncaused.” (Wendt 1999, op.cit., p.77)
 Bhaskar, op.cit., p.45
 Georg Henrik von Wright, Explanation and Understanding, Cornell University Press, Ithaca NY, 1971, p.4
 Martin Hollis and Steve Smith, Explaining and Understanding International Relations, Clarendon Press, Oxford, 1992, p.52
 ibid., p.45
 ibid., p.45