The Polity IV measure used here is certainly also questionable – as would every other alternative – but we chose it as my main source because based on our comparison with alternatives and the paper by Munck and Verkuilen (2002) it is the best available option, particularly if a long-run perspective is the main objective.
We also have to keep in mind that this measure cannot capture everything that matters for a political regime. For example it makes sense to measure corruption or human rights separately from the democracy concept. Not because it doesn’t matter but because all aspects matter and for different question we want to be able to differentiate between the importance of different factors.
Although some writers have questioned or even rejected the peace by trade proposition, their criticisms are not convincing. Beck, Katz, and Tucker (1998) raised the serious technical issue of time dependence in the time-series cross-section data, but Russett and Oneal (2001; see also Oneal 2003 and Oneal and Russett 2003b) responded to the objections raised against their earlier work and demonstrated that those objections do not affect their substantive conclusions. For a while, Hegres (2000) study seemed to necessitate a qualification of the peace by trade proposition. He found that the pacifying effect of trade is stronger among developed countries than among less-developed countries. More recently, however, Mousseau, Hegre, and Oneal corrected this earlier finding and reported: Whereas economically important trade has important pacifying benefits for all dyads, the conflict-reducing effect of democracy is conditional on states economic development (2003, 300). Gelpi and Grieco (2003) suggested another qualification. In their view, trade no longer pacifies relations between autocratic states. According to Mansfield and Pevehouse (2003), another modification of the peace by trade proposition might be required. The institutional setting, such as preferential trade agreements, matters. It is even conceivable that other forms of economic interdependence, such as cross-border investments, exercise some pacifying impact. Foreign direct investment (FDI) certainly promotes prosperity, growth, and democracy (de Soysa and Oneal 1999; de Soysa 2003), but the conceivable pacifying impact of FDI still lacks sufficient empirical investigation.
Neo-realism also puts forth a theory for relative peace to be achieved by suggesting the concept of mutually assured destruction based on the fundamental principles of nuclear deterrence. A concept which helped maintain peace during the cold war between the Soviet Union and the United States of America courtesy of their possession of the nuclear weapon. (Sagan & Waltz, 2010, ) However nuclear deterrence never proposes to establish world peace, nonetheless it does work towards the maintenance of relative peace between two nuclear powers. As states are seen as maximizers of security, nuclear weapons are its last resort to seeking security in a world which offers none on its own. If a state feels sufficiently scared or threatened by the actions of another state in the system of anarchy, then it can pursue nuclear weapons as they are the ultimate deterrent and providers of security. (Sagan & Waltz, 2010, ) The concept of mutually assured destruction functions on the basis of fear of whole scale destruction between two nuclear weapon states. If one state launches its nuclear weapon, it can be assured that the other one will respond in kind via its second strike apparatus and thus ensuring destruction of both the states in question courtesy of the highly destructive powers of the weapon in question. (Sagan &Waltz, 2010, ) Since, the Second World War, no two nuclear states have fought against each other and the example of India and Pakistan is seen as a primary one in this regard outside of the deterrence which existed between and the Soviet Union. Despite fighting three large scale wars against each other since 1947 over the territorial dispute of Kashmir, Pakistan and India have not fought against one another since 1998 when both the countries achieved nuclear strike capabilities, something which goes onto further elaborate on the “peaceful” powers of nuclear weapons and the theory of mutually assured destruction.