To answer this question we first need to define and contrast the two different types of state. An authoritarian state is one that enforces a policy of strict obedience, compliance and may use tyrannical and domineering measures to obtain this. A vote system may be in operation but any dissenting section of the population may come under threat from the government in control thus making the vote a mere stage show. Unlike the above a democratic state sees individual freedom as paramount to the success of a capitalist democracy, which has a system of government influenced by the whole population via the use of representatives.
We assume the word peaceful used in this context is the opposite of war but war is the most extreme consequence of the bad reaction between two or more states. Actions of other states may cause another to experience civil unrest, civil panic and changes in legislation; most commonly an occurrence in democratic states as seen in light of 9/11, which I will discuss later on in the essay. 1945 and the end of World War II was a significant turning point with regards to peace between democratic states. Before 1945 'The League of Nations' was an attempt to avoid conflict like the Great War from recurring.
History revealed that this was a failure. Woodrow Wilson initiated the idea of a League but congress eventually rejected the idea of America becoming part of this 'League' saying it was a European problem and attempted to separate the League from the treaties. In 1921 separate treaties were ratified between Germany, Austria and Hungry but due to the missing cornerstone and hence the initiator of the league, it was powerless and impotent; and again the world was on the brink of war only 20 years later.
A fact that needs to be considered is that there hasn't been a major, long running conflict between two democratic states since 1945 but there have been many conflicts between authoritarian states. For example the Iraq-Iran war and the ongoing conflict between Pakistan and India, according to the definition of democracy reveal that democracies are not hostile towards other democratic states. This may be due to the fact that they are scared of each others military power or of upsetting vital trade agreements or its allies.
Roger masters states that: "… the circumstances of human evolution suggest that some kinds of political regimes – notably autocratic and totalitarian ones – are unnatural and unjust. Conversely, regimes featuring constitutional government, liberal freedoms, and democratic participation are naturally unjust. "1 Therefore can we assume that as authoritarian states are unjust they are more inclined to be hostile and that democracies being just are less inclined?
The international political environment may be a great influence on why hostilities occur between authoritarian states rather than democratic. Authoritarian states are generally not as advanced economically or otherwise as their democratic counterparts that may be a contributing factor why they may be more hostile. Also the geographical layout of the states, namely in the Middle East and the grappling for resources, mainly oil may cause tensions leading to war or conflict (Iraq's invasion of Kuwait).
Europe doesn't o have an essential commodity like oil; it relies on its economic strength through tourism, the service sector and strong connections with the only remaining super power, the US. The present day UN can be seen as a more successful version of the League of Nations. It seems that democracies are constantly striving after peace but in turn is this making their states less peaceful? In the year 2000 the UN had 189 members and one of its main objectives stated in the UN charter was to "Maintain international peace and security….promoting and encouraging respect for human rights… ".
By no means is the UN ever seen as the aggressor, rather the international police force that deals with breaches of human rights on a large scale or tries to prevent usually authoritarian states from warring. This coalition of what are now hundreds of democratic countries must reveal that at the core democratic states are more peaceful. Maybe democracies have come to see that negotiation and deliberation over difficult international disputes is a far better and cost effective way of resolving them as opposed to war and oppression.