Fears of a chain-reaction arms race in the Middle East following Iranian proliferation are based on flawed assumptions
These are major accomplishments in preventing proliferation in the Middle East, and they contradict the worst-case scenarios about a nuclear Iran. Yet they have done little to reassure those who expect a chain reaction of proliferating states.
Such mistaken beliefs are due in part to the West's poor understanding of Iran. After more than 30 years of severed diplomatic, cultural, and educational relations with the country, the West knows little about Iran's leadership, national aspirations, and culture. Because of this, policymakers have a difficult time thinking about the implications of a nuclear Iran and resort to simplistic grandstanding, reprising outdated political fears that lack historical nuance or modern perspective. The exaggerated fears have been useful, too: had the United States not presented Iran's nuclear aspirations in the darkest of lights, it may not have been able to gain support for four rounds of UN sanctions against the Islamic Republic in the last few years.
Another reason for the persistence of worst-case thinking is that the domino analogy is often discussed interchangeably with bilateral arms races, such as those between the United States and the former Soviet Union, and between India and Pakistan. These are two distinct concepts, however. The Cold War and South Asian cases represent dyadic arms buildups -- a scenario that cannot be ruled out in the Middle East. Even though this hypothetical should be of great concern, it is far from the nightmare nuclear domino effect, which by definition requires many more countries to speedily develop nuclear weapons. In the Middle East, this type of rapid development is just not technologically feasible.
Fears that Iranian development of a nuclear weapon would spark a nuclear arms race in the Middle East are not supported by the historical record or a careful examination of the motivations and strategic interests of potential proliferants (ex. Saudia Arabia, Turkey).