Constructivists argue that norms govern the international system, especially concerning the use of nuclear weapons. The most powerful of these norms is the nuclear taboo. The nuclear taboo states that nuclear weapons are so powerful that their power exceeds nations’ ability to fully conceive of their destructive impact. Instead, they think of nuclear weapons in terms of appropriateness and the nuclear taboo states that it is never appropriate to use nuclear weapons as an offensive weapon ("Constructivism"). This norm is incredibly effective; with the sole exception of the United States during World War II, no country has used nuclear weapons in anger. This holds true even when the state has been considered unstable or rogue, like Pakistan (Charnysh). With over 60 years of historical evidence, there is quite good cause to believe that, regardless of its rhetoric, Iran will conform to the nuclear taboo if it develops a nuclear weapon. The consequences of not doing so would be disastrous for the Iranian government and people.
What the nuclear taboo has done is make atomic weaponry purely defensive. Since no nation would use nuclear weapons in anger, so it says, other nations don’t have to fear nuclear first strikes. Instead, nuclear weapons are purely second-strike weapons, only to be used, if at all, as retaliation for a nuclear strike on the home country. Therefore, they are in the unique position of being able to make one state more secure without lessening the security of any other state. Therefore, an Iranian nuclear weapon acts to increase Iranian security without lowering Israeli security. As long as Israel doesn’t plan on attacking Iran with its nuclear weapons, it need not fear an Iranian nuclear strike.
The constructivist understanding is that nuclear weapons fundamentally alter the character of the state that possesses them. They are so destructive that they make states hyperaware of the actions they are taking. This argument is supported by the research of John Gaddis on the effect of nuclear weapons on war. Gaddis asserts that any weapon “which increases…optimism is a cause of war. Anything that dampens that optimism is a cause for peace” (Gaddis). Nuclear weapons, and the massive damage they can inflict, have permanently created a pessimistic view of war between nuclear states. This pessimism has the effect of tampering ideological differences between states. Although hateful rhetoric may exist between states, the realities of nuclear war force those states to engage each other in a more measured manner.
Some would argue, however, history does not bear this out. They would point to the issues surrounding unstable and transitioning states: that these states tend to behave more aggressively than would normally be expected (Mansfield). It can be argued that the Iranian government is inherently unstable, and thus cannot be trusted to act reasonably. While some would argue that this invalidates the operation of constructivist norms, history backs up the nuclear taboo even in unstable nations. For example, Pakistan began developing nuclear weapons during a period of great unrest in the 1970s (Charnysh). The severe security environment in which it exists has provided numerous opportunities for the use of nuclear weapons since the programs completion in 1990. That Pakistan, even in its unstable condition, has not used its weapons strongly suggests that nuclear weapons are so destructive as to be above the realm of consideration even within unstable states.
If Iran were to develop nuclear weapons, the dynamic between it and Israel would become very similar to that between the U.S. and the U.S.S.R. during the Cold War. Both nations stood ideologically opposed to each other, and continually spouted incredibly hateful rhetoric, but both sides recognized that any action on their part could spiral out of control rapidly. And with nuclear weapons, that spiral led directly to the near-immediate destruction of both of their states. So, while their rhetoric remained vitriolic, their actual interactions were as restrained as possible (Gaddis). The same logic would apply to Iran and Israel. Although they could continue to fire words at one another, the ideological demands would have to be tempered by the nuclear reality. Any conflict between the two nations would result in state suicide. And that is something no state wants. This serves to counteract the long-standing animosity between the two nations that constructivism says would lead into conflict. Therefore, the odds of a violent conflict between the two nations would drop dramatically and both would more secure because of it.