Predicting the future from the past is not possible, but a careful study of history can be illuminating. This is true of economic sanctions that go back a long way in history. The first known example was in 432 BC, when Athens sought to choke the economy of the city-state of Megara by excluding its merchants from Athenian controlled territories.
Back then - and often today - sanctions contributed to war (in that case, the Peloponnesian War) rather than averting hostility.
The incidence and severity of sanctions have risen sharply in recent times. From 1914 to 1990, unilateral sanctions were introduced 115 times, compared to only two multinational sanctions by the United Nations (against Zimbabwe, then Rhodesia, in 1966 and South Africa in 1977).
Starting in 1990, sanctions were implemented more frequently, totalling 66 by 1999. Helped by the disintegration of the USSR and the changing power balance in the Security Council, multilateral sanctions rose: to date they've been used 20 times, against countries such as Somalia, Sudan and Iran.
Used as punitive measures to force a change in another government's policy behaviour, sanctions are far more commonly used by large nations and entities against smaller ones. The United States accounted for two thirds of all sanctions before 1990. During the Clinton administration alone, 35 sanctions were introduced affecting 2.3 billion people worldwide. Sanctions inflict untold human distress, but they are often justified as a more ethical alternative to war.
The question of what makes a sanction "successful" continues to elude both proponents and critics. According to one comprehensive study, only one third have historically succeeded in achieving their stated objective, although other experts consider the success rate to be much lower, at only 5 per cent.
Among notable "success" stories was the total blockade of the Iranian oil industry in 1953 that helped to bring down Mohammad Mossadegh, the country's elected prime minister. The end of the apartheid regime in South Arica and prospects for opening Myanmar to democracy are more recent examples.
By contrast, there is no shortage of failed sanctions especially in the context of nuclear non-proliferation: of the four countries that developed nuclear weapons capability after 1970 (India, Pakistan, North Korea and Israel), only Israel escaped sanctions.
But establishing what "success" means requires two further questions: ascertaining a sanction's real objectives, and asking at what cost? Objectives can be opaque and very different from those stated. In practice, these vary widely from nuclear non-proliferation (Iraq and Iran) to respect for human rights (Myanmar) to counterterrorism (Hamas and Al Qaeda) and outright regime change (Syria).
Similarly, costs cannot be kept out of the equation when assessing outcomes - ends do not always justify the means. With sanctions, a country can be reduced to ruins but for what ends? And does defeat constitute success?
From 1990 to 2003, the harshest post-war sanctions in history pushed Iraq's economy, according to the United Nations, back to a "pre-industrial age". Falling life expectancy and doubled infant mortality rates, and extensive damage to physical and social infrastructure, were easy to document. Harder to quantify were hidden costs such as heightened sectarianism as sanctions gave the Baathist regime a justification for annihilating civil society institutions.
So what about the current economic sanctions on Iran? Isn't the recent currency upheaval another indication of an economy in distress and hence of imminent "success" for sanctions?
On several counts, Iran sanctions might present a textbook case for success among proponents, keeping in mind the point about their objectives and possible costs.
First, Iran is highly dependent on the rest of the world to buy its oil and other exports and to sell it food and industrial goods.
Second, sanctions against Iran have become ever more comprehensive in both the sectors affected and the number of countries that have signed up. Third, although it's the third-largest country in the Middle East and North Africa by GDP, and the 32nd in the world, Iran is dwarfed by the sanctioning bloc. The US and EU combined account for 40 per cent of world GDP, 80 times Iran's 0.5 per cent.
A fourth and final factor - the state of the domestic economy and political landscape - presents a more nuanced picture. Here, history is more relevant. Despite Iran's poorly managed economy and well-known structural weaknesses, its political scene is not conducive to a rapid resolution of the nuclear stand-off.
First, ideologue regimes set a high pain threshold for their populations. Second, Iran's complex labyrinth of decision-making and intense factional politics thwart easy prospects for an internal solution. Third, as we have seen elsewhere, sanctions can play into the hands of the most extreme elements within a regime, entrenching attitudes and stifling scope for democratic change of behaviour.
The Middle East analyst Gary Sick once observed of Iraq's former regime: "Sanctions do not persuade dictatorial regimes to abandon projects that they think are central to their security and survival or even their self-image." This lesson was learnt the hard way in Iraq.
Will Iran and the "international community" pull back from the precipice and allow imaginative international diplomacy to take its course?
Judged by history, the answer may not be encouraging.
Hassan Hakimian is the director of the London Middle East Institute at SOAS, University of London