If you think this sentiment is dangerous, because you have read that if this left wing party formed a government after the forthcoming Greek elections the Eurozone would be plunged into crisis, I suspect you should reconsider where you get your information from. Here is why.
Syriza wants to reduce the burden of Greek government debt by various means, which would clearly benefit Greece and mean losses for its creditors. Its bargaining position is strong because the government is running a primary surplus. This means that if all debt was written off and the Greek government was unable to borrowing anything more, it would be immediately better off because taxes exceed government spending. In contrast the creditors’ position in such a situation is normally very weak, which is why some kind of deal is usually done to reduce the debt burden. Creditors take a hit, but not as bad a hit as they would if all debt was written off.
It might appear as if the creditors have an extra card in this particular case - they can throw Greece out of the Eurozone. Be absolutely clear, that is a threat being made by the creditors. Greece under Syriza has no intention of leaving the Euro, even if they defaulted on all their debt, so they would have to be forced out. I have never seen it set out clearly how the rest of the Eurozone would force Greece to leave without compromising the independence of the ECB, but let’s assume that they have the power to do so. Would the Eurozone ever carry out this threat?
Expelling Greece from the Eurozone because they wanted to renegotiate their debts would be an incredibly stupid thing to do. For a start, the creditors would lose everything, because obviously Greece would go for complete default in those circumstances. In addition, individuals and markets would immediately worry that the same fate might befall other periphery countries. (The story that Dani Rodrik tells is all too plausible.) What would be the gain?
The standard answer is that by exercising this threat you prevent other periphery countries trying to follow Greece’s example. Moral hazard - the sins that have been committed in your name! In reality the interest rate on part of Greek debt has already been reduced in earlier negotiations (see also Andrew Watt here). There is nothing compelling the core countries to treat each periphery country equally - as Ireland has found out to its cost. Peter Spiegel puts it clearly in the FT:
“How radical is Mr Tsipras’ idea of a Paris Club-style debt restructuring? So radical that, according to three officials involved in the discussions, eurozone officials actively considered such a plan in late 2012. The French-led initiative would have led to Greece’s debt obligations being cut in tranches — much the same way bailout aid is granted — after meeting a series of economic reform commitments.”
So even if some in Germany were stupid and cruel enough to suggest throwing Greece out, it seems inconceivable that the rest of the Eurozone (or the IMF) would allow it. In reality reducing the debt burden in Greece (and probably elsewhere ) would do the Eurozone a lot of collective good. Greece would be able to relax the crippling austerity that has had disastrous economic and social consequences. The core countries and the IMF could at least partially undo the mistakes they made from 2010 to 2012 in first delaying default, and then failing to impose a complete default, mistakes IMF staff  at least now recognise. German taxpayers might be encouraged to understand that the problem since 2010 has not been Greek intransigence but the actions of their own governments in trying to protect their own banks and in dispensing unrealistic degrees of austerity. Philippe Legrain argues the case in detail here. As Thomas Piketty succinctly puts it, Syriza “want to build a democratic Europe, which is what we all need”.
Following a post like this I invariably get comments that tell me about all the terrible things that still go on in Greece. I want to make two final points here. First, if things have not changed following years of acute austerity in Greece, might this mean that we need something else besides more acute austerity? Might it mean we need a move away from the traditional governing elites?  Second, a widely recognised measure of fiscal stance is the underlying (cyclically corrected) primary balance (the deficit less debt interest). Here is the OECD’s latest estimate for 2014. Do not complain that Greece is backsliding on austerity! And before you tell me that the law must be followed, read a post I am proud I wrote.
|Underlying government primary balances 2014, OECD estimates
 The preliminary decision of the ECJ today might have been much more dangerous. For an excellent discussion prior to the judgement see Ashoka Mody.
 Barry Eichengreen and Ugo Panizza doubt whether the primary surpluses that some countries would need to run without more debt relief are politically feasible. I’m a little more optimistic, but that is different from saying that some debt renegotiation would not be beneficial in the longer term.
 There would be the added bonus of seeing a well known economic blogger become a politician!
 My initial version just said IMF, but as Peter Doyle reminds me, this staff critique was not endorsed by IMF management.