Syriza has won the Greek election, which is the result I hoped for. For some this heralds the death of neoliberalism. To celebrate, George Monbiot - whose journalism consistently tells me more than most other journalists - says that here in the UK we should no longer vote tactically, but instead vote for what we want. What dangerous nonsense!
At least he is honest in what such an approach implies. Anyone who votes Green in any seat where Labour has a chance to win, aside from maybe a few seats where the Greens have a chance (more realistically one or two), is voting for a Conservative government. They will be in small part responsible for what happens under that government. (Not voting in a seat Labour has a chance to win is almost as bad.) This is going to be a tight election, so it matters. 
Monbiot says “If Labour wins in May, it is likely to destroy itself faster and more surely than if it loses, through the continued implementation of austerity.” His normal high standards of journalism based on solid research go out of the window. I have, along with the IFS and Resolution Foundation and many others, repeatedly pointed out that there is a huge difference between Labour and Conservative fiscal plans beyond 2015. It is quite possible that we will see very little additional fiscal tightening under Labour, and a lot more public investment.
But with Monbiot in this mood, all this means nothing. The additional hardship that those that depend on the state will undoubtedly suffer if Labour do not win: collateral damage for the eventual triumph of the left. The disintegration of the NHS starved of funds: it will happen anyway - but the last Labour government raised taxes to increase NHS spending! This is not a strategy based on any kind of analysis, but wishful thinking because he finds it distasteful to vote tactically. (The British people had a chance to change their electoral system, and they chose not to.)
In looking at Labour, he sees only their departures from his own vision, and ignores their virtues and the realities of gaining power in today’s environment. He thinks Labour is currently silent on the evils of austerity because they believe in its virtues, whereas in reality they have been forced into this position by mediamacro’s obsession with the deficit. That is why they do not publicise their very different fiscal plans, but good journalism should see through that. Wouldn’t it be nice to have a prime minister who was prepared to stand up to the Murdoch press - oh wait. Wouldn’t it be nice to have a prime minister who said: “This country is too unequal. And we need to change it." - oh wait again (see postscript).
To say that Monbiot’s analysis represents a profound misreading of history seems trivially obvious, but not for left utopianism. Monbiot says “Fearful voting shifts the whole polity to the right.” Where is the evidence for that? Neoliberalism did not triumph because the left decided to compromise. Yes Greece voted for Syriza, but only when half of its young people were stuck in unemployment. Is that the future that he hopes for by abandoning tactical voting?
Parts of the radical left has always suffered from this misty eyed idealism, where through blurred vision everyone else looks the same. I remember being told by otherwise very intelligent people on the left that there was no real difference between George Bush and Al Gore. Monbiot described voting No in the Scottish referendum as “an astonishing act of self-harm”: no matter that the SNP tried to deceive the electorate that they would at all times be better off independent; a sorry claim given what has subsequently happened to the oil price. No doubt some said in 2010 that a future Labour government would be much the same as a Conservative government. Please, just look at the evidence.
So, to repeat, anyone voting Green (or failing to vote) in a seat that Labour can win but the Greens cannot will in part be responsible for the consequences of a future Conservative government.
Postscript (19/2/15): Here is a link to those seats where this might apply.
 An interesting question, from an academic point of view, is whether this argument is symmetrical, applying to UKIP and the Conservatives. Perhaps not in one sense. If Labour loses because of votes lost to the Greens, the reaction within the party will simply be to look for a more telegenic leader. If the Conservatives lose because of votes lost to UKIP, perhaps there is a chance that the Conservative Party will merge with UKIP, and adopt leaving the EU as policy.