If you believe in getting a decent outcome, then you should adjust your methods of achieving it to those that are most likely to find success.
And it's on that basis that the various campaigns to boycott all things Israeli – from products, to businesses, to culture – have been a stupendous failure.
There's even a strong argument that the notion of boycotting Israel has become such a cause celebre that for many narcissistic supporters (though not all) it's little more than a self-congratulatory throat clearance, another lapel badge to show off your right-on credentials.
A handful of companies have stopped buying certain products from Israel, a few investors have withdrawn finance for Israeli projects, some universities don't collaborate with the country's universities, a number of bands won't play concerts there, etc etc.
But the de facto occupation of Gaza continues. It's still blockaded, Gazans have little freedom to move, they are still bombarded by the whistles and growls of Israel's hi-tech military machine. Life in Gaza is, as many have said, like living in an open-air prison. The boycott is at best largely ineffective, at worst a distracting waste of time.
And there are several problems with it.
Why just Israel, which appears to be the sole target of many campaigners? Yes the movement has a clear goal of ending the Palestinian struggle, but the calls to boycott Israel are unique.
No other state seems to have its own version. There is an obvious inconsistency here. Where's the boycott Russia campaign? Where's the boycott Saudi Arabia campaign?
Take U2, a band supporting the Israel boycott, as an example. U2 coins it in large tours across America, playing to hundreds of thousands of fans.
Yet the US is a country that uses drones in unilateral attacks that kill civilians as well as combatants and detains and tortures people without trial in Guantanamo Bay, among other clear breaches of international law.
Following the logic behind the boycott of Israel, U2 shouldn't set foot on American soil, let alone twang a guitar string even once while they're there.
If the premise for a wholesale boycott of a state is that it is in breach of international law, then you could make a case for boycotting almost every single country on the planet.
The truth is it would be logically absurd to boycott all nations, but that doesn't mean targeting Israel is therefore justified on the basis that one is better than none. Why not all the others?
It all comes back to Palestine being a popular cause that people love to latch on to. This is possibly a legacy of the radical generation of students from 1968, who took part in worldwide protests often called a "failed revolution" and went on to shape left-wing discourse in the years after.
Their upsurge was timed alongside the controversial and defining Six Day War in 1967, which saw Israel violently seize the Gaza Strip, Golan Heights and the West Bank and begin its occupation.
Now to be part of the in-group of certain radicals, leftists, revolutionaries and so on, you must first earn your anti-Israel badge and advocating a boycott is one easy way to do that. It also helps others to feel like they're doing something worthwhile in the face of terrible suffering.
It's a comforting stroke to the ego that is untroubled by the obvious problem that it doesn't actually work. Somethingmustbedoneism is tempting, but most often that something helps you more than it does anyone else.
One of the justifications for the boycott is that Israel is committing a violent form of collective punishment on the Palestinians living in Gaza because of the actions of Hamas militants.
While it is nonviolent by nature, the blanket boycott of Israel's academic and cultural institutions is its own form of collective punishment on ordinary Israelis. It seeks to remove academic freedom and cultural opportunities from the Israeli people because of the actions of their government.
It may lack the brutality of Israel's collective punishment of Gaza, but the fundamental principle that underpins it – penalising everyone for the actions of a powerful minority – is the same and so should be rejected out of hand by those who oppose what Israel is doing.
And there should be a case for greater cultural and academic work with Israel. Universities are cauldrons of dissent from which work can be done to help change the policies of the government at the top. We should be adding fuel to the fire underneath, not putting it out.
The same applies to culture. Poetry, art, music, literature – all of these are fertile soil from which beautiful things can grow from the seeds of satire and critique. Rather than salting the earth, radicals should be infiltrating Israeli culture and trying to bring about a change for the benefit of Palestinians.
On the business front, once again the argument for "more" holds most weight. With trade and investment comes influence. The more business we do with Israel, the more its economy relies on our money flowing into it, the greater power we wield when trying to bring about change. The carrot of investment if Israel's policies change followed by the stick of withdrawal if it steps out of line.
Take the US. It is criticised for funding Israel to the tune of billions of dollars a year and not cutting this back when the country is reckless, murderous even, in killing Palestinian civilians. And the truth is that if the US were to turn off the money tap it could probably end this current war and possibly even the blockade on Gaza.
But this possibility wouldn't even be on the table if the US was not invested in Israel at all. The fault lies not with money being pumped into Israel, but that the American government is not exerting its influence powerfully enough to stop the slaying of Gazans.
Support for campaigns to boycott Israel will never reach that sweet spot Marxist revolutionaries fantasise about: critical mass. Minor victories here and there will not lead to overall glory and a change in Israeli policy.
Noam Chomsky, a giant of left-wing thought and an arch-Israel critic, has himself expressed doubt about the efficacy of a boycott.
Writing in The Nation, Chomsky questioned comparisons made between the boycotting of Israel and that of apartheid South Africa. He notes that investment is still flowing into Israel and that international opposition is nowhere near the level it was to the racism of South Africa, where capital was pulled out and sanctions were applied long before the boycott.
Therefore the Israel boycott is doomed to fail because the current Israeli policies towards Palestinians will continue unaltered. In short, there will be no impact. Chomsky concludes that "those who are sincerely dedicated to the Palestinian cause should avoid illusion and myth, and think carefully about the tactics they choose and the course they follow."
Getting Israel to change its policies requires a multi-pronged approach. Engendering fierce criticism in culture and academia and using trade and investment for political leverage are two of those important prongs – and neither can be achieved by boycotting Israel.
Shane Croucher is a senior business reporter at IBTimes UK.