It’s admirable, perhaps even required, for those of us living comfortable lives in the developed world to give some time or money to ‘good causes’. We recognise fortune has smiled upon us and have a desire to ‘give back’ in some way – we have so much and others have so little, we seek to redress it.

But while there is strong agreement the fortunate have an opportunity – some would say an obligation – to use their resources to make life better for the less well-off, the discussion often ends here. That is, we think people should do something but we’re often not concerned with exactly what that something is. Should you donate to a local homeless shelter, a national medical research charity or a big international NGO? For many people, it’s unclear there’s any difference between these actions – surely they all make the world a better place?

Let’s think about that.

Say there were only two charities in the world, The Cupcake Foundation and the Real Actual Medicines Trust. The Cupcake Foundation distributes delicious cupcakes to people in hospital. The Real Actual Medicines Trust distributes medicines that will completely cure a patient’s disease. Both charities are undeniably making the world a better place but it’s pretty clear that one is doing much more good than the other. I think most people would choose to donate their money to The Real Actual Medicines Trust.

Asking these questions gets to the heart of why it is we help people. Are we altruistic because we think that making others better off is good in and of itself? Or do we just do it to stave off our middle-class guilt?

Take a different example. Let’s say that a third charity, Medicines ’R Us, is also distributing medicines, but they use generic medicines that cost half as much to produce as the on-brand medicines distributed by The Real Actual Medicines Trust. This means that a $20 donation to the Medicines ‘R Us will cure twice as many people as a $20 donation to the Real Actual Medicines Trust. Surely – given we can do twice as much good donating to the former than the latter – we should give our money to Medicines ‘R Us, thus doubling our impact.

These seem like contrived examples, but in reality, the differences between charities are astounding – not just a factor of two or three times, as in the example above, but some are ten, or even 100 times more effective than others!

Asking these questions gets to the heart of why it is we help people. Are we altruistic because we think that making others better off is good in and of itself? Or do we just do it to stave off our middle-class guilt? To impress other people? To show off?

Undoubtedly many good works are motivated by these latter factors. But are they really good reasons? Are they the reasons we’d choose? I’d certainly like to think that when I donate to charity I’m doing it for the benefit of other people. The sense of wellbeing that I get afterwards is nice but ultimately not morally important.

If it’s really other people’s benefit we care about, we need to think hard about how we choose where we spend our time and money on good causes. We don’t have infinite time and money. Every choice to donate something to one cause is an implicit choice not to donate it to another.

It might seem harsh to judge any charity less effective than any other another. Doesn’t that mean that the people served by the less-effective charity lose out? It does. But not making comparisons doesn’t mean everyone gets the help they need. It means that people who would be helped by the more effective charities lose out. More people are becoming sick, even dying, because people are choosing not to donate more effectively.

In the long run, hopefully we’ll be in a position to eradicate extreme poverty and disease from the world and we’ll have enough resources to fund all good causes. In the meantime, we should surely help as many people as we can.

Effective Altruism, a new social and philosophical movement is emerging to try to answer a fundamental question – “what is the most good that we can do?”

Effective altruism is about using evidence and reason to find ways to make the world as good a place as it can be. It tries to view all people – wherever they are in the world, even those not yet born – as being equally deserving of living happy, healthy, dignified, flourishing lives. Its proponents try to focus on the best ways of doing good. It’s just like regular altruism in that it seeks to do good for others. However, by focusing on effectiveness, it seeks to do the most good possible.

This manifests in different ways. Some people try to find the most effective charities to donate to, others try to work out which career you should choose if you want to have the biggest impact. Others think about the long-run future of humanity, reasoning that if there’s even a small chance that humans could wipe ourselves out (say, in a nuclear winter, or a deadly engineered disease escaping a laboratory), avoiding such an outcome would be a huge benefit.

It’s just like regular altruism in that it seeks to do good for others. However, by focusing on effectiveness, it seeks to do the most good possible.

Many also take a pledge to give a fixed portion of their income to effective charities – often 10 percent – because it increases the chance that they’ll actually donate, rather than putting it off for another day. In all these cases people are motivated by their sense of empathy but guided by scientific evidence and reason.

It may seem strange to think we might have an obligation to donate to one set of charities rather than others. After all, surely if someone wants to donate their money to a charity that focuses on people in their local community or on a cause that’s particularly important to them, they have that right. Of course, donation – unlike taxes – is an individual choice, not a legal obligation. But when faced with a choice of whether to help 100 people or just one, is it really a difficult decision?