I was just thinking about how empathy seems to be in short supply these days. But then I consider the response from ordinary people to the plight of refugees from Africa and the Middle East. Money is being donated and shelter is being offered by families and individuals with no connection to those in need. So what drives this outpouring of charity?

No doubt there are many factors but I think the main one is empathy - the ability to understand and share the feelings of another. Faced with images of desperate people on the news every night, most of us ask ourselves, "How would I feel if I were in that situation?" And that experience of stepping into their shoes is so painful and frightening that you simply have to take action.

But that's not the only response that's elicited by the "migration crisis". Many people in Europe are afraid of large numbers of foreigners coming into their countries and don't want to meet the cost of supporting them. They say things like, "I'm sorry, we've just got to be realistic. They'll have to go back."

You see a similar divergence in attitudes (in the UK) to state benefits given to the unemployed and poorly paid. Some of the well-paid and comfortably off taxpayers see the poor as victims who need help whilst others see only "scroungers", out to get what they can and playing the rest of us for fools.

In both the cases of refugees and of benefits recipients, there can be a positive, supportive response from others that I suggest stems mainly from empathy with people perceived to be in trouble. "If I were in that position I'd want someone to help me."

So what drives the other response of resistance or even hostility?

First of all, there's an obvious self-interest factor: helping others involves material costs and our selfish selves want to keep our money and our comforts. This is perfectly normal and is probably an evolved behaviour that helps ensure survival in a competitive environment.

But we have also evolved the capacity for altruism towards our families and our close social groups. This is explained by the fact that we share genes with our relatives and it's the genes that evolution propagates, irrespective of individuals' interests. So maybe the ability to empathise is part of that process, being the mechanism that our genes have come up with to ensure that we maximise their (the genes') chances of survival.

So, if we have this tendency to feel empathy for our fellows in trouble, how is it possible for some of us to ignore it?

It appears that we can choose to switch off empathy in any given situation, presumably when there is a stronger, competing emotion. For example, empathy can go out of the window in extreme survival situations when you panic and can only think of saving yourself. But the impact on us of helping refugees or the poorest in society is hardly in that league, so we must have a way of switching off our empathic concern for others in less threatening circumstances.

Last month I talked about using "coping strategies" to deal with mental overload, and it seems to me that desensitising yourself to how others are feeling, so that you can ignore their need, is just another coping strategy. It's how you deal with the demands of other people when you feel you can't meet them.

If that's true, then it leads to a very interesting position for those of us who condemn the selfishness of all those who turn their backs. We have to look at what they do as a sign of their own shortcoming - their lack of the unconscious thinking pattern that can reconcile the conflicting impulses they feel. Their only possible response is to switch off their empathy.

Can you imagine yourself in that position? Can you empathise?

So, who should we feel sorry for now? (That's sympathy by the way, not empathy.) And why bother?

As I've explained, the ability to understand and share the feelings of others has been a factor in human survival. We can ignore it under stress and many of us do - but you have to think that there's a cost to doing that. John Donne summed it up in the 17th century:

No man is an island,
Entire of itself,
Every man is a piece of the continent,
A part of the main.
If a clod be washed away by the sea,
Europe is the less.
As well as if a promontory were.
As well as if a manor of thy friend's
Or of thine own were:
Any man's death diminishes me,
Because I am involved in mankind,
And therefore never send to know for whom the bell tolls;
It tolls for thee.