As you know, when we practice metta we direct lovingkindness to all beings and especially to those who are suffering. Now, if non-Buddhists were to ask me what metta is, I would point them to the metta sutta. And if they were to ask me why I practice metta bhavana or what I hope to achieve when I practice metta bhavana I would tell them that it is a means for me to cultivate wholesome states of mind and to promote wholesome volition. I think it shouldn't be too hard to explain to them the aims of metta in this way.
But in the case where I'm directing metta to someone specific, to someone who is experiencing difficulties, how does one explain the practice?
If someone were to say, 'OK. I can see how you practice metta to cultivate wholesome state of mind. I can accept that. But how does your practice actually affect someone else, especially someone whom you do not have direct contact with? How would your practice actually benefit the person whom you are directing metta to? How would it actually alleviate that person's illness or circumstances or whatever? Are you suggesting that metta would actually generate some kind of cosmic energy that would somehow 'touch' that person in question? If you choose to talk about Buddhism in term of its 'scientificity', in terms of its pragmatism and rationality, how then would you explain this supposed beneficial and helpful effect of directing metta to others, something which cannot be 'verified'?
I'm not quite sure how I would respond to these questions. In fact, to be honest, whilst I practice metta everyday and whilst I would direct metta to people I know who are suffering (e.g. just recently when Retro was in the hospital), I wouldn't know how to explain it to others. I mean I can of course explain it in terms of how metta helps me cultivate wholesome states of mind but how would I explain its supposed effect on others?
Perhaps these questions miss the point of metta. But they would not be unreasonable questions for non-Buddhists to ask. How would you respond?