One of the trials of being a human is that you can't trust other humans, at least not until you've got to know them, and sometimes not even then. People you meet may well be lovely altruists wanting to help you enjoy the lush bounty of life, but they could equally be scheming fiends trying to con you out of the family silver or sell you consumer junk that you neither want nor need.

All part of life's rich pageant, of course, and I wouldn't really want it any other way. But in the not-too-distant future there may be another way, whether I like it or not. It occurred to me as I was walking home one day, thinking about how the best applications of technology generally enhance communications between people. Think of e-mail, mobile telephones, online dating, discussion forums and so on. All of them help people to communicate with one another.

One of the best examples is eBay. Here the communication is between buyers and sellers, and is underpinned by a clever feedback system that, to a certain extent, allows trust to be gauged even between two people who have never met or done business in the past. After each transaction, the buyer and seller can give each other positive, negative or neutral feedback. Generally speaking, the higher the amount and proportion of positive feedback, the more likely that person is to be trusted in future transactions, even with complete strangers. It's not a perfect system, but it works.

So, I thought, can this trust-measuring feedback system be applied to other areas of life? With the ubiquity of mobile phones (most of which are now effectively pocket computers with powerful communications hardware), it should soon be possible. I'm thinking about a system in which every transaction you make with another person is logged, and feedback is recorded.

Some of these could be standard shopping transactions. That would be pretty easy to do, especially as mobile phones could start to replace credit cards as the preferred payment method within a few years. An extra key-press once you've finished buying your groceries could give both you and the shop-keeper appropriate feedback ratings.

The same could apply when you successfully buy a house or a car. You might even get monthly feedback ratings from your employer. Don't worry, though, you'd be able to give them feedback in turn. The whole basis of such a system would be its reciprocity; anyone who gives you a feedback rating has to accept that you can then do the same for them.

Such a system could extend to personal transactions, too, allowing you to rate friends, family and perhaps even sexual partners - again bearing in mind that they can do the same to you.

There would have to be checks in place to prevent abuse, and to stop people making deals to regularly give each other inflated feedback, but there are already algorithms in existence to do that, especially since each person would have a unique identity; their mobile phone number.

After a few years of use, this system might be able to weed out dodgy car servicing companies, lying politicians, dishonest bankers and other untrustworthy individuals. It would also take a lot of the excitement out of life, but credit reference agencies and businesses would love it, so it might not be such an unlikely fantasy after all.