True, this is a different way of thinking from other animals, but it is still ultimately selfish in strict terms of competition and adaptation. Stephen Dolphindolphin delphis.demon.co.uk. Colin Tudge calls for the "testing of testable hypotheses" in studying behaviour ("Outrage at violence is the easy way", 14 July). But, counter to his social Darwinism, no genes have yet been found that code for anything as complex as altruism and violence Besides, all that genes give us are capacities. Whether and how these are developed depends on the environment we interact with and create. An Aristotelian approach to human nature and ethics looks for realisable capacities in behaviour as a basis for working out the necessary conditions of human flourishing.

This avoids the grave flaws of the Darwinian model - its "just so" stories, beloved by free marketeers, whereby any trait is "good" because it is assumed to have served some function conducive to the survival of its bearer. If Colin Tudge is right that psychology and sociology are arid, the reason is that they are trapped in an underlying framework which has reached its limits, and lack the conceptual coherence, insights and interdisciplinary links to transform it into a more perceptive, expansive and virtuous one.David RodwayLondon SW1. The pictures of Gerry Adams in the White House were taken to heart by the Unionists of Northern Ireland; thus the fierce opposition to George Mitchell as a chairman in the talks Official America is seen as pro-nationalist. I take all Neal Ascherson's case ("Only American troops can secure peace for Northern Ireland now", 14 July) save that of the identity of the troops, given that "foreign soldiers are still needed". Those troops have not only to be non-aligned, they have also to be positively accepted as such by both sides What a tremendous opportunity for the EU to help The EU is "clean".

It has never been easier to cut the cost of your phone bill. Competition for residential customers is so fierce there is a confusing array of ways to save money, and services are seemingly launched every month. BT has cut prices by pounds 1.3bn in three years and is committed to slashing at least another pounds 300m over the next 12 months, but it is still losing 50,000 people each month to cable companies offering telephone services. As these firms invest billions developing their communications infrastructure, other international telecoms companies such as AT&T and WorldCom of America are also entering the market, using BT phone lines. AT&T's Calling Service, launched this month for national and international calls, is just the first of a number of services for home users to be launched this summer.Users pay one of two flat rates on a national call, 7p a minute between 8am and 6pm or 3p a minute at other times That compares to 9.8p and 5.8p from BT.

With the basic service, which costs pounds 3.99 a quarter, when you sign up you also choose an area in the world to which you would like to make discount long distance calls - America, Asia, Australia/New Zealand or the European Union. For national calls, Mercury users pay 17.6p for five minutes, which is also cheaper than AT&T or BT.These providers of subscription services have focused on national and international calls, though AT&T says it can save you money if your regular BT phone bill is at least pounds 100 a quarter. But you can still save on your calls even if you do not make enough to want to sign up to a subscription service. Holders of a Visa credit card issued by Saga, the financial services and travel company, can save up to 23 per cent on national calls and 41 per cent on international calls. A customer spending between pounds 25 and pounds 34.99 would be credited with 30 free weekend minutes in Britain. AT&T offers a service with a higher quarterly fee for those who want cheap rates for more than one zone.As well as call rates and subscription fees (Mercury has a pounds 5.75 quarterly fee), comparisons are complicated by, for example, Mercury giving a 5 per cent discount on all calls made to five nominated numbers and between 15 minutes and two hours of free calls, depending on how big your bill is. If you are calling Paris, however, Mercury has the cheapest rate.