Is there a optimal number of friends that one person should have, to make their life fit together perfectly?
With the advent of Facebook and MySpace, actually counting the number of friends and acquaintances in your circle has become a realistic possibility.
The Today programme asked two friendly thinkers to outline their arguments on the numbers of our nearest and dearest.
DUNBAR'S NUMBER by PROFESSOR ROBIN DUNBAR
The number of people with whom you can hold personal relationships is limited to about 150 individuals.
This limit is set by the size of our brains, and fits a general pattern relating brain size and social group size across the monkeys and apes.
Relationships survive only if you reinforce them by occasional face-to-face contacts
Prof Robin Dunbar
It is important to remember that this includes your biological relatives as well as more casual acquaintances, but it does define the people with whom you have reciprocal relationships of trust and obligation.
It demarcates those whom you know as individuals from those whom you recognise but only have casual relationships with.
This circle of 150 is not an homogenous social group: it consists of four layers, the Circles of Acquaintanceship, which scale relative to each other by a factor of three (an inner core of five intimates, and then successive layers at 15, 50 and 150).
With each successive circle, the number of people included increases but the emotional intimacy decreases.
Although there has been a fashion for competitively adding 'friends' to one's social network internet site, in fact most people's social network sites contain only 100-150 names, and of these most exchanges are directed at the small inner core.
This seems to be because, ultimately, relationships survive only if you reinforce them by occasional face-to-face contacts.
Professor Robin Dunbar is the head of Oxford University's Institute of Social and Cultural Anthropology and the author of How Many Friends Does One Person Need?
COUNT ON THEM, DON'T COUNT THEM by MARK VERNON
The thing that worries me about saying you need 150 friends, or whatever number science decides it should be, is it turns friends into items for consumption.
Feeling that you are being used by a friend is something very different - the first sign of its terminal decline
"How many?" is a perfectly sensible question to ask when buying apples at the supermarket. But we form friendships with people.
They are I-Thou relationships, as Martin Buber put it, not I-It. Turn an I-Thou into an I-It, and you risk killing friendship stone dead.
It's like taking agony aunt advice from accountants; loving by cost-benefit analysis. My friends become the service providers in my optimized life - one to laugh with, one to cry with; one to have fun with; one to tell my deepest secrets.
It's clearly the case that everyone likes to be useful to their friends. But feeling that you are being used by a friend is something very different - the first sign of its terminal decline.
Mark Vernon is the author of The Philosophy of Friendship.
Does your quality of life depend on the number of friends you have, or the quality of the friendships you are part of? Let us know using the form below, or join the debate on Twitter.
Common sense would tell that real friends are not the same as Internet social networking friends. People really shouldn't get this confused. For sure we have very dear friends who are not even on any Facebook or Twitter. Laura, Devon via email
Friends are people you like and know. It's about choice not need. It isn't quantifiable like "how many eggs do I need to buy today?" damlucky via Twitter
Friends- companion, confidant, soul mate, alter ego, playmate, ally, associate, pal, playmate, ally, ally ... one of each? elpidageorge via Twitter
In real life; just a few good ones. On Facebook and Twitter; as many as you can possibly get. DavidKeech via Twitter
The BBC may edit your comments and not all emails will be published. Your comments may be published on any BBC media worldwide.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.