What, in your opinion, would it take to cause civilisation as we know it to collapse?

Nothing really, Honestly, I feel that our civilization will collapse if we keep going the way we are. Our consumerism and drive for "more" causes us to be really careless when it comes to matters such as the environment, and properly estimating how much of a resource there really is. Just by consuming more and more we eventually create a deficit in the world of a certain material/product/resource and eventually our civilization will have to change to accommodate that (or else completely fall apart). Currently, ideas such as renewable energy sources are being researched, and there is more and more emphasis on recycling... while this might not be the collapse you are looking for when you asked your question, our society is slowly changing and changing (collapsing SLOWLY and rebuilding). I'm hinting that this is the collapse of our civilization because I really feel that after the next 50-100 years, our society/culture/civilization will be drastically different, or it won't exist at all.

What are some of the pillars of society and some of our biological necessities? Food, water, and a climate capable of sustaining us. Would something that destroyed the credibility of our science or religion be enough to undo us? Perhaps. It depends on what it was. If aliens from another world visited all the world leaders simultaneously that would certainly shake things up. Both science and religion would have some explaining to do, LOL, but we would still survive.

I think it would take some catastrophic event that irreparable damaged our ecosystem or a chasm in reality like proof that matter is only a construct of the mind.

Well, That depends on the degree of collapse you are considering.

Joseph Tainter "The Collapse of Complex Societies" and then decades later Jared Diamond's "Collapse", is a good examination of some of the factors for a few of the more well known civilizations known to have collapsed in some very near catastrophic way; i.e.; the Incas/Aztecs (Disease/ Invasion), Mongol (Imperial overstretch), Spain (twice), Military/Imperial Overstretch, Germany (twice), Military/Economic Overstretch, France , Military Overstretch, Russia (twice), Military Overstretch/Bad Industrial Policy.

Basically, MANY civilizations have collapsed in very real senses relative to their previous importance , but managed to recover, some - like the Aztecs or Prussian Empire or Austra-Hungarian Empire fell to a variety of internal factors and failures to manage the problems.

The United States, currently has MANY of these challenges, economic imprudence over multiple administrations, extensive military overstretch since the 1960's, and new but by no means less concerning is social overstretch.

MANY current economies, including the United States, Japan, Germany, Italy, France, England are not fiscally well balanced in light of the demographics of their respective societies.

Japan is clearly the most acute of these , with an aging population, restrictive immigration policies and a childbirth rate that is catastrophically low, Japan faces fiscal concerns well into the late 21st century.

Ironically, the United States is not as bad off as many other states, in some respects , but our failure to address some potential failure points over literally decades is not encouraging.

Globally, there are a number of concerns, basically centered around resource consumption.

The most pressing general problem that everyone can relate to , is fuel/energy and specifically Oil and our inability to effectively form and follow policies that put the US in a better position as oil becomes increasingly scarce.

I however, would say that those systemic problems aside there are also "event" type problems which we also do not plan properly for.

So in order, here are what I would consider the top threats to our modern / integrated civilization.

Wildcard events - While these first two items are "wildcard events" in that they may not necessarily occur, as a collection of nation states, we DEFINITELY do not do enough to police and reduce the risk of these events occurring.

1. Nuclear war / terrorism - In simple terms in less than 2 generations the most dangerous weapons available to our species have become the fetish object of some of the least responsible organizations on the planet. - http://video.google.com/videoplay?docid=-486459270...

The systemic problems associated , even with a limited nuclear attack could EASILY cause disruption at the least, and collapse at worst - due to EMP effects, whatever nation is targeted (save China or India) would certainly be knocked down a peg or two economically.

2. Biological weapons - while most of the biological stock of the former USSR have degraded, the stocks are still present and could be reconstituted rather easily - security being systemically low, and damage significantly more regional and less likely to go "out of control", means bioweapon attacks are likely to be a recurring theme of the 21st and perhaps 22nd century - the worst case - of course is a type of 12 monkeys scenario involving more advanced genetically tailored/designed weapons - http://www.youtube.com/watch?v=CBNMEwNx9x4

While these first two are both probable in some form due to our negligence regarding weapons proliferation and hypocrisy, I suspect we might straighten up the first time 100 or 200 thousand people get nuked again.

3. Peak Oil - this is not just a likely cause of civil collapse it's a geological certainty. While I would fully expect that given the resources and technological advances of 100 or 200 years we could easily develop a small efficient and cost effective replacement for liquid petrol fuels, there is nothing on the horizon that provides such high energy density as oil. The US has (like a child defiant who dislikes broccoli) avoided any serious efficiency efforts or repositioning of our economy away from near total dependence on oil. http://www.youtube.com/watch?v=3sPDNR2YS3s

So right now something like 80% of our economic growth is absolutely tied to oil use. Countries like Sweden, Germany and Japan have vastly more aggressive transition programs an excellent public awareness and education in the effort to move to other energy sources, and are nearing the 60% mark to GDP presently.

4. Economic Collapse - Simply put - our political class can't add and feels little to no REAL serious responsibility , so while the theme of the day over in the politics section is to evicerate the democrats or republican on this or that policy, BOTH parties fail historically speaking to be respo

"If electricity was eliminated completely. Among the many things electricity runs is the security systems in all our prisons. So all of a sudden the doors would fly open and out would come all of our old friends, the ones who've been away at camp, maybe dropping by your home." - George Carlin

A global nuclear war! It's just a matter of time before our tendency to push each other around would finally doom us out of existence.

There are 3 most likely places where WW III will begin: Israel, Taiwan or Kashmir.

Morality. Once people become moral, civilization will collapse like a Haitian building during an earthquake. Luckily, this will never happen.

When humour, poetry, art and spirituality have been scarified that will be the end of civilisation as we know it.

Delilah actually managing to get to level 7 :)

To lose all enforcers of the law (police) and have no law to have to follow and a system to keep a person in order.

financial failure as we are experiencing now! *ok so maybe the bleeding has stopped yet there remains a gaping wound, and to disclaim it may be fully stupid and irresponsible!