As Frank Furedi's excellent analysis argues, conspiracy thinking - "attributing the problems and misfortunes faced by individuals to some intentional malevolent behaviour" is on the rise. As many have noted (e.g. electorates are becoming ever more delusional ("give me public services, but not government or taxes"). Both kinds of foolishness are connected to a decline in an authoritative and widely shared 'common sense' about the-Way the World Works: history, science, politics, ethics. etc.
Common sense is essential to civilisation and collective political life. Without it we are on our own as we try to grapple with the meaning of our personal experiences. Do vaccines cause autism? How would you know? True, people do come together in associations to address these questions, and other important issues such as alien abductions, but they are rarely properly equipped for open and systematic examination, and have a tendency to become echo-chambers instead. When large numbers of people not only deny well-established facts, such as evolution or the holocaust, but insist on the existence of ghosts, aliens, black magic, and the forthcoming end of the world, one can see why they also seriously believe that the WTC attack was a US government conspiracy. No wonder no one is interested in the wonkish reality of sensible public policy debates on GM crops or government deficits if you think the world works like that! In Tanzania albinos are at high risk of being killed and ground up for magic potions. Extreme yes, but a clear consequence of what the failure of authoritative common-sense in a society looks like.
For common sense is a hard-fought achievement of civilisation and politics that must be continuously struggled for. It took a great deal of collective work, and some luck, to create the mass education and media, and the commonly acknowledged 'structures of authority' such as the press, academia, and government that underwrite the quality of a successful society's common sense. These institutions were the engine for the production of widely accepted truths, and also the widely respected means for critically engaging with and revising them (such as 19th century 'common sense' about women and non-whites). When they decay, or are suppressed, so is common sense. This was the case in the Soviet Union, and unfortunately still is in those misgoverned and/or autocratic states across much of the world where political power operates opaquely and corruptly and citizens have good reason for suspicion about what is really going on between whom (although not necessarily good information about the true state of affairs). Deep scepticism of official information may be a reasonable response in such circumstances, but the only solution is to work to support the institutions that can shine light on the machinations of the powerful and hold them to account.
Our small hominid minds tend to over-attribute agency to events; our small worlds of experience reduce our ability to objectively grasp and analyse the larger world, necessary for science as well as for wider ethical perspectives. These institutions allowed us to escape the cognitive trap of small-mind, small-world prejudice that all of us are prone to. They make possible not only greater wisdom for each of us, but also provide the foundational consensus on which yet further political progress and welfare improvement can build on. Consider the germ theory of disease discovered by the aggregate analysis of cholera deaths and leading to the collective political construction of vaccination and sanitation programmes that have saved millions if not billions of lives. Contrast that with homeopathy, which claims that water has a 'mystical memory' and sells itself on word-of-mouth recommendations and personal consultations.
But those 19th century structures of authority are in decline: universities have become subsidised over-producers of impenetrable arcana, mass-media is dying, and no-one trusts politicians anymore. The risk is that unless we can rebuild those institutions, or construct new ones more suitable for the 21st century, that great achievement will wither and decay, reinforcing that unfortunate inbuilt democratic tendency for egalitarianism of opinion to extend from the political to the factual. People will rely ever more on their gut instincts and what others in their small worlds say (Pat Robertson knows why Haiti suffered that earthquake) while the commonly agreed facts, and factual perspective, from which you could objectively judge and dispute delusional claims melt away.