For the past two years, a mysterious disease has been wiping out honeybees in the US and Europe. This catastrophe could have a devastating effect on our food supply: about a third of the human diet comes from insect-pollinated plants, and the honeybee is responsible for 80% of that pollination. This is how one should imagine a possible global catastrophe: no big bang, just a small-level interruption with devastating global consequences.

There is an air of mystery to this mass death. Although the same thing is happening all over the developed world, local investigations point to different causes, such as the poisonous effects of pesticides, or the loss of the bees' sense of spatial orientation caused by the electronic waves of our communication machines. The multiplicity of causes makes their links with any effects uncertain, which invites the temptation to look for a deeper meaning and consider the so-called "spiritual ecology": is a beehive not a kind of slave colony, a concentration camp where bees are ruthlessly exploited? What if Mother Earth is punishing us?

The best antidote to this spiritualist temptation is to bear in mind the lesson of Donald Rumsfeld's theory of knowledge - as expounded in March 2003, when the then US defence secretary engaged in a little bit of amateur philosophising: "There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know." What Rumsfeld forgot to add was the crucial fourth term: the "unknown knowns" - things we don't know that we know, all the unconscious beliefs and prejudices that determine how we perceive reality and intervene in it.

In the case of the disappearing bees, there are things we know that we know (their vulnerability to pesticides) and things we know that we don't know (say, how the bees react to human-caused radiations). But there are, above all, the unknown unknowns and the unknown knowns. There are dimensions of how bees interact with their environs which are not only unknown to us, but which we are not even aware of. And there are many "unknown knowns" in our perception of bees: all the anthropocentric prejudices that spontaneously colour and bias our study of them.

The most unsettling aspect of such phenomena is the disturbance in yet another type of knowledge, in what the French psychoanalyst Jacques Lacan called "knowledge in the real": the "instinctual" knowledge that regulates animal and plant activity. This can run amok. When winter is too warm, plants and animals misread the hot weather in February as the signal that spring has began and start to behave accordingly, thus not only rendering themselves vulnerable to late onslaughts of cold, but also perturbing the rhythm of natural reproduction. Something of this kind is probably happening to bees.

We pride ourselves for living in a society in which we freely decide about things that matter. However, we are constantly in the position of having to decide about matters that will fundamentally affect our lives, but without a proper foundation in knowledge. This is frustrating: although we know that it all depends on us, we cannot predict the consequences of our acts. We are not impotent but - quite the contrary - omnipotent, without being able to determine the scope of our powers. While we cannot gain full mastery over our biosphere, it is in our power to derail it, to disturb its balance so that it will run amok, swiping us away in the process.

· Slavoj Zizek is international director of the Birkbeck Institute for the Humanities

szizek@yahoo.com