Lack of knowledge

The "precautionary principle" requires that where there are significant risks of damage to the environment, precautionary action to limit the use of potentially dangerous materials or the spread of potentially dangerous pollutants is taken, even where scientific knowledge is not conclusive, if the balance of likely costs and benefits justifies it.

It is said that knowledge is a power. What is most of our boasted so-called knowledge but a conceit that we know something, which robs us of the advantage of our actual ignorance (Henry David Thoreau).