The precautionary principle is: Actions should be taken to prevent damage to the environment even in cases where there is no absolute proof of a causal link between emissions or activity and detrimental environmental effect. Embedded in this is the notion that there should be a reversal of the “burden of proof” whereby the onus is now on the operator to prove that his action will not cause harm rather than on the environment to prove that harm (is occurring or) will occur.
Translation: Even if you don't know something will hurt the environment, you should take steps to prevent something like that from happening. It is our responsibility to show that what we do will not hurt the environment, rather than wait for the environment to show that it was harmed.
Do you accept or reject the precautionary principle? In other words, should those who wish to introduce a new chemical, a new industrial process, a land-use change, and so on, have to demonstrate that their change will not harm the environment before proceeding? Explain and defend your answer.