Dr Paul Thomas of DNA Wales and Director of the Welsh Research Unit for Governance & Leadership has a great signoff quote from John Milton, with a neat bit of editing to avoid 17th Century sexism:

Where there is much desire to learn, there of necessity will be much arguing, much writing, and many opinions; for opinion in good [wo]men is but knowledge in the making

If something matters, it is worth arguing about; consensus is for the ordinary and inconsequential things of life. Of course it does need good [wo]men if argument is not to degenerate into bitter polemic. Exploring ideas, supporting a position you do not necessarily believe in to test an argument, taking a contrary view for the sake of argument are all mechanisms by which human knowledge can advance. I remember from my own childhood that the dinner table was a constant source of debate on a broad range of positions. If we (the family) were not sure of you, then we were polite. If we liked you, then we argued with you. It was a great environment to grow up in and one too sadly missed in the over facilitated, over homogenised world in which honest disagreement seems to be outlawed and all opinions considered of equal value.