A blue and black dress was a sensation in social media last week. It became a raging controversy because of a photographic illusion that made the colors appear to be white and gold. But it is important to note that it got so much attention because people were almost evenly split between those who saw the dress as white and gold and those who saw it as blue and black. This uncharacteristic split allowed an important philosophical question to spill over into popular culture for a couple of days.
The question about the color of the dress is the question of how much of what we see in the world around us is a reflection of our unexamined assumptions. The people who responded that you could not tell the color of the dress because the camera had altered the colors were the ones who were ultimately correct. It should be humbling to see that that group was so much smaller than the groups who were indignant that everyone else did not see the dress in the same colors that they saw.
We could notice the hidden assumptions in this case because were so evenly split. But there are things we are equally sure about where we do not get the same opportunity to examine our assumptions. Often there is a consensus of opinion about what we are all seeing. Often the consensus is mistaken.