In 1886, a man called John Langdon Down asked a question that would be regarded today as politically incorrect. In his "Observations on the Ethnic Classification of Idiots", he showed that ' A very large number of congenital idiots are typical Mongols'.

In fact, he was using this observation as an argument against slavery:

If these great racial divisions are fixed and definite, how comes it that disease is able to break down the barrier, and to simulate so closely the features of the members of another division. I cannot but think that the observations which I have recorded, are indications that the differences in the races are not specific but variable.

His observation was also an important step in understanding Down's Syndrome and dealing effectively with those affected, resulting in less stigma of the condition. Needless to say, any allusion to 'mongolism' is studiously avoided modernly.

Political correctness itself is a recurring seeming contradiction in the pursuit of truth. In
order to properly care for a group, -- if you are honest about their welfare -- you must face their reality.

When an insult is issued, there may be truth behind it. The more important question to ask is why was the seeming insult issued? It leads to a line of inquiry and debate that leads to real investigation and thought about what action to be taken. You cannot even begin to decide what to do unless you have the facts. You cannot have the facts unless you verify observations and investigate any reasons behind them honestly.

These facts do not go away simply because we choose not to acknowledge them and bury our heads in the sand.

An example of a very controversial current topic is IQ differences between ethnic or racial groups. Yet, asking the question is important. The answer will of course be used by different factions to promote their agendas; that's no reason not to ask the question or acknowledge average differences in the first place. Only then can real debate and action happen examining why is it happening: to what extent is it genetic, disease-related, environmental, cultural or socioeconomic? What're the implications of this and does it matter to society? What are the solutions and do we need them?