Pyrrho of Elis

All philosophers are confident that rational thinking is the road to truth. Except for Pyrrho of Elis, who entertained some doubts about the quest for knowledge.

He argued that we can not fully comprehend nature, do not know for certain whether a statement is true or false, and are unable to build an ethical system on so weak a fundament. People would be happier, he argued, if they gave up these useless intellectual exercises and postponed their judgment. The result was a conservative political philosophy, because Pyrrho recommended that, even though we had no moral absolutes, we should live by time-honored traditions.

The weakness of his system is, of course, twofold:

1. one can not postpone a judgment forever, because sometimes action has to be undertaken;
2. how can one be certain that certain knowledge is impossible?