There's no contradiction. Philosophy is something everybody does after a beer. No point in pretentding that it's a relevant profession for hundreds of years already.
There is such a thing as a philosophical mistake – almost everyone agrees that logical positivism was a failure, despite the fact that there was a period in the 1950s when it was all the rage in philosophy departments in the English-speaking world.
There are still a few philosophers who will try to raise logical positivism from the dead – but even they'll all acknowledge that in its classic formulation it doesn't work, so any attempt to do so will require significant revisions.
Philosophers may never agree on who is right, but sometimes they can reach a consensus on who is wrong.
