Scott Walker stumbled on it during a trip to London. He and the rest of the 2016 Republican presidential field will face it repeatedly in the months ahead. So it would probably be best if GOP candidates prepared a quick and clear answer to the question, ‘Do you believe in evolution?’ They’ll have to use it a lot.

If they are like most Americans, Republican candidates believe God has guided the creation of the Earth and its inhabitants. That alone is enough to craft an answer that will both represent their beliefs and work in a campaign.