Mike Huckabee is a creationist but says it doesn’t matter in his bid to become president, because “[he’s] not planning on writing the curriculum for an eighth-grade science book”.
Huckabee is wrong; it does matter.
Machiavelli wrote that a ruler should be wise himself, but if not he must be wise enough to choose good advisors. The world today is more complex than renaissance italy, so no one man can hope to know everything himself, and choosing good advisors is therefore essential.
But Huckabee has shown that he cannot do this: every serious biologist says humans evolved from other animals, and every serious geologist says the earth is billions of years old. If Huckabee cannot take their advice, because it contradicts what he wants to believe, he can never be relied on to choose wise advisors or take good advice.
As Bill Maher puts it:
“If someone believes that the earth is 6,000 years old and every scientist in the world is saying that it is billions of years old, why shouldn’t I take that into account when I am assessing the rationality of someone I am going to put into the highest office in the land?”