"But it is no good using the tongs of reason to pull the Fundamentalists' chestnuts out of the fire of contradiction. Their real troubles lie elsewhere"

This quote by Garrett Hardin is a metaphor for the problem of attempting to utilize logic and factor to persuade Fundamentalists of something that opposes their beliefs. Hardin is recommending that it is useless to try to use factor to persuade Fundamentalists of something that breaks their beliefs, as their genuine issues lie in other places. He is suggesting that the real concerns are not necessarily sensible or logical, but rather psychological or ideological. He is recommending that the only way to truly persuade Fundamentalists of something is to address the underlying issues that are causing them to hold onto their beliefs. Hardin is indicating that it is inadequate to just use reasoning and reason to attempt to convince Fundamentalists, as their real problems lie elsewhere.