Tuesday, April 16, 2013

Debunking Douglas Groothuis' Argument

On April 5, 2013, Jeff Shallit pointed out a blog post by Douglas Groothuis, a Professor of Philosophy at Denver Seminary. Prof. Groothuis' post was entitled "A Moral Case Against Darwinism". Here is an executive summary of Prof. Groothuis' argument.
  1. If evolution is true, then there is no philosophical basis for objective and universal human rights
Admittedly, the full argument is longer, but unnecessarily so, in my opinion. I actually agree with that statement.

But then he continues, asserting that statement (1) above is false. What I think he means is that the conclusion is false, since he says there IS a philosophical basis for objective and universal human rights.

And according to the rules of logic,
Given A->B
And ~B
We conclude ~A
In other words, the premise evolution is true is incorrect, and we conclude that evolution is false.

His rationale for rejecting the conclusion is that
Our moral intuitions and the history of Western law treat every human being, irrespective of race, as possessing intrinsic human dignity and must be treated as such.
It's true, we tend to have such intuitions and laws. But it does not negate the conclusion. Laws about equality are not a definitive philosophical basis for objective and universal human rights. Such laws can exist despite there being no philosophical basis.

And that leads me to my second point. Prof. Groothuis actually claims that an if-then statement is false. The logical negation of an if-then statement A->B is (A and ~B). That is, A is true, but B is false. This is basic logic.

Negating statement (1) means that evolution is true and there IS a philosophical basis for human rights.

However, I highly doubt that's what Groothuis means, since he's trying to show that evolution is false.

I submitted a comment to his blog, but unfortunately Prof. Groothuis said he "can't find the comments to post them". I guess things have changed since January 17th when he did post the comments on his blog.

So I thought I'd help him out by posting my own critique on my own blog. I wonder if Prof. Groothuis will respond on his blog?


  1. Unbelievable. Douglas Groothuis published a comment, but it was to a Portuguese translation of his post. So he DOES know how to publish comments... when they suit him. I must conclude that he is a liar.

  2. This shouldn't surprise you. Groothuis is not interested in anyone who takes issue with his poorly-reasoned posts.

  3. I wouldn't expect much from Groothuis. He is more interested in ignoring people who disagree with him. I called him out on the logical imprecision of many of his facebook posts and he ended up blocking me and then attacking me when I was not able to respond. This kind of strategy allows him to preach to his little choir and brag about how smart he is without worrying about people refuting his sloppy utterances.