Generally speaking, people who write something know in advance what they are going to say, and not surprisingly, they agree with it. Along these lines, Hal Finney says in this comment:
Michael Ruse is quoted above as saying, “The God Delusion makes me embarrassed to be an atheist, and the McGraths show why.” That’s very much to his credit, that although he agrees with the conclusion of Dawkins’ book, he disagrees with the arguments. You don’t often get people willing to make these kinds of public statements that undercut arguments in favor of their beliefs.
Sounds like McGrath himself is a theist, unfortunately, so his book is arguing for a conclusion he believes in, as did Dawkins. And of course, as is true for virtually 100% of books every published. Can you imagine a book arguing page after page for the existence of God, written by someone who doesn’t believe in God? Or vice versa? Is it a sign of bias, that we never see that?
This isn’t so much a sign of bias, as an effect of a person’s goals. If someone thinks that something is true, he may want others to know that it is true. Normally he would not want others to think that it is false, which would be the expected effect of arguing that it is false.
Nonetheless, the fact that the writer knows where he is going can have bad effects. We saw that in the case of Spinoza’s ethics. But this can happen with anyone: if I am trying to make a point which is in fact false, then I will be likely to make fallacious arguments. Likewise, even if my point is true, but in reality I do not have very good reasons to think it is true, I will be likely to try to make my arguments look stronger than they actually are.
Despite such possibilities, however, the fact that I have a position and that I wish to persuade others gives me some reason to argue for that position rather than arguing for the opposite. Nonetheless, this results from my goal of persuading others. If my goal is to understand the truth myself, arguing one side rather than the other is not helpful: in such a case I should indeed argue both sides, as was done with disputed questions. In other words, the goal of making a point is different from the goal of understanding, and these goals require different means in order to accomplish them.
James Chastek comments on a similar issue:
All the pleas for dialogue I have heard came from the Left, and all of them beggar belief. However sincere the Leftist might be – and I’m not a mind-reader in any position to decide the question – I can’t get beyond the fact that the Leftist himself never follows his own advice by just giving the reasons of his opponents. Why give a speech that “calls for dialogue” when you could give a speech that presents, without comment or judgment, both your own reasons and those of your opponents? Why are calls for dialectic so reliably non-dialectical?
So you want dialogue? Great. You first. Explain the arguments of the other side without continually relating to them as things to be refuted. I can’t do this, even after many years of criticizing my own thoughts and trying to find real insights in opponents (each of whom are sure believe, with some justification, that my thoughts are far more narrow than they seem to me.)
The goal of making your point only requires that you be able to make arguments for your position, but the goal of understanding requires that you be able to make the opposing arguments as well. So if you can’t do this, there is likely a great deal lacking to your understanding of reality.
In the following posts, for illustration, I will argue both sides of various positions.