I've really only gone through half the book, but I want to bring attention to some of the most common fallacies I have found in the book, so that you can familiarize yourself with them beforehand.
straw man fallacy.
A straw man is a component of an argument and is an informal fallacy based on misrepresentation of an opponent's position, twisting his words or by means of [false] assumptions.Essentially, the idea of the straw man is to make your opponent look foolish so that you give the appearance that you defeated their argument. I recently posted on Newt Gingrich answering a question about proselytizing religion in schools with remarks on teaching about the religious views of historical figures. He talked about a similar, noncontroversial, topic to avoid responding on the more controversial topic. The hope when making a straw man argument is that the observer will get too caught up in the response to notice that the topic doesn't match the question or, in the more typical case of taking on an opponents position, that the observer will be unfamiliar (or at least not familiar enough to catch the misrepresentation) with that position.
I'm not really quite sure how often the straw man appears in the book. There are some places that I am suspicious it is used, but those are cases where I am not familiar enough with the attacked position...which, again, it is such unfamiliarity that is the key to a working straw man.
false dilemma/dichotomy is essentially a situation where the options provided are incorrectly limited, most often to two, hence the typical usage of the word "dichotomy" to describe the fallacy (though "dilemma" is perhaps more appropriate since you can have more than two options).
[It]...is a type of logical fallacy that involves a situation in which only two alternatives are considered, when in fact there are additional options (sometimes shades of grey between the extremes). For example, "It wasn't medicine that cured Ms. X, so it must have been a miracle."As in the Wikipedia example, after the options are incorrectly limited, all options but one are eliminated. Using the example, a likely third option is that Ms. X's own body healed itself.
A typical example in arguing the diversity of life, which is relevant to the book, is that proponents of intelligent design/creationism attempt to disprove evolution in order to show that their idea is correct when, realistically, both could be wrong.
In the case of the book, they use the law of excluded middle to set up their false dichotomies. (Note that this Wikipedia page has a link to the "fallacy of the excluded middle," which directs you to the false dilemma page.) Essentially, the idea of the excluded middle is that something either is or is not something else; there is no third option. While, for the most part, the authors correctly use the law, what they fail to do is show that when something is not something else, there are other things it can be.
For example, the statement "A basketball is either a purple sphere or it is not a purple sphere; there is no third option." is a correct statement. So what is a basketball? It "is not a purple sphere." But you may be noticing that a basketball is actually a sphere, but the color is orange (with black striping). Well, orange is not purple, so the statement that a basketball is not a purple sphere is valid. The point here is that the "not" includes numerous other possibilities of what something could be...not only numerous other colors but shapes as well for this example. This is what the authors conveniently forget to point out. (Additionally, their examples aren't as obvious as mine, so if they don't tell you, someone not adept in logic may miss this point.) Much like how a straw man is used, the hope is that the reader will be oblivious to this fact in regards to the cases used in the book.
argument from ignorance is similar to the false dilemma; in fact, the two often overlap, so I won't spend too much additional time on this.
It asserts that a proposition is true because it has not yet been proven false, it is "generally accepted" (or vice versa)...
Argument from ignorance may be used as a rationalization by a person who realizes that he has no reason for holding the belief that he does.
A good example of an argument from ignorance comes from Martina McBride's song "Wild Angels." As my wife is a big Martina fan (and since this song is her main ringtone on her phone), let me add the long disclaimer that I don't care that the song has an argument from ignorance in it. It's a song; songs are generally more for entertainment than for making a legitimate argument. There are exceptions, but this song does not seem to be one of those. Additionally, the lyrics in some of the songs I listen to are pretty much incomprehensible. So, I have no right to bash the music other people listen to. And that's not what I'm trying to do; I'm just pointing out the fallacy as a matter of fact, not a condemnation of the song. (Avenged Sevenfold's latest single speaks of holding on to faith. Yeah, that's not something I'd support, but it doesn't keep me from enjoying the song.) OK, that's my disclaimer. Moving on, the song has lyrics that go, "[It] must have been wild angels... [W]hat else could it be?" First, the question at the end is rhetorical and implies that there are no other options (so not even a dichotomy). Second, though not stated, there is also the implication that one cannot prove that it was not "wild angels."
Confirmation bias is all too common when it comes to religious belief. (It's quite frequent in politics, too.)
Confirmation bias (also called confirmatory bias or myside bias) is a tendency for people to favor information that confirms their preconceptions or hypotheses regardless of whether the information is true.In short, any evidence that seems to confirm the hypothesis is recorded, while any evidence that could disprove the hypothesis is ignored. Such bias is the main reason people think prayer works. As PZ Myers has pointed out, the Texas drought should "be a good strong datum that prayer doesn’t work." (Prayer also tends to be non-falsifiable; if a prayer isn't answered, for example, it might mean that "wasn't part of God's plan." Non-falsifiable hypothesis are automatically bad hypothesis.)
In the image above*, the "creationist method" is bound to be plagued with confirmation bias. After all, you need to start out with a conclusion to confirm to have confirmation bias. There are a number of cases of this in the book. Some are less obvious, but there is one good example (and it made my jaw drop when I read it) where they admit that the conclusion is more important than the facts. Heck, I'll jump the gun and add it here:
...[T]he more important point is not when the universe was created, but that it was created. - p. 165The "when" is in reference to the age of the universe (and earth). They are saying that the data (the age of the universe and earth) is less important than the conclusion (that the universe and earth were created by their god). This is backwards as far as science goes. (And as a quick preview of the preceding chapters, they were attempting to show that science was on their side. Yet, they end that block of chapters clearly demonstrating their poor grasp on science.)
* UPDATE: I do need to be honest and say that science does not always (actually, probably not even frequently) works as depicted in the image. There are many times when scientists will look at the facts they have and make speculations as to what the conclusion could be. This is often because all the necessary facts to draw a conclusion are not available. So scientists make the best of what they have. This is still much better than the creationist method that is depicted. Because, first, scientists are often honest about when they are just speculating and, second, because scientists then go out looking for facts to either confirm or disprove their speculations. /UPDATE
Those are the major fallacies I can remember being in the book at this point. If I find more, I'll discuss them as I find them. Otherwise, I'll typically refer back to this post.
With Halloween coming up, I'm not sure how much time I'll find to write about the book, but it's going to be near the top of my blogging priority list.