There's no way that Richard Dawkins, or anyone else, could know what 45% of Americans actually believe. That figure might be based on some survey or poll, but that simply means that a bunch of people gave a certain answer to a question on a form.
Ummm. That is what a survey is. You ask people to answer questions on a form and use statistical analysis to generate a general idea of what the majority of people believe. It is precisely because a bunch of people gave a certain answer to a question on a form!
Polls have a use, though we need to be very careful about the results depending on a bunch of factors including:
1. Who is doing the polling? I.E. do they have an agenda in coming to a specific answer, or are they attempting as best as possible to be unbiased.
2. What are the questions in the poll. How questions are phrased make all the difference in what kind of responses one gets. Ideally when I see the results of a poll, I want to see the questions that were asked in that poll.*
3. What is the sample size and how well represented is the public overall within the sample size.
4. What is the margin of error. Which includes both how much accuracy can the poll predict, as well as how honest are people likely to be in their answers.
There are more; those are the important ones. For me personally, I am rarely impressed with any one poll. It is far more discerning to view the polling data from a reputable pollster over time. The more one gets similar results time and time again, the more likely the polling is likely to be accurate.
*A great old saw, which might even be apocryphal but which I still think is an excellent example (as well as one of my favorites). Two men are arguing whether it is appropriate to smoke while praying. So they each went to their pastors and asked the question. The two responses only confused them the more because they got one 'yes' it is appropriate and one 'no' it isn't.
Then they compared their questions.
The first asked his pastor is it okay to smoke while praying? And the pastor said "Of course not! Praying is serious business, you should not be smoking".
The second asked his pastor is it okay to pray while smoking. And that pastor said "But of course it is appropriate. Prayer is appropriate no matter whatever else you are doing".
