One of the things I like about sciblogs is that the bloggers here allow dissenting comments to be posted on their blogs. I think there are some very good reasons for allowing all but the most obnoxious or incoherent comments.
First, dissenting views can provide me with new information, which I can compare to what I already know about a topic. Usually a little research shows that the new information is erroneous or cannot be substantiated, however, occasionally something useful and or interesting can be found. A tiny bit of wheat amongst the chaff, which may be worth investigating further.
Second, dissenting views allow me to examine how easily science can be misunderstood. In my experience many problems come from the cherry picking of data, accepting the word of dubious “experts”, belief in scientific conspiracies, accepting the emotive over the rational and a general misunderstanding of what science is all about.
Over at Grant’s recent post on “should children be sent home from school if they aren’t vaccinated“, one rather zealous antivaxxer has bombarded the site with various dubious arguments against vaccination. As well as demonstrating all of the problems I describe above, this persistant antivaxxer also engages in what is sometimes referred to as the Gish Gallop – a technique that involves bombarding one’s opponent with a torrent of half-truths, unsubstantiated beliefs and strawman arguments. When another poster effectively counters one of his arguments he seldom replies other than to shift his argument from one point to another (commonly referred to as “shifting the goalposts”).
Third, only by exposing and countering erroneous and anti-scientific ideas can we help to provide the public with a better understanding of science. Ignoring or suppressing them only allows them to fester. Many anti-scientific posters cannot maintain their arguments for long in the glare of scientific questioning, and may devolve into insults, further giving the reader a true measure of their position (or lack thereof).
Compared to the majority of scientific sites many anti-scientific sites will block dissenting views, allowing their members to wallow in intellectual stagnancy and to indoctrinate new members into their cult of ignorance. Yet, these are the same sites that complain about their ideas being suppressed. How ironic.