Argument from Ignorance, or argumentum ad ignorantiam:
Fallacious arguments from ignorance erroneously claim either that lack of proof must render a claim false, or that lack of disproof must render a claim true.
Despite its name this fallacy does not refer to being ignorant of the facts per se, rather it refers to an ignorance of alternatives and of what constitutes proof. This fallacy muddles the true-false dichotomy with the question of proof or disproof, and as such is a form of false dilemma where only two options are presented when several options exist. The ignored possibilities include false claim-not disproven, and true claim-not proven, while the implied dichotomy confines options to false claim-disproven or true claim-proven. If only the world of thought were truly so simple.
An example of this fallacious argument within intelligent [sick] design theory is embodied in the “irreducible complexity” claim that if evolutionary biologists cannot provide the demanded explanation for “specified complexity”, then evolutionary theory fails, further fallaciously implying or stating that biological evolution is not a fact, and still further fallaciously implying or stating that God (aka the ‘intelligent designer’) must be responsible for whatever biological mechanism is under debate. Such a concatenation of fallacies could fool only those who insist upon belief in a creator.
The more careful claim of a ‘intelligent [sick] design’ debater is that ‘intelligent [sick] design theory’ ought to be taught alongside science in the classroom. This is not a substantiable claim because nothing about ‘intelligent [sick] design theory’ qualifies it to be regarded as science. Merely disputing the content of science does not qualify as being science. While many ‘intelligent [sick] design’ proponents appear not to understand the true nature of science, pretentiously-named Fellows of the so-called Discovery Institute are mostly well enough educated that they ought to understand the advantages and limitations of scientific investigation.
Many creationists and ‘intelligent [sick] design theory’ debaters who display the argumentam ad ignorantiam logical fallacy do not make their reasoning explicit, such that the conclusion of truth or falsehood is merely implied, or the actual argument is buried in the wordiness typical of ‘intelligent [sick] design’ authors. Because ‘intelligent [sick] design theory’ authors write for a readership that is typically not well versed in science, writings on ‘intelligent [sick] design theory’ necessarily contain very lengthy explanations. However, wordiness can also be a technique of verbal obfuscation wherein an argument – and its inherent deficiencies of logic – are obscured by rhetoric.
When the reader is not well versed with the topic under discussion, he or she will have more difficulty in determining whether or not the writer has provided an accurate, authoritative, and complete account of the topic. When the conclusions drawn by the writer fit with the reader's preconceived notions or feelings about the topic, then the reader is at risk of being misled. Knowledge of the fallacies of logic can provide a short-cut to determining the difficulties with an argument. A single fallacy of logic does not necessarily render the conclusions suspect. However, a plethora of fallacies do indicate that the argument, and hence the conclusions drawn, are fatally flawed.