Reason: Evidence-Free Assertions and the Illusion of Rebuttal
When Conjecture Masquerades as Fact in the Absence of Argument
Sometimes trolls and pseudo-skeptics make what I call evidence-free assertions. That is, conjectures not labeled as conjectures - conjectures asserted as fact in attempt to rebut reasoned arguments. Does this conform to any known fallacy?
Yes—asserting conjectures as fact without evidence, especially to dismiss reasoned arguments—aligns with several known logical fallacies and rhetorical tactics. Here are the most relevant:
1. Assertion Without Evidence (Ipse Dixit / Bare Assertion Fallacy)
Simply stating something as fact without supporting evidence is a fundamental logical flaw. It is often phrased as "X is false" or "Y is true" without justification. This is the essence of an evidence-free assertion.
2. Burden of Proof Reversal (Argumentum ad Ignorantiam Misuse)
In rational discourse, the burden of proof lies with the person making the claim. If someone asserts a counterclaim without evidence, they are not actually rebutting anything—they are just making another unsupported conjecture. If they demand others disprove their unevidenced claim, they commit a burden of proof shift.
3. Straw Man Fallacy (if they misrepresent the argument first)
If the pseudo-skeptic misrepresents a reasoned argument and then attacks the distorted version with an unsupported claim, they are committing a straw man fallacy.
4. Dismissal by Fiat (a form of Dogmatism)
Declaring something impossible or false without engaging with the evidence is a dismissal by fiat—a rhetorical tactic, not a legitimate rebuttal.
5. False Skepticism / Pseudo-Skepticism
True skepticism involves critical evaluation of evidence. Pseudo-skepticism occurs when someone denies claims without examining the evidence and asserts counterclaims without support.
Summary:
Your description best fits the Bare Assertion Fallacy, with possible overlaps into Burden of Proof Reversal and Dismissal by Fiat. If the unsupported claim also misrepresents the original argument, it might be a Straw Man Fallacy. Finally, when this is done under the guise of rational skepticism, it qualifies as pseudo-skepticism.