logical-flaws

logical flaws

This page is for documenting logical flaws and fallacies that the microformats community has in particular encountered on microformats mailing-lists. This is not intended to be a comprehensive documentation of all possible logical flaws - there are other resources on the Web for that.

Author: Tantek

Absence of a negative is not proof

Statements of the form:

"I can see no good reason why ABC should stop XYZ"

... do not provide justification for XYZ.

Absence of objections is not approval

Statements of the form:

"I have heard no objections, therefore everyone must approve."

are false.

Absence of input/objections means no one else cares, it means something is not relevant enough to bother with. Thus absence of input/objections is actually a far harsher criticism than any specific objection. Thus topics which fail to raise input or objections can be considered a very low priority for the community.

Legally is meaningless from non-lawyers

Qualifications of the form:

"Legally, xyz".*

when made by individuals who are not lawyers and who thus lack the authority to make legal statements, do not add any semantics to the remainder of the phrase "xyz", and thus the expression "Legally, " is meaningless.

legal weight variant

Statements of the form:

"xyz doesn't carry much legal weight."*

when made by individuals who are not lawyers and who thus lack the authority to make legal statements, similarly are meaningless.

Assumptions of lack of foundation or justification

Responses of the form:

"That assertion is completely without foundation or justification."*

or:

"You seem to be making unsubstantiated assertions…" *

are themselves unfortunately without foundation and unsubstantiated, because the person making the response doesn't and can't know from what foundation or justification the assertion could have been made.

If you don't know the foundation or justification for someone's assertion, don't assume it doesn't exist, rather, ask for it, e.g.

"What is the foundation or justification for that assertion?"

Related

Here are a few general pages on logical flaws which you may find of some utility, no guarantee is provided as to their fitness/consistency. Evaluate them critically before using/referencing.

• sfdebris Logical Flaws
• Logic & Fallacies