Argument of Lack of Evidence

An argument from lack of evidence to the contrary is a fallacy in informal logic. It says something is true because it has not yet been proven false. Or that something is false if it has not yet been proven true. This is also called a negative proof fallacy. This also includes the false assumption that only two options exist (true or false). There may be as many as four choices:

1. true
2. false
3. unknown
4. unknowable.[1]

Appeals to ignorance are often used to suggest the other side needs to do the proving. Rules of logic place the burden of proof on the person making a claim.[2]

A logical fallacy is simply a flawed argument.[3] Using bad logic does not necessarily mean the argument is false (or actual). It is a hasty conclusion, one that is arrived at incorrectly.[4] But it still may be convincing to some audiences.[4] This is why it is used in politics and advertising.

Examples

“This chemical is safe because no one has found any toxic effects.” This only “implies” that complete testing has been done. It does not say it has been tested “completely.”

“The individual has never spoken out concerning their views on high tension. We can safely conclude that they must be anti-high tension”. The argument from the ignorance fallacy can be used to dismiss a subject or to argue that it means the opposite.

“Of course, absolute registration is possible in screenprinting. How else could it happen?” (The argument from ignorance often takes the form of “how else could X happen, ” implying that because there is no other explanation yet known, the one being offered is correct.)

References

1. Philosophy 103: Introduction to Logic. Lander University. 2004. Archived from the original on 30 April 2009. Retrieved 13 June 2021.

2. Douglas Walton 2014. The burden of proof, presumption, and argumentation. Cambridge University Press, p. 197.

3. T. Damer 2013. Attacking faulty reasoning. Boston: Wadsworth, Cengage Learning, 53.

4. Jerome E. Bickenbach; Jacqueline M. Davies, 1997. Good reasons for better arguments. Peterborough, Ont.: Broadview Press, p. 208.