Philosophic burden of proof
Holder of the burden
When two parties are in a discussion and one asserts a claim that the other disputes, the one who asserts has a burden of proof to justify or substantiate that claim.  An argument from ignorance occurs when either a proposition is assumed to be true because it has not yet been proved false or a proposition is assumed to be false because it has not yet been proved true. This has the effect of shifting the burden of proof to the person criticizing the proposition.
While certain kinds of arguments, such as logical syllogisms, require mathematical or strictly logical proofs, the standard for evidence to meet the burden of proof is usually determined by context and community standards and conventions.
In public discourse
Burden of proof is also an important concept in the public arena of ideas. Once participants in discourse establish common assumptions, the mechanism of burden of proof helps to ensure that all parties contribute productively, using relevant arguments.
Proving a negative
A negative claim is a colloquialism for an affirmative claim that asserts the non-existence or exclusion of something. There are many proofs that substantiate negative claims in mathematics, science, and economics including Arrow's impossibility theorem.
A negative claim may or may not exist as a counterpoint to a previous claim. A proof of impossibility or an evidence of absence argument are typical methods to fulfill the burden of proof for a negative claim.
Matt Dillahunty gives the example of a large jar full of gumballs to illustrate the burden of proof. The number of whole gumballs in the jar is either even or odd, but the degree of personal acceptance or rejection of claims about that characteristic may vary. We can choose to consider two claims about the situation, given as:
- The number of gumballs is even.
- The number of gumballs is odd.
Either claim could be explored separately, however, both claims represent the same proposition and do in fact ask the same question. Odd in this case means "not even" and could be described as a negative claim. Before we have any information about the number of gumballs, we have no means of checking either of the two claims. When we have no evidence to resolve the proposition, we may suspend judgment. From a cognitive sense, when no personal preference toward opposing claims exists, one may be either skeptical of both claims or ambivalent of both claims.  If there is a claim proposed and that claim is disputed, the burden of proof falls onto the proponent of the claim. If there is no adequate evidence to support a claim, the claim is considered to be an argument from ignorance.
- Legal burden of proof
- Scientific consensus
- Scientific method
- Statistical hypothesis testing
- Russell's teapot
- Cargile, James (January 1997). "On the Burden of Proof". Philosophy (Cambridge University Press) 72 (279): 59–83. doi:10.1017/s0031819100056655.
- "Argumentum ad Ignorantiam". Philosophy 103: Introduction to Logic. Lander University. 2004. Archived from the original on 30 April 2009. Retrieved 2009-04-29.
- Dowden, Bradley. "Appeal to Ignorance". Internet Encyclopedia of Philosophy.
- Michalos, Alex (1969). Principles of Logic. Englewood Cliffs: Prentice-Hall. p. 370.
usually one who makes an assertion must assume the responsibility of defending it. If this responsibility or burden of proof is shifted to a critic, the fallacy of appealing to ignorance is committed.
- Leite, Adam (2005). "A Localist Solution to the Regress of Justification". Australasian Journal of Philosophy 83 (3): 395–421 [p. 418]. doi:10.1080/00048400500191974.
[t]he point of articulating reasons in defense of one’s belief is to establish that one is justified in believing as one does.
- Leite, Adam (2005). "A Localist Solution to the Regress of Justification". Australasian Journal of Philosophy 83 (3): 395–421 [p. 403]. doi:10.1080/00048400500191974.
justificatory conversation...[is]...characterized by a person’s sincere attempt to vindicate his or her entitlement to a belief by providing adequate reasons in its defense and responding to objections.
- Goldman, Alvin (1994). "Argumentation and Social Epistemology". Journal of Philosophy 91 (1): 27–49. doi:10.2307/2940949. JSTOR 2940949.
- Eemeren, Frans van; Grootendorst, Rob (2004). A Systematic Theory of Argumentation. Cambridge: Cambridge University Press. p. 60. ISBN 0521830753.
[t]here is no point in venturing to resolve a difference of opinion through an argumentative exchange of views if there is no mutual commitment to a common starting point.
- Brandom, Robert (1994). Making it Explicit. Cambridge: Harvard University Press. p. 222. ISBN 067454319X.
[t]here are sentence types that would require a great deal of work for one to get into a position to challenge, such as 'Red is a color,' 'There have been black dogs,' 'Lighting frequently precedes thunder,' and similar commonplaces. These are treated as 'free moves' by members of our speech community—they are available to just about anyone any time to use as premises, to assert unchallenged.
- Adler, Jonathan (2002). Belief’s Own Ethics. Cambridge: MIT Press. pp. 164–167. ISBN 0262011921.
- Steven D. Hales (2005). "Thinking Tools: You Can Prove a Negative" (PDF). Bloomsburg University.
- T. Edward Dame (2009). Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments. Cengage Learning. p. 17. ISBN 9780495095064.
- "The Atheist Experience". Episode 808. 7 April 2013. channelAustin 16. Missing or empty
- Matt Dillahunty (2013). Does God Exist? (Debate). Texas State University.
- "Metacognitive Model of Ambivalence: The Role of Multiple Beliefs and Metacognitions in Creating Attitude Ambivalence".
- "Reductionism, emergence, and burden of proof — part I".
- "Reductionism, emergence, and burden of proof — part II".