Philosophic burden of proof
In epistemology, the burden of proof or onus probandi is the obligation on a party in an epistemic dispute to provide sufficient warrant for their position.
Holder of the burden
When two parties are in a discussion and one affirms a claim that the other disputes, the one who affirms 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, but is not valid reasoning.
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.
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 affirmed claim that conjects the non-existence or exclusion of something; when disputed, proof of impossibility or evidence of absence are typical methods to fulfil the burden of proof. Such a claim may exist as a counter point to a previous claim. 
Matt Dillahunty gives the example of a large jar full of gumballs to illustrate the burden of proof. It is a fact of reality that the number of gumballs in the jar is either even or odd, but the degree of personal acceptance or rejection of claims about that characteristic is more nuanced depending upon the evidence available. We can choose to consider two claims about the situation, given as:
- The number of gumballs is even.
- The number of gumballs is odd.
These two claims can be considered independently. Before we have any information about the number of gumballs, we have no means of distinguishing either of the two claims. When we have no evidence favoring either proposition, we may suspend judgment. If there is a claim proposed and that claim is disputed, the burden of proof falls onto the proponent of the claim. 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. [unreliable source?][unreliable source?]
- 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.
- "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. 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.
- 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".