Actually the term “burden of proof” is a little strong since it implies the need to prove beyond any doubt so in practice it is really the burden of evidence. The side that has the burden of proof is obligated to provide evidence to back up their view point.
Determining the burden of proof is not always easy to do because it varies in different circumstances and changes in the course of the discussion.
Finding the Burden of ProofThe burden of proof usually goes to the party making the claim. A criminal trial in the
Burden of Proof FallacyThe Burden of Proof Fallacy is the act of wrongfully trying to switch the burden of proof to your opponent. As an example proponents of abiogenesis need to prove that it is possible because it is already know that intelligence can produce complex organized systems. On the other hand there is no real evidence for abiogenesis. Al its proponents provides is unproven stories about how it could have happened.
Legitimate Switching of the Burden of ProofThe Burden of Proof can legitimately switch sides if new arguments have been made or evidence presented. If the opposition wishes to dispute the new evidence or argument, they have the burden of proof in doing so. Hence the burden of proof has switched.
The biggest problems in a discussion is agreeing on who has the burden of proof. It can consume much time and render a debate useless. Another problem is that since each side sees the issue differently it may be hard to agree on burden of proof.