Evidence and a cumulative case for God › Two strengths of inductive argument

A valid deductive argument makes its conclusion follow necessarily from its premises. If the premises are true, its conclusion cannot be false. Swinburne's cumulative case instead concerns induction: premises can support a conclusion without guaranteeing it. The evidence can be genuine evidence even if the conclusion ultimately turns out to be mistaken.

He distinguishes two kinds of successful inductive argument. A C-inductive argument increases the probability of its conclusion. A P-inductive argument makes its conclusion more probable than not. The first expresses confirmation; the second expresses a stronger overall judgment. These definitions appear explicitly in his own discussion of arguments for God's existence.

A consideration can meet the first standard while falling short of the second. An explanation that begins with a very low probability might receive support without becoming likely overall. Thus saying that an observation favors theism does not yet establish that theism is probable. The cumulative project needs to address the starting assessment and the combined force of the evidence.

The distinction works in the other direction as well. A piece of counterevidence can lower the probability of a hypothesis without making it improbable overall. Reasoning about a cumulative case therefore requires tracking both the direction and the strength of an update. Counting favorable and unfavorable considerations is insufficient.

Swinburne's proposal is that several arguments can contribute to an overall probable conclusion. This does not mean that each traditional argument independently proves God or that every item discussed in the book supports theism. Questions about suffering, rival explanations, and the force of reported experiences belong inside the evaluation.