Inference

Inference is deduction. There is no other form of inference.

Inference draws a conclusion that follows necessarily from premises. If the premises are true, the conclusion must be true.

Properties

Inference:

• is deductive: the conclusion follows necessarily from the premises
• consists of making explicit what is already contained in the premises

Inference does NOT:

• generate new explanatory content
• include conjecture, abduction, or computation

Distinctions

Conjecture is a creative act: the proposal of an explanation. It is not derived from observations. It is invented.

Computation is a mathematical operation. Extrapolation, curve fitting, and statistical projection produce outputs from inputs. They are calculation, not reasoning.

Abduction consists of conjecture and criticism. The conjecture is creative. The criticism uses deduction to derive testable consequences. The inferential work within abduction is deductive. Abduction itself is not a form of inference. It is a process that contains inference.

Philosophy has traditionally counted three forms of inference: deduction, induction, and abduction. Induction is a misdescription. Abduction contains deduction but is not itself inference. There is one form of inference.

Example

If the battery is dead, the car will not start. The battery is dead. Therefore, the car will not start.

The conclusion adds nothing not already present in the premises. It makes the implicit explicit.

Implications

1. Conjecture is fundamental. The growth of knowledge depends on creative guesses not derived from anything. Inference cannot produce new explanatory content.

2. Criticism is deductive. When we test a conjecture, we deduce its consequences and compare them against observation.

3. The terminology misleads. Calling conjecture and computation "inference" obscures the distinct roles of creativity, logic, and calculation in the growth of knowledge.

2026-02-25 Aaron Brinton