# Three Modes of Inference

**Induction**:

– Specific –> General: A…B… –> Rule of A and then B

– Fact –> Rule

– General: conjecture, guess, estimation, generalization, rule

**Deduction**:

– General –> Specific: Rule of A and then B + A –> B

– Rule –> Fact

**Abduction (“retroduction”)**:

– General –> Specific: Rule of A and then B + B –> A

– Rule –> Fact

TOTAL SEQUENCE: (Induction = 1) (Abduction = 2) (Deduction = 3, 4, 5)

1. Observe (a pattern) –>

2. Make guesses about how things generally work –>

3. Observe (later / similar thing) –>

4. New observation + Guesses –>

5. Assumed (unobserved / deduced) value

Aristotle vs. Sherlock?

Sherlock vs. House?

Formal Logic (deduction) vs. Informal Logic (induction)

Two Kinds of Thinking

Deduction & Induction: a co-dependent relationship

Circle of Logic

Valuing Deductions and Inductions & Cogency & etc.

From Reality to Truth

**Abduction:** http://individual.utoronto.ca/jmwilson/Biggs-Wilson-The-APriority-of-Abduction.pdf**
Comparison of Induction & Deduction:** http://www.personal.kent.edu/~rmuhamma/Algorithms/MyAlgorithms/DeductInduct.htm

**Math Lessons on Induction & Deduction:** https://www.khanacademy.org/math/algebra-home/alg-series-and-induction/alg-deductive-and-inductive-reasoning/v/deductive-reasoning-1