The ampliative argument: reasoning in uncertainty

Real-World Logic

Formal logic, with its perfect syllogisms ("if A, then B"), is rarely directly applied to the complexity of the real world.

Most of our everyday decisions and reasoning are based on incomplete information and a degree of uncertainty.

This type of reasoning is known as ampliative argument or inference.

Plausible Conclusions, Not Warranted

An ampliative argument is one whose conclusion goes beyond what is strictly contained in the premises.

The conclusion is plausible or probable, but not warranted.

For example, the premise "this food is healthy" leads us to the plausible conclusion that "if I eat it, I will feel better."

However, this conclusion is not warranted.

There are countless factors not in the premise that could affect the outcome: how the food was prepared, my current health, what other things I've eaten, etc.

Living with Inference

Virtually all of our knowledge about the world is inferential.

We infer that the sun will rise tomorrow because it has every day so far.

We infer that the chair will support our weight because it has in the past.

We don't have absolute certainty, but we operate with a high degree of probability based on experience.

Evaluating Inductive Strength

Because we live in a world of inference, critical thinking is not about seeking absolute certainties, but about evaluating the inductive strength