Occam's Razor

Philosophical Position

Occam's Razor is a philosophical position which can be expressed in several ways, including the following:

• The simplest explanation is probably the correct one.
• When seeking to explain a phenomenon, choose the hypothesis which requires the fewest postulates.
• Demonstration by fewer postulates or hypotheses (in short from fewer premises) is ceteris paribus superior; for, given that all of these are equally well known, where they are fewer, knowledge will be more speedily acquired, and that is a desideratum. (Aristotle, from Analytica Posteriora).
• We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore, to the same natural effects we must, so far as possible, assign the same causes (attributed to Isaac Newton).
• Keep It Simple, Stupid (used as a design principle).

It has profound philosophical implications, and considerable scope for misuse.

Also known as

More accurately, the name should strictly be given as Ockham's Razor, but this usage is rare.

Occam's Razor is also known in Latin as the lex parsimoniae (which translates as the law of economy or law of succinctness).

Source of Name

This entry was named for William of Ockham.

Historical Note

In the words of William of Ockham himself, Occam's Razor was expressed as:

entia non sunt multiplicanda praeter necessitatem (entities must not be multiplied beyond necessity)

or:

pluralitas non est ponenda sine necessitate (plurality should not be posited without necessity).

He was not the first to voice this philosophy. For example, Aristotle had expressed a similar philosophical position.

Sources

• 1966: Isaac Asimov: Understanding Physics ... (previous) ... (next): $\text {I}$: Motion, Sound and Heat: Chapter $1$: The Search for Knowledge: The Greek View of Motion