Oc­cam’s Razor

TagLast edit: 8 Oct 2020 1:15 UTC by Ruby

Occam’s razor is a principle commonly stated as “Entities must not be multiplied beyond necessity”. When several theories are able to explain the same observations, Occam’s razor suggests the simpler one is preferable. It must be noted that Occam’s razor is a requirement for the simplicity of theories, not for the size of the systems described by those theories. For example, the immensity of the Universe isn’t at odds with the principle of Occam’s razor.

Occam’s razor is necessitated by the conjunction rule of probability theory: the conjunction A and B is necessarily less (or equally, in the case of logical equivalence) probable than the A alone; every detail you tack onto your story drives the probability down.

Occam’s razor has been formalized as Minimum Description Length or Minimum Message Length, in which the total size of the theory is the length of the message required to describe the theory, plus the length of the message required to describe the evidence using the theory. Solomonoff induction is the ultimate case of minimum message length in which the code for messages can describe all computable hypotheses. This has jokingly been referred to as “Solomonoff’s lightsaber”.

Notable Posts

See Also

External Links

Math­e­mat­ics as a lossy com­pres­sion al­gorithm gone wild

shminux6 Jun 2014 23:53 UTC
52 points
80 comments5 min readLW link

A Proof of Oc­cam’s Razor

Unknowns10 Aug 2010 14:20 UTC
2 points
139 comments3 min readLW link

[Question] In­stru­men­tal Oc­cam?

abramdemski31 Jan 2020 19:27 UTC
30 points
15 comments1 min readLW link

Tak­ing Oc­cam Seriously

steven046129 May 2009 17:31 UTC
32 points
51 comments1 min readLW link

In­duc­tion; or, the rules and eti­quette of refer­ence class tennis

paulfchristiano3 Mar 2013 23:27 UTC
11 points
8 comments9 min readLW link

Msg Len

Zack_M_Davis12 Oct 2020 3:35 UTC
54 points
4 comments1 min readLW link

Mes­sage Length

Zack_M_Davis20 Oct 2020 5:52 UTC
122 points
22 comments12 min readLW link

Very Short In­tro­duc­tion to Bayesian Model Com­par­i­son

johnswentworth16 Jul 2019 19:48 UTC
28 points
5 comments1 min readLW link

Dis­solv­ing the Prob­lem of Induction

Liron27 Dec 2020 17:58 UTC
34 points
32 comments7 min readLW link

A Semitech­ni­cal In­tro­duc­tory Dialogue on Solomonoff Induction

Eliezer Yudkowsky4 Mar 2021 17:27 UTC
92 points
16 comments54 min readLW link

Oc­cam’s Razor

Eliezer Yudkowsky26 Sep 2007 6:36 UTC
77 points
56 comments5 min readLW link

The Strong Oc­cam’s Razor

cousin_it11 Nov 2010 17:28 UTC
17 points
74 comments3 min readLW link

Oc­cam’s Ra­zor May Be Suffi­cient to In­fer the Prefer­ences of Ir­ra­tional Agents: A re­ply to Arm­strong & Mindermann

Daniel Kokotajlo7 Oct 2019 19:52 UTC
46 points
39 comments7 min readLW link

Against Oc­cam’s Razor

zulupineapple5 Apr 2018 17:59 UTC
3 points
20 comments1 min readLW link

If Many-Wor­lds Had Come First

Eliezer Yudkowsky10 May 2008 7:43 UTC
73 points
181 comments9 min readLW link

Where Re­cur­sive Jus­tifi­ca­tion Hits Bottom

Eliezer Yudkowsky8 Jul 2008 10:16 UTC
84 points
76 comments10 min readLW link

Belief in the Im­plied Invisible

Eliezer Yudkowsky8 Apr 2008 7:40 UTC
47 points
34 comments6 min readLW link

A Priori

Eliezer Yudkowsky8 Oct 2007 21:02 UTC
59 points
134 comments4 min readLW link

De­co­her­ence is Simple

Eliezer Yudkowsky6 May 2008 7:44 UTC
50 points
61 comments11 min readLW link

Kevin T. Kelly’s Ock­ham Effi­ciency Theorem

Johnicholas16 Aug 2010 4:46 UTC
43 points
82 comments5 min readLW link

The prior of a hy­poth­e­sis does not de­pend on its complexity

cousin_it26 Aug 2010 13:20 UTC
34 points
69 comments1 min readLW link

[Question] Why would code/​English or low-ab­strac­tion/​high-ab­strac­tion sim­plic­ity or brevity cor­re­spond?

curi4 Sep 2020 19:46 UTC
2 points
15 comments1 min readLW link

Psy­chic Powers

Eliezer Yudkowsky12 Sep 2008 19:28 UTC
30 points
89 comments3 min readLW link

Notes on Simplicity

David_Gross2 Dec 2020 23:14 UTC
8 points
0 comments7 min readLW link

Prob­a­bil­ity the­ory im­plies Oc­cam’s razor

Maxwell Peterson18 Dec 2020 7:48 UTC
8 points
4 comments6 min readLW link

State, Art, Identity

musq25 Jan 2021 20:22 UTC
1 point
0 comments2 min readLW link
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