Are "fault" and "default" etymologically related?

Question

Fault and default sound rather similar to me as a German, but are they really related?

I am interested in default as used in default value for some configurable setting in computer programs.

Answer 1

Fault

late 13c., faute,
"deficiency," from O.Fr. faute (12c.)
"opening, gap; failure, flaw, blemish; lack, deficiency," from V.L. *fallita "a shortcoming, falling," noun use of fem. pp., from L. falsus
"deceptive, feigned, spurious," pp. of fallere "deceive, disappoint" (see false).

The -l- was restored 16c., probably in imitation of Latin, but was not pronounced till 18c.

Sense of "physical defect" is from early 14c.;
that of "moral culpability" is first recorded late 14c.
Geological sense is from 1796.
The use in tennis (c.1600) is closer to the etymological sense.

Default

early 13c., "offense, crime, sin," later (late 13c.) "failure, failure to act," from O.Fr. defaute (12c.)
"fault, defect, failure, culpability, lack, privation," from V.L. *defallita "a deficiency or failure," pp. of *defallere, from L. de- "away" (see de-) + fallere
"to deceive, to cheat; to put wrong, to lead astray, cause to be mistaken; to escape notice of, be concealed from" (see fail).
The financial sense is first recorded 1858; the computing sense is from 1966.

Wikipedia says

The Oxford English Dictionary dates this usage to the mid-1960s, as a variant of the older meaning of "failure in performance".

[bold is mine]

Answer 2

Yes, they are related.

According to Etymonline, fault traces its ancestry back through the Old French faute to the Latin fallere, "to deceive". Similarly default traces back through the Old French defaute to the Latin defallere, which is just de- ("away from" or "out of") + fallere.

"Default" in the computing sense straightforwardly derives as the value chosen "by default", or "in default of" an explicit value. In both of those phrases "default" is used to mean a lack or omission, part of its ordinary definition.

Answer 3

The logic behind the use of "default value" in software is a bit twisted. It is based on the programmer looking at the user's actions entirely from computer's point of view. For example, by pressing Ctrl-P to print a file, you point out the file and the action, but leave out plenty of other information the computer needs to carry out your request to print a file. To fill in the missing data, the computer uses “default values” as a way to "de-fault" your omission, so to say.

In other words, in a programmers' world-view, the user is always at fault.