Ignorantia non est argumentum
"Ignorantia non est argumentum." Translation: "Ignorance is no argument." Source: Ethica ordine geometrico demonstrata et in quinque parses distincta, Part 1, Addendum; Amsterdam, 1677.
I have not found this particular quote in any paragraph of part 1 in Ethics. I have seen it on the internet more often (even on the BBC Web site), but it seems to me that it is not an actual quote, but rather an idea of Spinoza put in a quick "tag-line"
The closest I could find was:
"We must not omit to notice that the followers of this doctrine, anxious to display their talent in assigning final causes, have imported a new method of argument in proof of their theory--namely, a reduction, not to the impossible, but to ignorance; thus showing that they have no other method of exhibiting their doctrine."
Source: Ethics by Benedict de Spinoza (1677) Translated from the Latin by R.H.M. Elwes (1883) MTSU Philosophy WebWorks Hypertext Edition
Mcmvanbree 20:08, 20 December 2005 (UTC)
The actual quote "ignorantia non est argumentum" is attributed to Friedrich Engels in Anti-Duhring (Herrn Eugen Dühring's Umwälzung der Wissenschaft ("Anti-Dühring"), Kap. IX, Moral und Recht. Freiheit und Notwendigkeit): "Worauf wir nur mit Spinoza antworten können: Ignorantia non est argumentum, die Unwissenheit ist kein Beweisgrund." 18.104.22.168 08:36, 21 October 2013 (UTC)
This is the best Wikiquote page I've come across. Whoever has done it did an absolutely sterling job. Thanks very much!
Changes made on 2013-08-28
Added "all things excellent..." from the Ethics. Found the correct source and wording for "Peace is not mere absence of war..." (it is in the Political Treatise, not the Theological-Political Treatise). Grommel (talk) 20:41, 28 August 2013 (UTC)