III.D15: Desperation Defined

Desperatio est tristitia orta ex idea rei futuræ vel præteritæ de qua dubitandi causa sublata est.

Desperation is a sadness born of the idea of a future or past matter which has been raised as a cause for concern.

EXPLICATIO: Oritur itaque ex spe securitas et ex metu desperatio quando de rei eventu dubitandi causa tollitur, quod fit quia homo rem præteritam vel futuram adesse imaginatur et ut præsentem contemplatur vel quia alia imaginatur quæ existentiam earum rerum secludunt quæ ipsi dubium injiciebant. Nam tametsi de rerum singularium eventu (per corollarium propositionis 31 partis II) nunquam possumus esse certi, fieri tamen potest ut de earum eventu non dubitemus. Aliud enim esse ostendimus (vide scholium propositionis 49 partis II) de re non dubitare, aliud rei certitudinem habere atque adeo fieri potest ut ex imagine rei præteritæ aut futuræ eodem lætitiæ vel tristitiæ affectu afficiamur ac ex rei præsentis imagine, ut in propositione 18 hujus demonstravimus, quam cum ejusdem scholiis vide. 

Thus security arises from hope desperation from fear when the cause for doubting the eventual outcome is raised, because it happens since a person imagines a past or future thing as present and as one contemplates the present thing or other things one imagines which exclude the existence of these things which throw themselves into doubt. For even if concerning the outcome of singular things (by IIP31C) we are unable to be certain, nonetheless it can happen that we do not doubt the outcome of them. For we have shown that it is one thing (see IIP49S) to not doubt something, something else to have certainty about a matter and to such an extent it is able to happen that from the image of a past or future thing we are affected by an affect of joy or sadness and from the image of the thing present, as we have shown in IIIP18, then see with scholia of the same. 

The explanation here is important for an insight into Spinoza's view on thinking. We might commonly hold that not doubting something is the same as being certain of something, but still most of us actually hold that not doubting someone is the same as "believing" someone. Certainty has a much higher standard and most of us have faced that dreaded question, "Are you certain?" only to find some hesitation. Spinoza is setting out a tool for managing the reactivity of hopes and fears by allowing these affects to be muted by a simple question "Are you certain?"