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Theory of Knowledge

Are Spinozistic Ideas Cartesian Judgements?

Timo Kajamies
University of Turku

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ABSTRACT: Some commentators maintain that Spinozistic active ideas are judgements. I shall call this view the common interpretation, since it is popular to interpret Spinoza as reacting against Descartes’ theory of ideas. According to this reading, Spinozistic ideas are considered not as Cartesian ideas but as Cartesian judgements. One clear difference between Descartes and Spinoza is that Spinoza holds that ideas are active, while Descartes does not. According to the common interpretation, Spinoza and Descartes use the concept of activity in the same way. Since Descartes holds that judgements are active, it is maintained that Spinozistic active ideas are like Cartesian judgements. I find this an overly superficial interpretation of Spinoza. I argue that, for Spinoza, activity denotes more than mere Cartesian activity. Whereas Spinoza wants to say that active ideas incorporate the property of truth or certainty, Descartes does not consider judgements in that way. In this way, Spinozistic active ideas can be called truth-expressing.

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Some commentators of Spinoza maintain that Spinozistic ideas are judgements. I shall call this view the common interpretation, since it is popular to interpret Spinoza as reacting against Descartes’s theory of ideas and accordingly consider Spinozistic ideas not as Cartesian ideas, but as Cartesian judgements.

The clearest difference between Descartes and Spinoza here is that whereas Descartes thought that ideas are passive, Spinoza thought the opposite. The concept of activity plays accordingly an important role in interpreting Spinoza’s theory of ideas. According to the common interpretation Spinoza and Descartes use the concept of activity in the same way. And since Descartes thought that judgements are active, it is maintained that the Spinozistic, active ideas are like Cartesian judgements.

I find that the considerations according to which the activity of Spinozistic ideas is seen in the light of Descartes’s distinction between action and passion are based on too superficial an interpretation of Spinoza. I argue that what Spinoza means by saying that ideas are active does not merely mean that they are active in a Cartesian sense. He has in mind something additional to the mere Cartesian activity. Whereas Spinoza wants to say that active ideas incorporate the property of truth or certainty, Descartes does not think in that way about judgements. Thus, the Spinozistic ideas can be called truth-expressing.


René Descartes brought the concept of idea into a central place in epistemology. Another famous rationalist—Benedictus de Spinoza—made use of the same term "idea", but had an entirely different view concerning the nature of ideas. Whereas Descartes thought that ideas are passive, Spinoza had the opposite view according to which ideas are active.

In this paper I shall examine what Spinoza means by the activity of ideas. According to some commentators Spinozistic ideas should be seen as Cartesian judgements. I call this view the common interpretation and I shall argue that it does not capture the whole of Spinoza’s theory of active ideas. The activity of Spinozistic ideas is something more than merely the kind of activity found in Cartesian judgements.

In the first part I will sketch Descartes’ conception of ideas as passive. In the second and third part I move on the outline Spinoza’s position and point out that there are passages which motivate the common interpretation. In the fourth part I will proceed to argue that the activity of Spinozistic ideas is not merely that of Cartesian judgements. By linking Spinoza’s notion of activity to truth and adequacy it can be seen that the activity at hand is intimately connected with certainty. In the fifth and sixth part I complete the argument. The conclusion will be that whereas Descartes did not require certainty of ideas, Spinoza did. To Spinoza having an idea amounts to being certain. Thus, the activity in Spinoza’s ideas is more than the activity in Descartes’s judgements.

1. Descartes’s Conception of Ideas and Judgement in Outline

Descartes thought that the human mind is capable of two kinds of performances—actions and passions. (1) There are two faculties in the mind performing the operations. One is called the intellect and the other is called will. (2) Intellect is capable of passive operations only; it is totally passive. Conversely, will is active.

The two faculties and their two separate domains of performances are Descartes’ link to ideas and judgements; he calls the passive operations of the intellect by the term "idea" and leav3s the term "volition" to stand for the active operations of the will. A special class of volitions is the class of judgements.

We now have Descartes’s theory of ideas and judgements in a nutshell. Ideas belong to the passive side of the mind—the intellect—whereas judgements inhabit the active side—the will. Moreover, Descartes thinks that there is a one-way dependence relation between ideas and judgements: it needs ideas to be judgements, (3) but not vice versa. Judgements are made towards ideas; they are acts of assenting and dissenting made towards ideas.

But how can assent to an idea? An act of judging seems not to be directed towards an idea, but towards a proposition. In fact, Descartes thinks that ideas can be expressed in a propositional form, and thus he can very well maintain that the object of judgement is a proposition—an idea in a propositional form.

Let me still give an example in the light of which it could be easier to appreciate Descartes’s theory. Suppose that I have an idea of my wife, say, the idea that she has a brown hair. Let us label this idea by ‘My wife has a brown hair’. The idea belongs to the domain of my intellect and is passive. Now, when I make a judgement, I make it towards this idea. My judgement is giving a "yes" or a "no". (4) The judgements I can make amount therefore to something like the following ones:

(a) "’My wife has a brown hair’; yes!"

(b) "’My wife has a brown hair’; no!"

Both (a) and (b) are judgements and contain an idea towards which the judgement is made. Both are active and contain a passive part.

2. Spinoza and Ideas

Spinoza has a radically different view of ideas than Descartes. He denies that ideas are passive and maintains instead that they are active. This is what Spinoza says in 2d3 and its explication:

By an idea I understand a conception of the Mind which the Mind forms because it is a thinking thing.

Explication: I say ‘conception’ rather than perception because the term perception seems to indicate that the Mind is passive to its object, whereas conception seems to express an activity of the Mind.

Spinozistic ideas are conceptions, not perceptions, because conceptions are active and perceptions passive. Now, Descartes called ideas passive and one of his terms standing for ideas was "perception". It seems therefore very straightforward to regard Spinoza as reacting against Descartes. Under this interpretation Spinoza wants to say that he does not accept the Cartesian view that ideas are passive.

What are Spinozistic ideas, then, if not Cartesian ideas? The common interpretation is that they are like Cartesian judgements. After all, Spinoza says that ideas are active, and Descartes, whom he opposes, thought that judgements are active. According to the common interpretation the Spinozistic ideas are inherently judgemental.

Eminent scholars have thought that Spinoza’s point in calling ideas active is that he sees ideas as Cartesian judgements. Margaret Wilson (5) puts the point by saying that according to Spinoza "judgement is not something added to distinct mental entities; rather thought, or the mental, is inherently and essentially judgmental…" G.H.R. Parkinson (6) says that when Spinoza discusses the activity in ideas "he seems to have Descartes in mind" and the "the point at issue concerns the nature of judgement". What Parkinson ends up with is that "for Spinoza an idea is a judgement".

3. Evidence for the Common Interpretation

One can easily find passages which seem to support the common interpretation. Contrary to Descartes, Spinoza thinks that there are no such things as faculties of intellect and will, only particular acts of mind. (7) Furthermore, the supposed intellect and will are identical, (8) so according to Spinoza the Cartesian ideas and judgements would be identical. But would they be like ideas or like judgements? In 2p49 Spinoza says that "there is in the mind no volition, that is, affirmation and negation, except that which an idea, in so far as it is an idea, involves". This seems not to leave room for saying that Spinoza wants to accept Descartes’s ideas. No, he wants to say that ideas involve an affirmation or negation, so the ideas he accepts seem to be like Cartesian judgements.

In 2p49s Spinoza says that ideas cannot be like "dumb pictures on a tablet", but that they involve affirmation or denial. Furthermore, Spinoza thinks that an idea which involves affirmation or denial is not to be confused with words, so Spinozistic ideas involve taking a stand towards something. It is very tempting to read the activity in ideas as meaning the act of taking a stand—making a judgement.

I shall now proceed towards my suggestion that the activity Spinoza talks about is not merely the activity found in Cartesian judgement, but in fact something much stronger.

4. Activity, Truth, and Adequacy in Spinozistic Ideas

We must now ask what Spinoza means by activity in ideas. In 2p43s Spinoza says that having a true idea amounts to knowing a thing perfectly. He further thinks that this fact can be doubted only by those who think that an idea is like a dumb picture and not an act of understanding. So Spinoza wants to contrast acts of understanding with pictures. Ideas are acts of understanding, not pictures.

In fact, in Spinoza’s philosophy the terms "act" and "understanding" are remarkably close to each other in meaning. The acts of understanding are understandings in the sense that when s performs an act of understanding, she understands. To see this, note first that an act of understanding is, of course, an act. According to Spinoza the mind "is in some instances active and in other instances passive". (9) Acts of understanding indicate, being acts, that the mind is active while performing them. The contact between an act and understanding shows itself now, when we see that Spinoza says in 4p23p that "we are active only in so far as we understand". Therefore, I conclude that according to Spinoza, to perform an act of understanding is to understand. Spinoza would accept the following principle:

(AU): s performs an act of understanding towards x, iff s understands x while performing the act.

Since we already know that according to Spinoza ideas are acts of understanding, we can infer that he would also accept the following principle:

(IU): s has an active idea of x, iff s understands x (while having the idea). (10)

Spinoza comments on understanding in 4p26. He says that "Whatever we endeavor according to reason is nothing else but to understand; and the mind, in so far as is exercises reason, judges nothing else to be to its advantage except what conduces to understanding". I take this to imply that it takes reason to understand something. Actions, and therefore also ideas, can accordingly be linked to reason, and we get the following principle:

(IR): s has an active idea of x, iff, s acts according to reason.

What kind of guide is reason in one’s actions? In 2p40s Spinoza says that he means by reason something he calls "knowledge of the second kind". And in 2p41 and its proof he says that knowledge of the second kind—i.e. reason—is necessarily true and belongs to those ideas which are adequate.

We can now reformulate the Spinozistic principle of ideas again. We get the following two principles:

(IT): if s has an idea of x, s acts according to truth. (11)

(IA): if s has an idea of x, s acts according to adequacy.

Truth and adequacy are in Spinoza’s philosophy addectively equivalent. (12) A true idea means the same thing as an adequate idea. Therefore, (IT) and (IA) mean the same thing. Concerning my argument, however, the most important relation is not that between truth and adequacy, but that between truth and certainty, or adequacy and certainty.

5. Truth, Adequacy, and Certainty

The most important passage in the Ethics concerning certainty and its converse—doubt—is 2p43 and its cognates. The proposition reads:

He who has a true idea knows at the same time that he has a true idea, and cannot doubt its truth.

Spinoza thinks that a true idea is such that it expresses its truth value, as it were. In the proof of 2p43 Spinoza considers an adequate human idea. After having considered what is meant by an adequate human idea he ends up with a view that he who has an adequate idea "is bound at the same time to be certain". Truth and adequacy are accordingly self-revealing: nothing else is required for being certain of something than to have a true idea of it.

In 2p43s Spinoza explicates his position by saying that "nobody who has a true idea is unaware that a true idea involves absolute certainty" and that "to have a true idea means only to know a thing perfectly, that is, to the utmost degree". Spinoza’s position is, then, that truth amounts to certainty. Now that we know that Spinoza equates truth, adequacy and certainty, we can formulate a new principle:

(IC): if s has an idea of x, s acts according to certainty.

What does it mean to say that one acts according to certainty? It appears to mean that one takes certainty as his guide or guiding rule when one acts. And when one does this, one most certainly is certain. Listening only to certainty cannot make it happen that one loses his assured state of mind. When I act according to certainty, I refuse to accept anything that is beyond certainty. Therefore, to act according to certainty with respect to something is being certain of it.

We now have a very interesting principle:

(IC’): if s has an idea of x, s is certain of x.

Furthermore, if (IC’) is correct, we have gained an important insight concerning Spinoza’s notion of activity in ideas.

6. The Spinozistic Ideas and the Common Interpretation

My question was what does the activity in Spinoza’s ideas mean. After having observed that Spinoza wants to pack the notion of activity into ideas, I proceeded to examine the notion of activity. The outcome was that the activity amounts to certainty. What Spinoza means by his claim that ideas should be construed as active is that they are inherently certain.

How does the result I propose relate to the common interpretation? Since the common interpretation was that the activity in Spinozistic ideas is the same as the activity in Cartesian judgements, the question is how does the activity in judgements differ from the activity relating to certainty.

Let us think about one of the judgements I mentioned earlier. The judgement was "’My wife has a brown hair’; no!" According to the common interpretation the activity Spinoza chases after is like the act of will which merely adds a "no" to the idea. The common interpretation prescribes, then, that the Cartesian idea plus a "no" deserves to be called a Spinozistic active idea.

Suppose now that I make the above judgement. According to the common interpretation this would suffice in that I have a Spinozistic active idea of my wife. But let us now think of the situation in the light of the interpretation I have defended above. The fact is that my wife has a brown hair, and at least the Spinozistic God knows this. The judgement at hand is accordingly false and cannot be certain. This means that this Cartesian judgement cannot be a Spinozistic idea, since is cannot be accompanied by certainty.

I conclude, therefore, that the activity in Spinozistic idea should not be considered straightforwardly against Descartes’s theory, but instead it should be considered as involving a complete assurance or certainty. This would mean that when Spinoza attacks the view that ideas are like "dumb pictures on a tablet" and argues for their activity, he does not want to change the reference of the term "idea" from Cartesian ideas to Cartesian judgements. What he wants to do is to attack a theory which construes ideas as mere opinions of imaginations. He wants to argue for a theory which packs certainty into the things that deserve to be called active ideas.

7. Conclusion

In this paper I have argued that the common interpretation of the activity in Spinozistic ideas is based on a misunderstanding. The interpretation overlooks an important aspect in Spinoza’s philosophy, namely the fact that he equates truth with certainty and sees ideas as acts of understanding involving truth. I think that the confusion arises out of bringing Descartes’s notion of mental activity into play in interpreting Spinoza. Spinozistic ideas can be like Descartes’s judgements, but they have the property of certainty as an additional element. Even thought Spinoza’s theory of ideas is drastically different from Descartes’s theory and in many respects is a reaction against Descartes’s theory, Spinoza’s theory of ideas and especially the notion of activity is well worth examining in its own right, not always in the Cartesian light.

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(1) CSM I, 335; AT XI, 342.

(2) CSM I, 204; AT VIIIA, 17.

(3) CSM I, 204; AT VIIIA, 18.

(4) I simplify the picture a bit, since "I do not know" seems to be a possible judgement also.

(5) See her illuminating "Spinoza’s Theory of Knowledge." In Garrett, Don (ed.) The Cambridge Companion to Spinoza (CUP, 1996), 89-141.

(6) Spinoza’s Theory of Knowledge (OUP, 1964), 93-94.

(7) 2p48s.

(8) 2p49c.

(9) 3p1.

(10) The phraze in brackets may yield circularity. I omit that pheaze in each of the following principles, but it must be borne in mind that the same mental act is referred to in both sider of the equivalence.

(11) Since Spinoza thinks that also the knowledge of the third kind is true, I formulate the principles from now on in the form of one-way implication.

(12) Wilson, "Spinoza’s Theory of Knowledge," 109.

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