In the Fourth Meditation it is proved that everything that we clearly and distinctly perceive is true, and I also explain what the nature of falsity consists in. These results need to be known both in order to confirm what has gone before and also to make intelligible what is to come later. Synopsis p11
After establishing the existence of God in the Third Meditation, Descartes is now able to pursue knowledge that goes beyond subjective self-awareness. ‘I think I can see a way forward to the knowledge of other things’ (p37), as he cautiously puts it. The crucial step here is the claim that God would not deceive him in his clear and distinct perceptions. This allows a systematic answer to the systematic doubt of the First Meditation, and guarantees that objective and certain knowledge is available after all.
Descartes’ argument that God could not deceive him is curiously brief. Since the will to deceive is an imperfection, and God is a perfect being, ‘it is impossible that God should ever deceive me’ (p37). Even if we accept this rather shaky reasoning, there is an immediate problem: if God is perfect, then why has Descartes been deceived so often before? If God does not deceive, what is the source of error?
I realize that I am, as it were, something intermediate between God and nothingness, or between supreme being and non-being. M4 p38
Descartes’ account of error begins with a description of the act of judgement, which is where he understands that mistakes are made. The faculty of judgement involves both the intellect and the will: the intellect conceives an idea (for example, that the sun is huge and far away) and presents it to the will. The will then assents to this idea, or rejects it. Error occurs when the will assents to an idea that is materially false.
The human intellect, like the faculties of memory and imagination, is limited. An idea in the understanding, even a fictitious one like Hamlet or a chimera, cannot be strictly untrue, in so far as it is merely an idea. But since it is finite, the intellect lacks something: many ideas, many details are missing from human understanding. This allows for materially false ideas, or confused or partial conceptions, to which the will may wrongly assent.
The will, on the other hand, is infinite:
This is because the will simply consists in our ability to do or not do something (that is, to affirm or deny, to pursue or avoid); or rather, it consists simply in the fact that when the intellect puts something forward, we are moved to affirm or deny or to pursue or avoid it in such a way that we do not feel ourselves to be determined by any external force. M4 p40
An infinite will is completely free to affirm or deny any or all contents of the intellect. Error arises because we do not restrict our will only to what we understand clearly and distinctly: we accept and affirm ideas without due consideration or full comprehension. As Descartes puts it, ‘the scope of the will is wider than that of the intellect’ (p40), which accounts for our tendency towards wishful thinking and poor judgement. Properly deployed, our intellect cannot make mistakes, since our clear and distinct perceptions are underwritten by God.
What this means in practice is that we should suspend judgement and withhold our assent in the absence of clear and distinct ideas:
... if, whenever I have to make a judgement, I restrain my will so that it extends to what the intellect clearly and distinctly reveals, and no further, then it is quite impossible for me to go wrong. M4 p43
Before Descartes’ investigation we were lazy thinkers, easily misled by the senses and liable to jump to conclusions without due consideration. Now we see that we must restrict our belief, at first anyway, to only those matters that can be understood clearly and distinctly and suspend our judgement regarding everything else. That, of course, is exactly what Descartes does at this point with regard to the existence of the physical world. As we have seen, the type of belief that can be conceived with due clarity and distinctness tends to be mathematical or scientific (‘scientific’ in the sense of logical deduction concerning the true nature of reality, which will translate eventually into the laws of physics). Therefore, Descartes is saying, to avoid error we should develop a rigorous scientific account of the world, the truth of which will be guaranteed by God’s goodness.
This account of belief as assent to ideas was addressed briefly in the First Meditation, where scepticism was understood as withholding assent from beliefs that were open to doubt. It is worth asking whether this psychological model is convincing.
An obvious objection is that we do not always choose our beliefs freely. There are plenty of things that we cannot believe, or cannot help believing. Believing in the face of evidence, or its absence, is not usually possible: try convincing yourself that George Washington was never President, or that the exact current population of the world is an odd number. Similarly, it is hard not to believe that it is raining in the middle of a storm, or to doubt (the general rightness of) Newton’s law of gravity. These beliefs do not seem to be a matter of choice. On the other hand, there is a difference between understanding a proposition and believing it: we understand what it means to withhold our belief until sufficient evidence has been provided. And there are, sadly, people who do not believe scientific theories like evolution, or who claim that we did not land on the Moon. It is possible in principle, therefore, to deny or affirm anything: and that demands an explanation along the lines of the one Descartes offers.
Perhaps the most interesting category for Descartes’ claim is the sort of clear and distinct perception that is beyond doubt. It seems that Descartes believed that these perceptions could not, in fact, be resisted:
... the nature of my mind is such that I cannot but assent to these things, at least so long as I clearly perceive them. M5 p45
And later in the Replies:
Now some of these [perceptions] are so transparently clear and at the same time so simple that we cannot ever think of them without believing them to be true. OR2 p105 (emphasis added)
If we are not free to deny such clear perceptions, then this appears to be a limit to the will. Most of us would happily accept that there are such limits, but they present a problem for Descartes who insists that the will is infinite. Bernard Williams is sceptical – ‘Descartes’s view of the will as limitless is not fully intelligible’ (p174) – and it is hard to disagree. The philosophical objections to the concept of a completely free will are well known, but that seems to be the position Descartes is defending.
It is important to note, however, that freedom for Descartes does not mean having nothing influencing one’s choices. On the contrary, real freedom involves having good reasons to assent:
For in order to be free, there is no need for me to be capable of going in each of two directions; on the contrary, the more I incline in one direction—either because I clearly understand that reasons of truth and goodness point that way, or because of a divinely produced disposition of my inmost thoughts—the freer is my choice... the indifference I feel when there is no reason pushing me in one direction rather than another is the lowest grade of freedom. M4 p40
It is not clear whether such an account of freedom can be squared with the claim that the will is infinite.
Besides giving an account of error, Descartes has a second concern in this Meditation: to excuse God. In effect, he is providing a theodicy: where theologians need to account for the existence of evil in a universe created by a good God, Descartes needs to explain error.
His answer is strongly reminiscent of the theodicy of St Augustine. Augustine understands evil as a privation, a lack of goodness, in the sense that illness is a lack of health, or darkness an absence of light. Humans freely choose the worse path, and thus evil enters the world. The point of this account is to absolve God: evil is not a substance created by God, it is not a tangible part of His creation.
So Descartes defines error as ‘not something real which depends on God, but merely a defect’ (p38). Humans freely choose to assent to confused ideas, rather than restricting themselves to clear and distinct perceptions; in much the same way they freely choose the sinful path rather than choosing only the good. As Bernard Williams puts it:
... the operation of the will is the same, whether one is concerned with reasons of ‘the true’ or of ‘the good’. Williams p169
Descartes thus spends some time making it clear that a tendency to error is the result of his own imperfections, and God is not to blame:
As for the privation involved—which is all that the essential definition of falsity and wrong consists in—this does not in any way require the concurrence of God, since it is not a thing; indeed, when it is referred to God as its cause, it should be called not a privation but simply a negation. For it is surely no imperfection in God that he has given me the freedom to assent or not to assent in those cases where he did not endow my intellect with a clear and distinct perception; but it is undoubtedly an imperfection in me to misuse that freedom and make judgements about matters which I do not fully understand. M4 p42
The influence of Augustine is suggestive – although in the Synopsis to the Fourth Meditation he is careful to clarify the extent of his theodicy. ‘I do not deal at all with sin’, he writes – just in case readers confuse his account of cognitive error with traditional accounts of moral error.