Methodic Doubt, Cartesianism, and Realism

What is methodic doubt? Roughly speaking, methodic doubt can be described as the systematic rejection (or at least suspension) of all beliefs or claims on reality that is not ultimately grounded upon truths that are self-evident. It is systematic insofar as it tries to be consistent, and pursues the truth in an unbiased fashion regardless of where it leads or reveals itself. Methodic doubt puts its trust in the workings of reason alone. Methodic doubt’s rejection of ungrounded beliefs or ideas is not categorical in the sense of never allowing them to reemerge as candidates of truth in the future, but is rather a temporary rejection. These ideas may be taken up again or proven to be true later on, but only after having been refortified on the rock of certainty. Finally, by self-evident truths, proponents of methodic doubt may mean one of two things: 1) that which cannot even be conceived or imagined to be false, or 2) that which we do not have any sufficient reason to doubt and do have every reason to accept. One cannot mean both at once, at least not practically speaking. If one is to go about using methodic doubt in philosophical reasoning, one must fall into one camp or the other, not both (unless one is to fall into contradiction). It is this division of the different ways of looking at the self-evident or the starting points of philosophy that ultimately divide the various historical systems of philosophy into two.

One way of doing philosophy begins with, as its foundation, those ideas or beliefs that cannot be thought or even imagined to be false. Whatever our mind believes to be true, however natural this belief may be, must be scrutinized and put to the test of, what I will call, methodic doubt of the imagination, or imaginative doubt. According to this theory, until one stumbles upon some truth that one cannot imagine to be false, one cannot claim to know anything. This way of doing philosophy is perhaps best represented by the Cartesians, who historically grounded all knowledge upon the apparently indubitable awareness of the existence of a thinking process, or stream of consciousness if you like. They then derived, in a sort of inference or logical reasoning that if there is a process of thinking, there must be some underlying substance or being that undergoes this process. This is the “I” or “self” that is shown to exist in the famous statement: “cogito, ergo sum.”

The second way of doing philosophy begins, as mentioned before, with those ideas or beliefs that we are naturally inclined to accept as true and against which no evidence has been presented to shake their acceptance. According to this way of philosophizing, no rational non-philosopher denies the fact that there is an extra-mental world and that our senses are a source of knowledge. This trust in the senses and in the reality of the outside world is natural to man. It is the default position of humanity. And since, according to this view, there is no experience of ours or logical argument that contradicts this natural inclination, there is no reason to reject it and every reason to hold to it. This philosophy has been the most thoroughly presented by Aristotle and his followers, and is usually referred to as realism. I will call (at least for the present purpose) the type of doubt that is used in realism, realistic doubt.

Looking back upon these two ways, we immediately see how fundamentally different they are. This is even more apparent when one sees the dissimilar conclusions that logically follow from each. It is evident, therefore, that they cannot both be valid methods of philosophy. They are not two distinct paths to the same truths. Either imaginative doubt or realistic doubt is correct, not both. How then, are we to decide between the two? Will it be based upon some whim? Is it merely up to the individual to say: “I like realistic doubt. It feels right to me.”? Or can there be a rational justification for choosing one over the other? It is the purpose of this essay to attempt to answer this last question.

One easy way of revealing the incorrectness of a method or idea is to show that it contradicts itself, i.e. that it is self-refuting. If the adoption of an assumption leads to its own annihilation, then it is clear that the assumption was false. Now since imaginative doubting holds that anything that we can imagine to be false must be rejected, it follows that the idea that the intellect is capable of grasping reality and come to knowledge must itself be rejected. For the opposite is certainly imaginable. It is certainly possible that the intellect is an entity that is forever deceiving itself. Further if anyone objects to this, one could merely dismiss the objection as being a product of a broken machine and not to be taken seriously. In fact any thought, according to this hypothetical situation, that comes forth from the human intellect would be absurd, including this sentence. Certainly the validity of imaginative doubting, since it is a method developed by the intellect, would be in question. Thus the systematic application of imaginative doubting bankrupts itself. It doubts itself into absurdity.

Realistic doubting, on the other hand, does not lead to its own demise. For it can be shown through numerous examples and by reflection on our own manner of thinking, that this is the natural way of reasoning about the world. How could it be otherwise? We would have to say that we do not naturally accept to be correct the methodic doubt which demands that we accept those ideas or beliefs that we are naturally inclined to accept as true and against which no evidence has been presented to truly shake their acceptance. Thus realistic doubt is the correct method of doubt.

Now a Cartesian could still attempt to avoid “falling” into Realism in two ways. By using realistic doubt, he could conclude that the existence of the thinking self is the only natural belief. Or he could use realistic doubt to conclude that the existence of the thinking self is the only natural belief that is immune from evidence that hinders its acceptance. The first way would be laughable, since there are clearly many other things (including the exterior sensible world) that we naturally accept to be real or true. The problem with the second way, however, needs a little more explanation. The immediate response of a Realist should be the ask the Cartesian why he thinks this, or better yet why sensation and apprehension of the exterior world should be rejected. What evidence is there that “shakes” our inclination to trust the senses? Remember that the Cartesian cannot escape by using imaginative doubt, since that was shown to be an illegitimate method of rational discourse. A good Cartesian could only respond as his master did, by saying that sometimes his senses deceived him, therefore they cannot be trusted. The Realist would then immediately note that in order to know that our senses sometimes deceived us we would have to admit that there are times that the senses do not deceive us and that we are capable of telling the difference. If we were not able to tell the difference between being deceived and not being deceived, we would not be able to make the claim that there are times that the senses do deceive us. Further, the only way we could tell that the senses have deceived us would be to refer or compare the deceptive experience to a time when our senses did not deceive us. Thus it is impossible to provide evidence against the trustworthiness of the senses without at the same time admitting the trustworthiness of the senses. Thus Cartesianism is trapped. It cannot escape Realism via imaginative doubt, nor via realistic doubt. It then seems that Cartesianism has no rational foundation at all, and consequently leaving Realism as the only path to knowledge.