Why do philosophers raise these kinds of issues about perception, thinking, and the nature of our world? Are they not satisfied with seeing the world as it is without making it more complicated? What is the original impulse to their questions?

Generally, questions are catalysed by a state that we call doubt. Perception produces doubts. We have a doubt when we see something in the distance and we are not able to decide if it is a person or a tree. To use another famous example that is discussed quite extensively in Indian philosophy: you see a shape on the ground but you have doubt whether it is a rope or a snake. When we hear something, there is often a doubt whether we heard it “correctly”. Or sometimes we have powerful dreams and then have a doubt whether we had a dream or whether that event really happened.

Doubt is of special interest to philosophy. One can even say that for some philosophers it is the starting point of philosophical reflection. Therefore, it is not a surprise to find that philosophers across different traditions focus on the notion of doubt. The belief that doubt is an important step towards knowledge makes the category of doubt more important since, arguably for most traditions of philosophy, an important goal is to reach a state of knowledge. (There may be other goals in addition to attaining knowledge, such as compassion for the Buddhists, liberation for theologically minded philosophies, right action for some others. In many of these traditions, knowledge itself is seen as a way to reach higher goals. We should also remember here that what we mean by knowledge itself is a philosophical project since there are different kinds of knowledge.) Doubt is associated with a state of uncertainty, and knowledge with certainty. Believing, having opinions, and guessing are cousins of knowing, and these terms are characterised by a sense of uncertainty.

The movement from doubt and uncertainty to certainty is an important catalyst for thought. The definition of philosophy as resolving doubts and leading to a state of knowledge is a theme that resonates from the ancient Indian and Greek traditions to modern philosophies.

The Nyāya school is one of the oldest philosophical schools, and known for its work on logic. The foundational text of this school, dated around second century BCE, is the Nyāyasūtra, which is a compendium of verses. The first verse in this text defines philosophy as a sixteen-step process that moves from perception, doubt, logical analysis and ultimately to certainty. These sixteen categories encapsulate the many elements of philosophical thinking in a succinct manner. It would be difficult to find any such equivalent description elsewhere. (A longer discussion on these categories will appear later in the book.)

The philosopher who is most famously associated with doubt is Descartes. For Descartes, doubt was a methodological tool for inquiry. The fundamental doubt for Descartes was the doubt about one’s own existence. Methodological doubt is a sceptical way of doubting everything until you come to a point which cannot be doubted since it is self-evidently true. For Descartes, this point is encapsulated in the famous phrase Cogito, ergo sum: I think, therefore I exist. The point for Descartes was not merely to resolve doubt, but to use doubt as a method to produce knowledge that is characterised by certainty. Immanuel Kant considered doubt as absolute and as a path to knowledge, which for him was also associated with certainty. He distinguished between two types of doubts, objective and subjective doubts.

The Buddhists classify doubt as one of the five hindrances in the mind, which cause emotional unease in a person. Many Buddhist approaches to doubt focus on its psychological consequences and point to mindfulness and meditation as ways to conquer doubt. In this sense, doubt for these philosophers is not like the sceptical doubt of Descartes or doubt as described in Nyāya, Kant or the pragmatists. But the Buddhist approach is important since it emphasises philosophy as a life-practice that has implications for how one leads a life, rather than merely an intellectual exercise of clarification and reaching a goal of certainty in thought. In religious traditions, doubt is seen as the greatest obstacle to recognition of the truth, and so faith is often counterposed to doubt. There is a long tradition of Chinese philosophers, such as Lao Tzu, who have propounded a path of doubting everything in the sense of a method.

Thus, doubt seems to be widely accepted as a fundamental quality of human thinking. This theme can be an entry point for our own philosophical thinking about doubt. For example, how do I know that I am in a state of doubt? Is it a state of unease? Is confusion and indecision a reflection of doubt? Is doubt a reflection of ignorance? What is it to live in a state of uncertainty or of absolute certainty?

It is important to recognise that there are different types of uncertainties in our experience, so perhaps it is not ideal to find ways to remove these uncertainties. To read philosophy is to critically reflect on what is being said by these philosophers. They may give different ‘theories’ about doubt, but do these descriptions match our experiences? Can we use these insights to understand our own experiences of doubt in a better and deeper manner?

I would say that the category of certainty is itself something of a problem. In Western philosophy, certainty is modelled on mathematical knowledge. Mathematics has been the dominant influence on Western philosophy. Mathematics is characterised by absolute certainty in its formulations. 2 + 2 = 4 is a classic example of knowledge that is absolutely certain and unchanging. It is universal in that it is the same for all of us. Western philosophy is deeply influenced by this capacity of mathematics, and this influence continues till modern times. This influence can be seen strongly not only in Plato, but in influential philosophers like Descartes and Leibniz, who were mathematicians themselves. Their attempt was to bring in the quality of mathematical certainty into philosophical discourse.

In contrast, the idea of certainty of mathematics is not that which influences non-western traditions, including the many Indian schools of philosophy. This in itself is a fascinating subject for study, particularly given the fact that mathematics was far more developed in India and China compared to Europe in the mediaeval era. Thus, one could say that the notion of certainty for Descartes is qualitatively different from that of the Nyāya philosophers. Certainty could be with respect to propositions that are absolute and unchanging, or it could also refer to actions, such as knowing with certainty how to act in a given situation.

Although doubt is a state of uncertainty, it nevertheless has some reason as its basis. Suppose I have a doubt whether the tree that I see now is really in front of me. Why would I even have this doubt? There are actually many reasons for doing so, such as the following: maybe the tree is an illusion, maybe it is a hallucination of a fevered mind, maybe my eyesight is tricking me, maybe it is a picture that somebody has placed in front of me, maybe I am dreaming.

Sometimes, we can start doubting without really having a doubt. Doubting as a method can sometimes lead to this state. Scepticism, which has a long history, is a school of philosophy which questions everything. It takes a quality of human thinking and uses it not as a means to some other goal but as an end in itself. A constant sceptic who questions everything that others say or do can be tiresome, but as an intellectual method it has some benefits.

Nyāya philosophers offer an interesting formulation about the nature of doubt. They point out that doubt is contrastive. This means that the question arising from doubt is of the form ‘Is this p or q?’ It is contrastive because doubt arises when there is more than one possibility, p or q. Doubts about our own actions are often of this form: should I join this college or that? Should I buy this dress or that one? The contrastive nature of doubt makes doubt more aligned with the experience of doubt. In our most common experiences of doubt, we do not start by doubting something unless there is a reason for it. A common reason is the possibility of alternatives. The Nyāya argument might suggest that doubt will arise only if there are potential alternatives. The question of doubt, and related to it theories of error, were an important part of the different Indian philosophical traditions. We will consider some details of them later.

Radical, sceptical doubt or doubting just to doubt is not a ‘real’ state of doubt. Nyāya philosophers, Buddhists and even pragmatists like Peirce, acknowledge this because they realise that doubt has an important function. The reason why we are all not sceptics is because doubting is related to action. It cannot be reduced merely to a mental exercise. Once we have a doubt, the next step that we take is to consider how that doubt can be resolved. In our everyday lives, doubting is often associated with action. Doubt arises not merely in perceiving the world and our surroundings, but also when we need to act.

Suppose we see a form on the ground and there is a doubt whether it is a rope or a snake. We are not paralysed with doubt nor do we see that merely as a mental exercise. We can pick up a stick and try to find out what that object is. This is true even in the case of doubts about mental actions, such as calculation. The conversion of scientific knowledge to technology is a reflection of this capacity of action to resolve doubts about the truth of that knowledge.

Doubt’s relation with action brings the individual and the social world directly into an analysis of doubt. There is an interesting structure to resolving doubts that becomes a methodological way to understand philosophy. This is the introduction of the idea of debate. Debate should be seen as an important methodology in philosophy. Indian schools of philosophy were always in a constant debate that challenged each other’s positions. These philosophies accepted a clear structure of debate, rules according to which one could defend one’s position, and norms by which one could objectively declare the loser in the debate. There are many interesting stories about debates in ancient Indian philosophy, particularly among the Vedantins, Buddhists as well as Jaina philosophers.

Three common types of debates have been discussed in the literature. One is the debate between a teacher and a student, where the aim of the debate is to learn something. The second is a debate that uses various kinds of quibbling and rejoinders in order to win an argument. The third kind of debate is what happens in our media today: the aim of the debate is only to stick to your point and use whatever means are available such as shouting your opponent down or attacking them personally. These three forms of debate are called vāda, jalpa, and vitanḍa respectively. In the Greek tradition, strategies of argumentation, such as those used by the Sophists as well as a larger sense of dialectical reasoning including the Socratic method, were integral to the practice of philosophy. In China too, debates were an essential part of reasoning, as exemplified in the practice called Biàn, although their styles of debate as well as the intent of debate differed, for example, from the Indian traditions.

The use of debate as a method of argumentation continues into philosophical practice today. Sometimes, for some schools of modern philosophy, debate and arguments have become the end goal. To think about another story of philosophy is to think through all the assumptions and practices of the received stories of philosophy.


Other articles in this series

Sundar Sarukkai on how philosophy can be a living tradition in our lives today

‘Do we perceive the world or do we think it?’ Sundar Sarukkai on thinking in philosophy

‘Philosophy is an act of illuminating the invisible’: Sundar Sarukkai on human perception


Another Story of Philosophy will be published by Westland Books. Sundar Sarukkai’s recent books include Philosophy for Children, The Social Life of Democracy, and the novel Following a Prayer. For more details, see the author’s website.