As Russell asks: “Is there any knowledge in the world which is so certain that no rational man can doubt it?

Introduction – Types of Knowledge

In answering this question of epistemology I will critique the arguments of various philosophers as well as include my own arguments. I will argue that there are different types of knowledge and that some are more ‘easy’ to obtain than others and that obtaining knowledge of all the types is possible.

For a long time knowledge was defined as a, “true justified belief”. This was until Edmund Gettier proved that there can be situations when a person can hold a true justified belief but still be wrong. He showed that someone could be right for the wrong reasons even if they have a justification. Richard Kirkham responded by making the case for infallibilism. He plugged the hole that Gettier created by saying that as long as a persons justification was infallible the person had knowledge. (

I am born knowing how to breathe, how to blink, how to cry. These are examples of innate knowledge, or instincts. They do not require any belief. We toss around the phrase, “I do them without thinking,” but really there is pre-programmed brain activity going on running the show for us. It is impossible for me to hold doubt about knowing how to do these things unless I was insane. I could be deluded into thinking I a pickled onion, yet my lungs would still breathe. This is the first type of knowledge that any rational man believes.

Knowing how to ride a bike is a commonly mistaken example of knowledge that does not require belief. In order to learn how to ride a bike and put our feet on the pedals we must trust our senses that we are looking at and touching a bike with pedals, and not a hot air balloon with a basket with which we need to put a leg over. Even so, once learned, knowing how to ride a bike joins the category of things a rational man cannot doubt. I cannot even entertain the possibility that I cannot ride a bike.

Another type of knowledge is unconscious knowledge. Teichman and Evans (1999, 52-53) claim that, “everyone knows things they have never thought about.” They give the example that, “You know you are not descended from a marriage between and oak tree and a tortoise.” They say that I can know this because I know who my actual parents are. This argument can be put into a deductive form:

My parents are Steve and Joanna Neither Steve or Joanna are a tortoise or oak tree

Therefore I am not descended from the marriage of a tortoise with an oak tree

Teichman and Evans explain, “this unconscious knowledge concerns facts, often negative in character, which logically follow from other, consciously known facts.” Because I had never thought about this scenario before I cannot hold a belief about it. A belief was required earlier in knowing who my parents are but not for the negative version. Therefore negative unconscious knowledge does not always require belief and providing it is simple enough to perceive all at once (such as the example) it cannot be doubted, because in doing so the original piece of knowledge would be called into question and if that is already deemed true then so is its opposite.

This view does not mean we know all the infinite degrees of opposites that exist with the knowledge we hold, for example:

I know a route from my house to the station I do not know every route

Therefore I do not know if my route is quickest.

The Cogito and Dreaming – showing there is an external reality

Everything has a cause. According to Descartes (Michael Moriarty, 2008) this is a clear and distinct perception, which means that while it is held in the mind it cannot be logically doubted. Our thoughts have a cause. We are not ‘giving birth’ to thoughts. Therefore there must be something external. Our senses may be wrong about what it is, and our intellect wrong in disentangling the data, but there is something out there. Descartes’ cogito ergo sum (I think therefore I exist) can therefore be extended to “I think, therefore I exist, and so do stimuli.”

But what about in a dream? Descartes asks. I would reply that the memories are the stimuli, but the memory has to have been formed somewhere during a conscious reality, otherwise the thoughts would be coming from nowhere.

A human by definition means a person with a physical brain. That is part of a sound definition and therefore to deny that is to say that all sound definitions I contain could be wrong and thus everything I think could be wrong. If all I am is a thinking thing that has entirely wrong thoughts, how do I still exist? Should I still exist?

Virtual Reality Analogy showing knowledge being possible

Another way to view knowledge is as a tool with which our realities are created. Increased cognitive powers would allow me to use more data at once to create more specific knowledge and enrich reality. For example, an old 8bit computer game may show a character on the virtual reality screen. The programmer of the computer game is the stimulus or external reality. The on-screen character is the computers representation of reality, but because it lacks processing power (intellect) and memory (memory). This results in the pixels being clearly visible. However, the on-screen character is clearly a representation of a person, the head is above the shoulders and the feet are at the bottom. The computer has the files, albeit only a few of them, to tell it how this part of its virtual reality should be. It knows that is how a human body is, even if it doesn’t call its file the same name.

If we now look at a modern computer game with a new on-screen character. The character doesn’t quite look the same as our senses would tell us that he would appear in reality, but it is much more convincing. You can see the shoes on this character, and his belt and his clothes. This computer knows more, it has more data and it is processing it more efficiently and more accurately. This is how our senses and intellect work together to create our reality.

Russell’s table looks brown, but we, being relatively advanced computers recognize that its appearance changes depending on the light ( We can see that zooming in with a microscope shows us something different. We are still seeing the table, only from a certain perspective and filtered though our senses. These complications such as noticing a slight difference in the table’s surface are a reason to trust our senses not to doubt them because they are a sign of advancement and increased powers of knowledge.

Perhaps, in the mind of a small-brained squirrel reality is simpler, more like the virtual reality of the 8bit computer game. At least some of what it experiences and believes will be true and infallibly justified and is therefore knowledge, such as it knowing where it buried its nuts.

The abilities of our senses can and will be increased. If I put on night vision goggles I experience a reality similar to that of certain nocturnal animals. With the risk of sounding absurd, X-ray glasses, infra red vision goggles and numerous other futuristic creations are adding to our senses arsenal, each providing a strong back up that our senses are indeed making some sense of the external world.

These ideas suggest that our reality is made up of our knowledge and because we exist in a reality made up of many different things we must have many different pieces of knowledge.

Symbols and Innate Knowledge

To deny existence of dimensions is to deny comprehensible existence. If there is indeed innate knowledge other than knowing how to perform basic bodily functions, it is not of numbers, it is of spatial dimensions. Numbers are to do with the intellect becoming advanced enough to divide up dimensions. For mathematics to make sense there must be dimensions for 2+2 = 4 to apply to. Mathematics is symbolic of reality. I consider myself to know that 2+2=4. Therefore if maths is not innate knowledge as I have outlined, but something put together by the intellect from data gathered by sensory perceptions, then knowledge of the external world is possible and the extension of trusting maths to trusting science is rational.

Descartes writes in his first meditation (Michael Moriarty, 2008, 15) about maths being trustworthy and he claims that medicine and physical sciences not because they rely on sensory data. As I have explained maths cannot be grasped without understanding the concept of there being a ‘thing’ to divide up, multiply or add. 2+2=4 does not innately make sense. 2 pebbles + 2 pebbles does make sense but it requires experience and is a priori knowledge. Humans have learned to conceptualize and symbolize allowing maths to refer to an unnameable substance.

Additionally, maths is a symbolic language we have created. If I create something, or imagine something I have the power to say what is true about it. I know about my own creations as a God knows about its.

The Universe and God: Showing knowledge is guaranteed

Russell ( how Bishop Berkeley explained that a “tree must continue to exist even when we shut our eyes or when no human being is near it. But this continued existence is due to the fact that God continues to perceive it.”

In many cases of reading philosophical texts I find this usage of the word ‘God’ perplexing. Should it not be replaced by “The Universe”? I.e. The tree can continue to exist because The Universe and all its natural forces continue to exist. Bishop Berkeley is personifying the Universe by saying there is a being with a mind similar to ours perceiving the tree, which he then uses to claim, “apart from minds and their ideas there is nothing in the world.”

Furthermore, Descartes claims an Atheist cannot truly know anything as neatly summarized by Bernard Williams (1978, 188):

“It looks as though reliance on our clear and distinct ideas does need a justification, and that this is provided by God.”

I will now explain why both Descartes and Bishop Berkeley are wrong.

The following argument refutes Descartes and his arguments regarding God:

God and the entire physical Universe is the same thing We exist in the physical Universe

Therefore were are part of god and by knowing we exist we know god and can know other things.

Problems with trusting maths and science

We may all have the capacity to know that 2+2=4 but we cannot all have performed all the experiments that prove, for example, that our DNA is what programs our cells to turn us into fully grown human beings. Unless we are an expert in a particular field we are left to trust someone else’s clear and distinct perception. We may have a justification why we should trust the scientist, but how far down the chain can we remain certain?

Using my previous ideas, we innately know how to exist. Our innate bodily functions are part of that, so is the instinct to eat and learn how to do things. Forming beliefs is another one of these functions and is therefore unavoidable and we are doomed to have some level of inaccuracy and accuracy.

Any rational thinker would surely agree that the ability to imagine complete nonsense does not mean the nonsense is possible, given we also have the ability for rational judgement.


To summarize, I have analysed the arguments of respected philosophers and found some of their thoughts to be right and other thoughts wrong. I have explained that there is innate know-how knowledge, which even if a person tries to doubt it, the mind performs the functions anyway. I have explained how there are other forms of know-how knowledge, which can be proven simply by doing them. I have used an analogy to argue that knowledge is used by our minds to form our reality and that because we live in a reality we must have knowledge. I have also explained how our logic can be trusted using maths as a foundation. Therefore a rational man must agree we can have knowledge of:

Our own existence There being an external reality and many aspects of it. Instinctive innate knowledge Mathematical sciences

Overall I have explained how we are tied to our external reality through our senses and that they are sometimes inaccurate, but we can trust them and our intellects to a pleasant degree for everyday living.


Bernard, W. (1978) Knowledge is Possible, Chapter 7 of his Descartes: The Project of Pure Inquiry, (Penguin)

Epistemology, Wikipedia,

Jenney Teichman and Katherine C. Evans. (1999) Philosophy A Beginners Guide, Third Edition, (Blackwell)

Descartes, R, translated by Michael Moriarty, (2008) Meditations on First Philosophy with selections from the Objections and Replies, (Oxford University Press)

Russell, B. (1998) Problems of Philosophy,

Russell, B. (1998) Problems of Philosophy,


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