How do we Know?

How do we Know?

Some things we experience directly – snow is cold. I know this because I have touched it. There are many things that we do not know in the same way, either because we have not yet experienced them ourselves or because they are not the sorts of things we can experience, for instance I know that the Sun is just under 150 million km from the earth. I will never travel that distance or experience it in any way but I can know it. In order to know these sorts of things some form of reasoning must be used.

Snow is made of frozen water, frozen water is cold, therefore snow is cold. This is an example of deductive reasoning that would allow me to know snow is cold even if I have never experienced it. It is the sort of reasoning that must give us the right answer as long as the assumptions (premises) are correct. If snow really is made of frozen water and frozen water really is cold then snow must be cold. I could say this even if I know nothing more about snow and have never experienced it.

Inductive reasoning is based much more on experience for example every time my wife watches the film 'Philadelphia' she cries. If we are watching Philadelphia again tonight I might say I know she will cry tonight. This knowledge relies on some sort of experience and is not quite as secure and certain as deductive reasoning, for example it may be that tonight my wife is not quite as saddened by the film as she has been in the past and does not cry.

You may think that inductive reasoning is not quite as good as deductive reasoning and in many ways you are right but it wouldn't be possible to know whether my wife will cry tonight with deductive reasoning. This sort of reasoning can’t really tell us anything new that is not contained in the premises, it simply rearranges them to help us realise something we may not have spotted before. To go beyond this we must use inductive reasoning.

Where does Knowledge Come From?

Where does Knowledge Come From?

There are two main ideas about where our knowledge comes from, each related to the types of reasoning mentioned before.

Rationalists such as Descartes, Leibniz and Kant argue that we can know things purely by using reason. We don’t need experience of the world outside us to have knowledge. For example as long as I have the concept of numbers then I don’t need any experience to know that 2+2=4. The most famous expression of rationalism is probably the quotation from Descartes – “I think, therefore I am”. In trying to ascertain what he could really know for certain, Descartes began with the starting point that, since he was thinking, he must exist. While it may seem obvious to you that you exist, it is rather harder to prove it but through simple (at least in hindsight) logic Descartes was able to prove to himself that he did. Rationalism is closely related to the deductive reasoning you have already read about. Assuming we have the basic tools of logic, maths etc. (which they claim we are all born with) rationalists argue that we do not need to have experience of the world around us to know things – we can deduce them from first principles.

Empiricists dispute that we are born with any innate knowledge or tools. Philosophers such as Locke and Hume would argue that knowledge comes primarily from experiencing the world around us and making inductive arguments from there. The most famous work on the subject is probably Locke’s “An essay concerning human understanding” in which he argues that there is no need to assume certain inbuilt tools as logic and maths as all our knowledge can be explained more simply by learning from experience. This allows much more knowledge than rationalism but does make certain assumptions, for example that we can experience the ‘true’ world around us, an argument we will consider later.

What is Knowledge?

What is Knowledge?

Now we have some background it is time to consider what we really mean when we claim to know something. It is a surprisingly slippery concept to nail down but traditionally philosophers have taken the so called ‘Tripartite’ view of knowledge. It has been expressed in many ways and dates back to Plato but the rough gist is that I can claim to know something if all of the following are true:

• I believe that it is true
• I have a justifiable reason to believe it is true
• I am correct to believe it is true

It is often summarised as: knowledge is a justified, true believe. This would seem to be a fairly safe working definition. Obviously if I don’t believe the earth is round I can’t claim to know it is. Equally I may believe it to be round but, without justification I am simply wishing. Even this definition has its problems though. What if, for example, my reasoning was wrong. What if I believed the earth was round only because I had seen a photoshopped image of it. I would be right but for the wrong reasons. Could I really then say I knew it. There are many adaptations of this definition that seek to solve the problem but each has its own issues.

One attempt to get away from the problem all together is to take a pragmatic view. A pragmatist (in the philosophical sense) argues that knowledge and understanding come about not by reasoning from basic principles but by working assumptions and experience. To go back to our snow example, we may not be able to prove exactly how I know or what it means to know that snow is cold but the fact that if I assume it is cold I use it to cool my drink and that works allows me to say that I know it is cold.

What can we Know?

What can we Know?

All we have said so far, except maybe the most basic parts of rationalism, assumes that there is a world outside that we can experience directly and know something about. Scepticism questions even this basic assumption. It suggests that it might just be possible there is no such thing as a ‘real’ world, it questions our very existence (and everything else along the way) and accepts only what can be certainly proved. Bertrand Russell points out that while it is hard to prove beyond doubt that we do not all exist in some Matrix style fabrication there is not the slightest reason to believe that we do. For those of us at risk of being driven mad by doubting even our own existence this is us useful fact to hold on to, however it is undeniable that our minds do not experience the world outside directly and so it is hard to say we know exactly what it is like.

Take the example of a table that Russell uses in his Problems of Philosophy. You believe the table in your kitchen is rectangular but from almost every angle it appears not to be – perspective makes it appear as a trapezoid looking along its length, from a corner it may look like a diamond etc. The colour is no less problematic. You think it is brown wood but place it in the sunlight it will look white in places, or blue, reflecting the sky. Touch is no less problematic. You hit the table and think it hard, solid, but an electron microscope tells us that the table (and your hand for that matter) is mostly empty space between tightly packed nuclei of atoms and fast moving electrons. All this is to say that your mind interprets what the ‘real’ object is like but how do we know whether we have the ‘correct’ interpretation? We have all seen optical illusions that fool our mind. What makes us sure that there is a ‘real’ world at all, rather than a collection of ‘sense data’ generated some other way?

Conclusion

Conclusion

If you have made it all the way to the end you have done well – it is not easy stuff the first time you come across it. The intention of these articles is not to teach you an exam syllabus or prepare you for a test, it is to give you an introduction to some of the key areas of philosophy, especially if you are considering the subject as part of a university course. Now you have a little understanding of the key areas such as rationalism and empiricism, inductive and deductive reasoning and scepticism, you are better equipped as you read books and articles to understand the basic terminology and what some of the arguments are driving at. If you are preparing for an interview or personal statement you might want to try reading Philosophy – Key Themes by Julian Baggini or, slightly less accessible but free and well worth the effort, Problems of Philosophy by Bertrand Russell. You might also want to have a look at our "Guide to Good Thinking" for a non-technical approach to knowledge or our “Writing a Personal Statement for UCAS” blog post for thoughts on statements and interviews.