Knowledge is one of the big topics in philosophy — the discipline within the field is known as epistemology (which comes from episteme, meaning knowledge and logos, meaning word, reason or plan).

Then how do we define knowledge? One great definition you can find inJulian Baggini’s and Peter S. Fosl’s book The Philosopher’s Toolkit, where they point that that it isn’t just believing in something (after all, I could believe in pink unicorns, but it doesn’t necessarily make them true creatures or that the majority of people will agree about my belief). So, we have to factor injustifying the belief, and what can be found to be true about it.

This is where our senses and experiences come into play — but we also know that our senses might not be trusted or can be limited. We can have realistic dreams, hallucinations, be influenced by illusions after all. This illusion argument challenges whether or not we can be certain of reality at all. And then there’s the question as to whether we’re in something like the movie The Matrix, just an organism in a jar, being fooled by a fake reality, merely a brain in a jar. How do we reliably know anything about the world at all then?

There’s a number of philosophers who investigate knowledge — some famous ones include the seventeenth-century French philosopher René Descartes (1596–1650) is famous for his work Principles of Philosophy, where we get the claim ‘I think therefore I am’ (cogito ergo sum). We are thinking, therefore we exist. And that is the basis of understanding ourselves and the world around us and various concepts.

Philosophers like A. J. Ayer (1910–1989), argued that it should be clarified further — just because there is thinking, doesn’t necessarily mean there’s a thinker attached! There’s a number of arguments about how we can truly know things, and that will be the focus for the rest of the week. Further links on the topic can be found at www.365daysofphilosophy.com.