Anyone who reads philosophy will inevitably bump into certain terms that will cause consternation and distress. Eight of these are; Idealism, Materialism, Rationalism, Empiricism, Realism, Nominalism, Dualism and Monism. Just reading them induces stress. And as you begin to understand what they mean you find out why. Some of them seem to mean almost the same thing and are used interchangeable even though they are not the same. Some sound exactly like what they mean and others sound like the opposite of what they mean. The meanings of these terms are separated by subtle distinctions and partly because some of them have both a technical philosophical meaning and a more common meaning that seem to conflict.
So for the sake of would-be philosophy enthusiasts everywhere let’s walk through them slowly.
First of all of these terms are in a general way related to one of the most foundational philosophical dualisms there is – mind and matter. At least since the ancient Greeks the problem of mind and matter, thought and thing, the spiritual and the material, has existed. And as long as that dualism exists the fundamental question that needs to be tackled is, “Which is more real – mind or matter?”
Idealism is the belief that the mind and ideas are the primary structure of reality and that physical or material reality is secondary.
Materialism is the opposite of Idealism and sees matter as the primary reality and all other things including thoughts as the product of interactions of matter.
Rationalism is the belief that the rational mind is the best way to know something. If you are a rationalist you believe that your mind is more trustworthy than your sense. A stick in the water might look bent, but you know rationally that it only looks that way because it is in the water.
Empiricism is the opposite of rationalism and it is the belief that the senses are the best way to know something. You might think something is true, but you only know it is true if your senses confirm it.
In consideration of the above it is good to keep in mind that you can’t be an Idealist and a Materialist and you can’t be a Rationalist and an Empiricist.
On the other hand, you can be an Idealist and a Rationalist or an Idealist and an Empiricist. You can also be Materialist and a Rationalist or you can be a Materialist and an Empiricist.
That is because Idealism and Materialism are statements of ontology which means they are statements about what you believe is real. Rationalism and Empiricism are statements of epistemology which means statements about what is the best way to know what is real.
As if this were not confusing enough we also have Realism and Nominalism.
Realism is the belief that there are real existing entities behind universal or general ideas. For instance there is a “thing” called justice.
Nominalism is the opposite belief that these general ideas are not real things but names that point to real things. There is no such thing as “justice”; the world justice is just a name and only the individual instances of justice are real.
Now for our last two terms we have Dualism and Monism.
Dualism is the belief that mind and matter represent two different and distinct types of being.
Monism is the belief that there is ultimately only one type of being. A onist could be an Idealist believing that everything is made of mind or ideas including matter. A monist could also be a materialist believing that ideas are ultimately products of matter.
Ok, now for the one paragraph recap…
If you believe that the universe is made up of mind you are an idealist, if you believe it is made of matter you are a materialist. If you believe that best way to know something is to think about it you are rationalist, if you believe that the best way to know something is to experience it you are an empiricist. If you believe that ideas are real things you are a realist, if you believe that ideas are only names of real things then you are a nominalist. If you believe that mind and matter are two different kinds of things you are a dualist, if you believe that one of them is really real and the other is made of that one that then you are a monist.