Shaping the world with the mind

Intro: Immanuel Kant recognised that while rationalism and empiricism presented opposing claims, both contained elements of truth. He argued that while we know the world through our senses, it is shaped by our minds

Representation of things

Kant (1724–1804) sought to establish the limits of what we can know about the world. Unlike his predecessor, John Locke, he argued that experience alone was unreliable: not only are we limited to our particular sense organs, when we do perceive something, we only perceive a “representation” of that thing in our minds, rather than see the thing in itself. A rose, for example, may appear red or grey to different animals, and so is only ever seen indirectly, as a construct of our senses.

Kant also argued that our psychological make-up shapes the world we perceive. Our minds are so constructed, he said, that we perceive things in terms of space and time, and that anything outside these parameters is beyond our understanding. He claimed that in a sense we project the concepts of space and time onto the world, and then perceive the world accordingly. A child, for example, learns the concepts “here” and “there” through experience, but it only does so because it innately understands the concept “space”. Likewise, the child learns the concepts “then” and “now” because it has an innate understanding of the concept “time”.

Transcendental idealism

Kant argued that innate concepts are what make experience possible, and he identified 14 such concepts. They are like lenses through which we both project and view the world. Kant was therefore neither a rationalist nor an empiricist – that is, he saw neither reason nor experience as our primary source of knowledge. He described his position as “transcendental idealism”.

The Noumenal World

Kant compared the way we perceive things to the way a painter presents an image of something. A painting may portray every detail of a scene, but it remains merely a representation of that scene, not the scene itself.

In the same way, our perception of an object is a mental representation, not the object as it actually is. We experience only the “phenomenal” world, which is accessible through our senses, but can never have direct access to what he called the “noumenal” world of things-in-themselves.

Categories of understanding

According to Kant, when we perceive an object, we shape it with our innate ideas of space and time: we project these ideas onto the object and then interpret it in those terms. He described space and time as innate “intuitions”, and distinguished a further 12 concepts, or “categories”, which he also claimed we understand innately and project onto what we perceive. He classified these into the four divisions of quantity, quality, relation, and modality.

. Quantity [Unity, Plurality, Totality]. These categories enable us to distinguish single things from many things, and to perceive many things as parts of a whole.

. Quality [Reality, Negation, Limitation]. Such categories give us the notions of something being real or unreal, and that of something having an extent or limit.

. Relation [Inherence/subsistence, Causality/dependence, Community/reciprocity]. The categories of relation enable us to perceive the properties of an object and to understand its relationships to other objects.

. Modality [Possibility/impossibility, Existence/non-existence, Necessity/contingency]. The modal categories enable us to know if something is possible or not, whether it exists or not, and whether it is necessary or not.

KINDS OF TRUTH

At the heart of Kant’s transcendental idealism is the idea that it is possible to have knowledge of the world independently of empirical evidence or experience.

A priori and a posteriori knowledge

Before Kant, many philosophers had realised that there are two kinds of truth: necessary truth and contingent truth. A necessary truth, such as “Circles are round”, is one that is true by definition, and so cannot be denied without contradiction. A contingent truth, such as “The sky is blue”, is either true or false according to the facts. Kant introduced two similar distinctions: firstly, between analytic and synthetic statements, and secondly between a priori and a posteriori knowledge.

An analytic statement, like any proposition, consists of a subject and predicate, but its predicate is implicit in its subject. For example, the statement “A square has four sides” is analytic because its predicate (“four sides”) is implicit in its subject (“square”), and so it is true by definition. Synthetic statements, however, have informative predicates, which tell us something new about the world. For example, “This square is red” is synthetic, because its predicate (“red”) is not contained in its subject (“square”).

Kant also identified two different kinds of knowledge: a priori knowledge, which is known independently of experience, and a posteriori knowledge, which is known through experience only. These two kinds of knowledge are expressed in analytic and synthetic statements respectively.

Kant also claimed that there is a third kind of knowledge: synthetic a priori knowledge, which is both necessarily true (a priori) and informative (synthetic).

Synthetic a priori truths

Before Kant, it was assumed that all a priori knowledge must be analytic – that is, if it is known without any empirical evidence, then it cannot tell us anything new about the world. However, Kant claimed that from a priori statements we can make deductions that are synthetic, and so tell us something about the world. Here’s some examples:

. Synthetic A Priori – “The interior angles of a triangle add up to 180 degrees.” This statement tells us something about a triangle that is not implicit in its definition, and is therefore synthetic. However, it is also an a priori truth, since, for Kant, it can be arrived at through rational reflection.

. Analytic A Priori – “A triangle is a three-sided shape.” This statement is analytic: the definition of its subject, “triangle”, is a shape with three sides. It is also an a priori truth, since we understand it without empirical evidence.

. Synthetic a priori judgements – According to Kant, we are born with no knowledge of the world, but we do have innate concepts that enable us to experience the world intelligibly. For example, we have a priori knowledge of the concepts of space, time, and causality, and these enable us to arrive at scientific and mathematical truths that are both synthetic (informative) and a priori (necessary). For Kant, the statement “3+3=6” is a synthetic a priori truth, because it is informative (it says more than “3+3=3+3”) and can be arrived at through reason alone.

. Philosophy: Modern Logic