A level philosophy - impressions and ideas

Perceptions of the mind:

There is a difference between an actual experience and the memory of that experience.
Memories of the experience are less strong - “The most lively thought is still inferior to the dullest sensation”
Imagining a situation is less forceful that actually being in that situation.

E.g. A man in a fit of anger is very different to a man who is just thinking about that emotional state.

When we are reflecting on our past, our thoughts are like a mirror which accurately copies our objects and sensations, but they are still fainter.
Classes of Perceptions
All perceptions of the mind can be split into two categories
If perceptions are lively and forceful, we call them IMPRESSIONS - e.g. when we hear, see, feel, love, hate, desire etc.

Thoughts or IDEAS are the less forceful perceptions.

Imagination The imagination is “not restrained within the limits of nature and reality”
“To form monsters costs us no more trouble than to conceive the most natural and familiar objects”

Restricting the imagination:

Our imagination is really more limited than we first thought.
All the materials of the mind come from outward (senses) or inward sentiment (feelings) - although the imagination can alter these.
Impressions give simple ideas. From which we can create complex ideas.

The mind just adapts impressions in one of the following ways:
Compound (put together)
Transpose (move around)
Augment (make bigger)
Diminish (make smaller)

Hume’s examples: A golden mountain (we haven’t experienced it, but we have experienced ‘gold’ and ‘mountain’)
A virtuous horse.

Proof: Argument 1

All complex ideas can be broken down into simple ideas, which can then be traced back to impressions.
E.g. The idea of God comes from reflecting on human qualities (goodness, wisdom, intelligence)

Proof Argument 2

If someone doesn’t have the impression, or the sensory apparatus to have an impression, then they cannot form the idea.
“A blind man can have no notion of colour, nor a deaf man of sounds”

The missing shade of blue:

Hume asks us to imagine a man who has gone through life having experienced every shade of blue except one.
If these were lined up together, with a gap for the missing shade, the man could formulate the idea.
Hume says this is an idea without an impression, but it is so ‘singular’ he dismisses it.


All ideas (especially abstract ones), are naturally faint and obscure.
All impressions (whether inward or outward) are strong and vivid
When we use a philosophical term we need to ask “from what impression is that supposed to have derived?
If you cannot find the corresponding impression then the idea is meaningless
By tracing the roots of our ideas, it is easier to analyse whether they are meaningful or not.



Some ideas are more vivid than impressions
Hume argues that our ideas are derived from inward and outward impressions, we distinguish between impressions and ideas by the force and vivacity - for instance a dream is a form of recollected ideas that can be distinguished from a real experience because of the way that dreams feel.

This view directly contrasts with Descartes suggestion that there are “no conclusive signs” in the way the experience is felt that can distinguish dreams from reality.

More generally it might be felt that sometimes the memory of an event can be just as vivid. If not more vivid than the actual event.

For instance, if I lose my keys I might retrace my steps in thought. The actual event of me losing my keys was not as vivid or forceful as I absent mindedly left my keys on the chair. The recollection however vividly recalls where they are.

Not everyone thinks experientially:

Hume implies that our thinking involves re-experiencing or conjuring up images, tastes, smells and feels. Although it is possible to think ‘experientially’ it is not necessary.

For instance, on hearing the sentence “John walked the dog”, one person might grasp this by experiencing the occurrence in their head of John walking the dog, but another might have no such accompanying mental goings on. Still, they both understand the sentence.



Critics say that Hume is making ‘thought’ too subjective. By that they mean that Hume is making ideas peculiar to the person who has them.

For instance, Daniel has an idea of an apple and Katie has an idea of an apple. If the idea of the apple for Daniel and the idea of an apple for Katie relate to their own personal impressions of apples, then ‘apple’ means different things to both of them.

Perhaps Daniel has only ever experienced sweet, red apples and Katie has only ever experienced green, rotting apples - their ideas of apples would be very different (although in real life, many would criticise this as being too extreme)


Ideas that go beyond experience:

Hume thinks our ideas derive from impressions and that just because of this any ideas that are not grounded in experience are suspect.

His theory is used as a way of challenging philosophical talk that goes beyond our experience.

Some, however feel that they can understand words or idea that go beyond experience such as ‘God’, ‘Infinity’ or ‘Nothingness’.

The missing shade of blue
Hume admits that we can have ideas about things we haven’t experienced, by allowing that a person who has experienced various shades of blue can have the idea of a shade of blue that they have never experienced.
(Hume says this example is too insignificant to worry about)
Some people argue that it IS significant, since anything that lays on a scale of continuum - we can have an idea of without an impression e.g. tones or temperature


As Hume wants to limit our ideas to experience he rules out understanding what lies beyond experience. This has serious implications for religion because many religious thinkers have dedicated their lives to understanding what lies beyond experience.

In the 20th century, A.J Ayer applied Hume’s ideas and drew the conclusion that religion was “the product of nonsense”. If religion was about anything at all, it was a reflection of human feelings.

This psychological theory of religion has been very influential but most religious people insist that their ideas are not about themselves rather about the transcendental.


Relations between ideas:

Hume thinks that our ideas are caused by impressions, but this accountcannot make sense of the way we construct relations between ideas. For instance, when we think we use terms like ‘either’, ‘or’, ‘if’, ‘then’, ‘and’ without which we could not think in the same way that we do. However, there is no impression which corresponds to any of these ideas. As such, these relation words are not derived from experience. Perhaps Hume has overestimated how much we derive from experience.

Is the mind more structured?

Similarly, we could argue that Hume has underestimated the extent to which our experiences are organised by pre-determined categories.

Kant argued that the categories of space, time and causation are part of the structure of the way we think rather than being derived from experience.

A nice analogy would be to think of an application form where everyone fills in the boxes with different experiences but the form pre-determines the kind of experiences that you are reporting.

In the same way the mind provides a framework. Hume suggests that there is no underlying structure to our thinking, but perhaps we play a more active role in our experiences than Hume gives us credit for.

Due to some of the things mentioned above - Hume’s claim that ideas derive from impressions seems to have quite a few major flaws.

However, perhaps Hume just over-estimated the amount of ideas that come solely from our experiences. So experiences do show themselves clearly within ideas, so Hume is making a valuable observation but it isn’t really that simple - there are many things which play an important role in shaping and forming our ideas.