Key Arguments

• Locke opens by noting 'some are clear and others obscure; some distinct and others confused', introducing two cross‑cutting distinctions applied to ideas.
• He explains clarity of simple ideas by analogy with vision: just as an object is obscure when not in sufficient light to disclose its figure and colours, a simple idea is clear when presented as the object did or might in a 'well-ordered sensation or perception', and obscure insofar as it is faded or inaccurately retained in memory.
• Complex ideas are clear when the simple ideas composing them are themselves clear and when 'the number and order' of those component ideas is determinate and certain.
• He defines a distinct idea as one wherein 'the mind perceives a difference from all other', and a confused idea as one that 'is not sufficiently distinguishable from another, from which it ought to be different'.

Source Quotes

I must nevertheless, crave leave to offer some few other considerations concerning them. The first is, that some are clear and others obscure; some distinct and others confused. 2.

Clear and obscure explained by sight. The perception of the mind being most aptly explained by words relating to the sight, we shall best understand what is meant by clear and obscure in our ideas, by reflecting on what we call clear and obscure in the objects of sight. Light being that which discovers to us visible objects, we give the name of obscure to that which is not placed in a light sufficient to discover minutely to us the figure and colours which are observable in it, and which, in a better light, would be discernible.

Light being that which discovers to us visible objects, we give the name of obscure to that which is not placed in a light sufficient to discover minutely to us the figure and colours which are observable in it, and which, in a better light, would be discernible. In like manner, our simple ideas are clear, when they are such as the objects themselves from whence they were taken did or might, in a well-ordered sensation or perception, present them. Whilst the memory retains them thus, and can produce them to the mind whenever it has occasion to consider them, they are clear ideas.

In like manner, our simple ideas are clear, when they are such as the objects themselves from whence they were taken did or might, in a well-ordered sensation or perception, present them. Whilst the memory retains them thus, and can produce them to the mind whenever it has occasion to consider them, they are clear ideas. So far as they either want anything of the original exactness, or have lost any of their first freshness, and are, as it were, faded or tarnished by time, so far are they obscure.

So far as they either want anything of the original exactness, or have lost any of their first freshness, and are, as it were, faded or tarnished by time, so far are they obscure. Complex ideas, as they are made up of simple ones, so they are clear, when the ideas that go to their composition are clear, and the number and order of those simple ideas that are the ingredients of any complex one is determinate and certain. 3.

Distinct and confused, what. As a clear idea is that whereof the mind has such a full and evident perception, as it does receive from an outward object operating duly on a well-disposed organ, so a distinct idea is that wherein the mind perceives a difference from all other; and a confused idea is such an one as is not sufficiently distinguishable from another, from which it ought to be different. 5.

Key Concepts

• The first is, that some are clear and others obscure; some distinct and others confused.
• we shall best understand what is meant by clear and obscure in our ideas, by reflecting on what we call clear and obscure in the objects of sight.
• our simple ideas are clear, when they are such as the objects themselves from whence they were taken did or might, in a well-ordered sensation or perception, present them.
• Whilst the memory retains them thus, and can produce them to the mind whenever it has occasion to consider them, they are clear ideas.
• Complex ideas, as they are made up of simple ones, so they are clear, when the ideas that go to their composition are clear, and the number and order of those simple ideas that are the ingredients of any complex one is determinate and certain.
• a distinct idea is that wherein the mind perceives a difference from all other; and a confused idea is such an one as is not sufficiently distinguishable from another, from which it ought to be different.

Context

Book II, Chapter XXIX, §§1–4, where Locke introduces and preliminarily defines the pairs 'clear/obscure' and 'distinct/confused' using analogies with sight and memory.