A proposition may indeed be true even if we are unaware of its truth. This leads us to an important question in epistemology: How do we come to know what we know? Philosophers have identified six primary sources of knowledge, each of which contributes uniquely to our understanding of the world. 

Knowledge Through Sense Experience

Our senses are key gateways to knowledge about the external world. Through seeing, hearing, touching, smelling, and tasting, we learn about the world around us: the shape, color, texture, sound, smell, and taste of things.

For instance, we know that there is a table in front of us because we see it or touch it. These sensory inputs allow us to form judgments about the world. However, there are occasions where sensory perception can mislead us — for example, mistaking a rope for a snake in dim light. This is called a perceptual error.

It’s important to note that when such errors occur, the problem lies not in the senses themselves but in the judgment we make based on sensory input. When errors arise due to incomplete information, more sensory experience can help correct our understanding. For instance, walking closer to the object and examining it more closely will reveal whether it is a snake or a rope.

In addition to external senses, we also have internal senses. These give us awareness of our inner states, such as emotions, feelings, moods, thoughts, and bodily sensations. For example:

• “I have a headache.”
• “I feel sad.”
• “I am thinking about my vacation.”

These inner experiences serve as direct evidence for statements we make about ourselves. The fact that one feels a headache or sadness is sufficient proof that this state exists.

A useful distinction here is between occurrent states (states that are happening right now, like feeling pain) and dispositional states (states that express a tendency, such as being irritable or having a talent that is not currently active). Understanding this distinction helps explain the types of knowledge we gather from internal awareness.