Why can’t we see in the dark like cats and owls?

In order to see, the eye must receive light; and darkness is the absence of light. Most of the objects we see around us are visible by reflected light — reflected sunlight or reflected artificial light. Since darkness is the absence of light, there is no light in the darkness to be reflected from chairs, tables, or people to our eyes, and therefore we can not see these objects.
Cats and owls can see in the dark because they have special kinds of eyes. It is true that cats and owls can see better in partial darkness than we can, because the pupils of their eyes can open wider and receive more light than our eyes can. You have probably noticed that it is difficult to see objects inside a house when you have just come in from the bright sunlight. After you have been in the house a little while, your eyes adapt themselves to the dimmer light, and you can see perfectly well. It is true, too, that our eyes become somewhat accustomed to the dark after a while. If you go out of the lighted house on a dark night, you find that after ten or fifteen minutes you can see much better than when you first left the house.

Additional reading:
Eye (Wikipedia)

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