If you put a flower, next to a painting of a flower, would the painting be more beautiful because it has been intentionally drawn? A still life is seen as having more aesthetic value than a flower in a vase, although our eyes see no difference between the two.

It isn't quite right that we see no difference between a flower or a bunch of flowers and a standard still life. For example, we see paintings as largely flat, and we take notice of their painted surfaces. This distinguishes our experience of them from our experience of flowers. More importantly, we typically value the two sorts of objects in different ways. A still life might be valued because of its beauty but also because of the skill of the painter, its capacity to express and evoke emotion, what it symbolizes, and/or the perspective on the world it manifests. That is, we value paintings as works of art, not as mere aesthetic objects. (Beauty is not our only concern when we look at paintings of flowers.) While we sometimes value bouquets of flowers for what they express, the art of flower arrangement does not seem to have the rich capacity for expression and meaning that painting does. The same is true for mere bunches of flowers.

So the answer to your original question is no. Merely being intentionally drawn does not make something beautiful (for one thing, there are ugly still lifes), nor need successful still life involve a degree of beauty that cannot be found in a single flower or arrangement of flowers. But there are reasons to think that there are values to be found in great works of visual art that are not to be found in a flower in a vase.

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