Things always act, or nearly always, in the same way. We know that the earth moves round the sun, oxygen exists, plants grow under the right conditions and we need to eat to stay alive. Our scientific enterprises are founded on the basic notion of order and regularity in the world. The argument from design can either begin with the whole of nature or part of it. However, there are a number of issues to be dealt with here.
Evolution is a self-contained process.
We merely exist today because the right conditions for our existence came about in the past. However, these conditions were not necessarily created in order for us to exist. In the end though the design argument flounders in the same way the cosmological argument does.