Again stop with the self contradictions. They do or they don't, yes / no.

No worming in and out of speculative realms to qualify a yes and then a no.

Lack of evidence is not proof and lack of proof is not evidence. Therefore, the existence of aliens having not been proven true, demanding a yes or no answer creates a false dichotomy; forcing one into the realm of speculative conjecture. Until such time that, whatever we might classify as, 'space aliens,' are conclusively proven to exist, such existence remains a fractional value between true (1) and false (0).

In an infinite context, without dimension, it can not be proven conclusively that aliens do not exist; as such existence might always be proven tomorrow. Therefore, it must be deduced that in fact aliens do exist.

However, before you get all excited about the impending arrival of E.Ts. parent's. Our own existence, and therefore that of said alien parents, is highly debatable. Best explained by Douglas Adams in "The Hitch Hiker's Guide to the Galaxy"

"

Population [The Universe]

---------------------

None. Although you might see people from time to time, they are most likely products of your imagination. Simple mathematics tells us that the population of the Universe must be zero. Why? Well given that the volume of the universe is infinite there must be an infinite number of worlds. But not all of them are populated; therefore only a finite number are. Any finite number divided by infinity is as close to zero as makes no odds, therefore we can round the average population of the Universe to zero, and so the total population must be zero.

"

Q.E.D. I trust this clarifies things for you.