To start off with, the writer, Mr. Vaknin, makes the flat statement that "In all works of science fiction, there are ten hidden assumptions regarding alien races." Well, no. For one thing, there are many works of science fiction that contain no reference to aliens at all. (I should know; I've written quite a few myself.) When science fiction isn't about aliens, and doesn't include aliens, there are no "hidden assumptions" about aliens. Right here we can see a logic flaw of the type that leads to the construction of large straw men so the critic can knock them down while crowing of his superior might. And sure enough, the straw starts piling up, and the critic bashes away at it...but y'know, those of us who actually know something about a) science fiction and b) how aliens are depicted in science fiction and c) why fiction is what it is and not something else, are not fooled into believing that the sack of straw is an actual science fiction writer or his/her work.
The easiest response to this is that the science fiction writer is not required to imagine and report on every possible "being" in the entire universe. Criticizing science fiction for not doing what it was never intended to do (explain everything, demonstrate everything, think of everything, imagine everything that someone thinks it should) is ridiculous. Science fiction, unlike for instance science, is first and foremost fiction: storytelling. If the writer also imparts some information about a science (or science in general), or speculates on the nature of planets in another solar system or what might be found there, fine and dandy, but the writer's first requirement--in writing any kind of fiction--is to tell a story. In genres considered "commercial" (among which is science fiction) that's the overriding requirement. So there goes the head of the straw man, hat off and the straw flying away
But--though perfectly true and universal--the easy response isn't the one that needs to be given here. When a perfect example of how not to critique a genre comes along, it deserves more careful and painstaking consideration. Let's start with the factual errors in Mr. Vaknin's claim, before going on to the literary bits. According to him, all science fiction works commit all ten errors. We've dealt already with one claim--since aliens aren't in all--but let's look at some of the others. Do all SF works that include aliens imagine those aliens as "anthropomorphic in body and psychology"? No. And it would not take much familiarity with modern science fiction to find numerous examples to the contrary (off the top of my head, Niven and Cherryh both wrote such aliens. So have many others. Do all such SF works use carbon-based life? No. Do all such SF works assume a similar genetic structure? No. So let's let the straw loose from the left forearm of the straw man.
Mr. Vaknin claims that "we" (suddenly he's talking about his readership, it looks like, and not science fiction writers--but he wavers back and forth) imagine aliens to have the same qualities in the same way that we think about living things on this planet--in addition to "anthropomorphic structure", communication and interaction, a physical being with a physical location, separateness from one another and the rest of the universe, means of transportation, will/intention, intelligence, complexity, an artificial/natural distinction, and similar social structures, including "Nazi"-like leadership. He hedges his claims occasionally, with qualifying terms like "most" and "the majority of" but he's still shoved the straw into some clothes and is beating it generously while proclaiming it's real. Is it true? Do "we" (his audience or science fiction writers) believe all this stuff about aliens? No. The evidence from science fiction is that "we" don't. The straw's all blown away now; leaving him whipping the air. Since Mr. Vaknin mentions science fiction movies, and appears unfamiliar with well-known, award-winning science fiction books that prove him wrong, I suspect that he may have watched a few science fiction movies but has read very few books.
Immediately after his attack on science fiction--in the same article--he tears into intelligent design (not something you find a lot of in science fiction) and SETI (which you do.) I'm not an apologist for intelligent design, but if you're going to attack it, at least do so with facts and logical rigor. Mr. Vaknin achieves neither. In both following rants, Mr.Vaknin shows the same propensity to build a straw man, then whale away at it, and the same inability to imagine that something he hasn't thought of might exist....(saying that no intelligent being would design the universe the way it is, after complaining that SF writers can't imagine anything unfamiliar is laying yourself wide open and letting all the straw out of the king's new clothes. If, as he said earlier, "our inability to imagine something, even in principle, is no proof that it cannot or does not exist"...then he just shot himself in the other foot. I prefer to base my opposition to intelligent design on sounder footing, pun intended.)
But back to science fiction and aliens. Mr. Vaknin would, apparently, like a science fiction work to show (all in one) a "being" that is not alive by any standard we can think of, that does not communicate or interact with anything or anyone, that has no physical reality or location, has no means of transportation, has no will or intention...etc. In other words, his favorite notion of what non-terrestrial beings might be.
I suggest that he try to write a salable story with one of these as either a character or the motivational shove for other characters. He might then learn something about fiction. Fiction is an art appreciated by one species that we know of: humans. Not all humans, but many, at some point in their lives, like stories. Stories are built, of necessity, out of the experience of those for whom they are told--other people. We know that dragonflies don't care about stories we tell. We know that our domestic animals, however interactive with us, don't want stories. We may tell stories about dragonflies, or dogs, or horses, or fairy princesses, or aliens--and we don't expect any of those to listen to the stories. The stories we tell are human stories, exploring, with more or less skill and imagination, what it is to be human.
When science fiction writers choose to include aliens in their works, they know perfectly well that they are imagining something they cannot know for sure...but they also know they are entertaining other humans. They do not make the mistake of thinking their aliens are "real"--as their readers are real. They do not make the mistake of thinking they have replaced the real universe with their own invented one, nor do they expect their readers to think that out in the wilds of space they might find the aliens and alien societies they make up. And the imagined aliens are there to serve a purpose in the story...not to educate readers about aliens. None of us knows what's out there. It might be anything. It's just about certain to include things we haven't thought of--but could just as easily include things we have thought of.
For the purpose of a story, a being is either scenery or character. If you have a nonliving, unmoving, nonlocalized, nonmaterial, noncommunicative, inactive and intention-less "something"....at best it's scenery. (Except that if your characters are human, how are they going to know it's even there? In which case it's not even scenery.) Fiction requires characters who do something. In order to be a character in fiction, an alien must interact with at least one other character, and the writer must be able to make its behavior understandable to the reader (or the reader gets bored and tosses the book, and the writer gets dumped by his/her publisher.) So a writer considering possible aliens for his/her science fiction book may imagine the nonliving, unmoving, nonlocalized, etc., possibility, but will also imagine the effect on his/her career if it's used...and will hunt around in imagination for something more suitable. (In the same way that a writer will avoid those aspects of everyday real life that just don't do well in fiction...the bored housewife in the kitchen for thirty pages, musing on her boredom; the bickering couple who never achieve resolution and aren't that interesting, and many others.) Those who want to read only about themselves are fewer than those who want to read something that goes beyond their own experience. Fiction has few rules, but "Don't bore the reader" is one of them.
Mr. Vaknin is not the first to mistake the distinction between fiction (as an art, as an occupation, as a diversion) and "real life" (though he's hot on the notion that real life isn't really there, it's all an illusion. I'll bet he doesn't feel that way when it's his toothache.) But the take-home lesson is, if you want to trash something, know your subject--get the facts right--construct a logical argument (minus any straw men on stage or in the audience.)
Ritual disclaimer: Yes, there are errors in some science fiction works. And no, science fiction writer have not (and cannot) get all the details of the distant universe right in their work. But I cannot at this moment think of one error made by "every" science fiction writer in every work.