Before computers were widespread we saw the world as divided mainly into three kinds of things: inanimate objects, living beings and rational beings and rational beings were a subclass of living beings.
Mankind was superior because it was, in most Occidental intelectual's eyes, the only rational creature on the planet. Rationality was associated with a developed mind, a developed awareness. To be rational was to be the supreme living creature.
Then computers came up, now a measly calculator machine can do much more accurate calculations than most "supreme" human beings. Does that mean it has more ability for doing calculations than most human beings? Is it a cognitive ability? Does it make the calculator "rational"? Does it make it more rational in doing calculations than most men? Does it make it aware?
Of course, a calculator does not seem very threatening, it is just lying there, waiting for us to press the buttons. But in the space of just a few decades the transistor has allowed us to build ever more complex intelligent stuff. Computers that can play chess and learn from their bad moves, that can order long lists of data finding out patterns and correlations, that are improving their abilities on our natural language, whether it is reading, listening or translating our natural languages. In other words, they are becoming more and more like us!
So, if something behaves like us, shouldn't we say it is because it has the same abilities that we have? If a machine is able to behave just like a human, passing the "Turing test", on what grounds could we say that we have something - intelligence, awareness, etc - that she has not? Wouldn't that be unjustified discrimination?
Well, the problem with attributing consciousness to calculators, computers and so on goes back to our first unwarranted attribution. It was attractive to us to see man on top of the evolution ladder. Since we are not prettier, faster, more emotional, or have more senses than all the other animals, we focused on what we had different: we were intelligent. And, somehow, the intelligence was to be considered more important than feeling for instance, or perception, or the gregarious qualities of compassion, love and fidelity.
But, of course, we have nothing in our mental life that indicates that consciousness is necessarily connected with rationality. By the contrary, our mental life shows that many of the things we feel are not rationalizable or even describable (like what we feel when we listen to a beautiful music. Can you make a rule for creating beautiful music? Can we describe the algorithms that make some pieces sublime while others are not? Can we describe to others, or even to ourselves what we feel when we listen to Mozart or Bach? Of course we can't. There are many things we feel that do not fit in our rational language. Conversely, when we do a calculation, like 2+2 or 3^3, we get a result, we see the result, we can even analyze each of the steps that lead to the result, but process itself of getting to each of the images - the image of the end result - "4" and "9" - or the images of each of the steps (adding a set of two dots to another set of two dots, consider a superset that includes the two smaller sets, etc), all these congnitive processes go on "in the dark". We have absolutely no conscious control over them. It's like wanting to move an arm. We have the urge to move the arm and, somehow, it does move. If we have a neural disorder perhaps it will stop from moving, but our awareness, our will to move the arm, our perception of what it is to be like wanting to move the arm and giving the commands(?) for it to move, may be unchanged. In other words, we have absolutely no conscious perception of the mechanics that lead us to actually moving the arm. We want it to move, we feel it moving, we see it moving. But we are not aware of what, in our brain or our body makes it move.
In the same way we are not aware of the mechanisms in our brains that makes us able to think, to make calculations, to arrive at "accepted", rational results. We simply do have that ability. So, consciousness is not particularly connected with rationality. Rationality is a particular ability of human beings, developed by the species, but that no human being really feels. We just use it, as we use our arms.
So, from a first person perspective, we have no reason to associate intelligence with consciousness. Computers might just be like some parts of our brain: blindly working out the results, automatically, without any kind of association to a conscious experience. Just as our brain provides the numbers and pictures of processes, so the machine may be providing the same kind of results in the some kind of blind way.
Of course, other things may be happening too. Perhaps there is consciousness associated with summing 2+2 in our head, or in moving an arm, but they are running parallel to the consciousness of the I. That is, perhaps there is a cognitive process that creates and maintains a concept of the I, which is associated with consciousness, my consciousness, of which I can talk about, whereas there are many other congnitive processes, running in parallel, and associated with conscious experiences, but of which I am not aware. of course, that is possible. It is also possible that a martian is actually having lots of experiences in my brain, but, of course, I'm just not aware of it. Everything is possible considering that I am not aware of it. I cannot deny it or prove it. the question should be: do I have any reason to believe such stuff?