Scientists have come to the conclusion that humans are biochemical machines. As a species, we form a network of machines. As a planet, we form an even bigger network... etc... with the biggest network of them all being the universe itself.
Yes, the universe itself appears to be nothing but a fully deterministic network of machines... like the Internet... where everything that happens at time T is completely determined by what happened at time T - 1... and everything that happens at time T - 1 is completely determined by what happened at time T - 2... etc.
This leaves little room for "free will" as it is traditionally defined. And without "free will", what does it mean to be "conscious"? What does it mean to be an individual? What does it mean to be "you" if every decision, every emotion and every thought you ever had is just the consequence of a long chain of events that goes back to the beginning of time (if there's any beginning at all)?
So, basically, the reason scientists and philosophers say "consciousness" is an illusion, is because our thoughts and feelings don't seem to be able to have any impact on changing the world around us. "We" appear to be mere passengers in our own body, under the illusion that we are its drivers.
Here's how Austin philosophy professor David Sosa explains it :
In a way, in our contemporary world view, it's easy to think that
science has come to take the place of God. But some philosophical
problems remain as troubling as ever. Take the problem of free will.
This problem has been around for a long time, since before Aristotle
in 350 B.C. St. Augustine, St. Thomas Aquinas, these guys all worried
about how we can be free if God already knows in advance everything
you're gonna do. Nowadays we know that the world operates according to
some fundamental physical laws, and these laws govern the behavior of
every object in the world. Now, these laws, because they're so
trustworthy, they enable incredible technological achievements. But
look at yourself. We're just physical systems too, right? We're just
complex arrangements of carbon molecules. We're mostly water, and our
behavior isn't gonna be an exception to these basic physical laws. So
it starts to look like whether its God setting things up in advance
and knowing everything you're gonna do or whether it's these basic
physical laws governing everything, there's not a lot of room left for
So now you might be tempted to just ignore the question, ignore the
mystery of free will. Say "Oh, well, it's just an historical anecdote.
It's sophomoric. It's a question with no answer. Just forget about
it." But the question keeps staring you right in the face. You think
about individuality for example, who you are. Who you are is mostly a
matter of the free choices that you make. Or take responsibility. You
can only be held responsible, you can only be found guilty, or you can
only be admired or respected for things you did of your own free will.
So the question keeps coming back, and we don't really have a solution
to it. It starts to look like all our decisions are really just a
Think about how it happens. There's some electrical activity in your
brain. Your neurons fire. They send a signal down into your nervous
system. It passes along down into your muscle fibers. They twitch. You
might, say, reach out your arm. It looks like it's a free action on
your part, but every one of those - every part of that process is
actually governed by physical law, chemical laws, electrical laws, and
So now it just looks like the big bang set up the initial conditions,
and the whole rest of human history, and even before, is really just
the playing out of subatomic particles according to these basic
fundamental physical laws. We think we're special. We think we have
some kind of special dignity, but that now comes under threat. I mean,
that's really challenged by this picture.
So you might be saying, "Well, wait a minute. What about quantum
mechanics? I know enough contemporary physical theory to know it's not
really like that. It's really a probabilistic theory. There's room.
It's loose. It's not deterministic." And that's going to enable us to
understand free will. But if you look at the details, it's not really
going to help because what happens is you have some very small quantum
particles, and their behavior is apparently a bit random. They swerve.
Their behavior is absurd in the sense that its unpredictable and we
can't understand it based on anything that came before. It just does
something out of the blue, according to a probabilistic framework. But
is that going to help with freedom? I mean, should our freedom be just
a matter of probabilities, just some random swerving in a chaotic
system? That starts to seem like it's worse. I'd rather be a gear in a
big deterministic physical machine than just some random swerving.
So we can't just ignore the problem. We have to find room in our
contemporary world view for persons with all that that entails; not
just bodies, but persons. And that means trying to solve the problem
of freedom, finding room for choice and responsibility, and trying to
So what IS consciousness, then? What's the point of being passengers in our own body? How CAN we make sense of consciousness in a deterministic universe? Well, in the model for consciousness that I personally apply, consciousness is merely a product of complexity and connectivity. In this model, consciousness is little more of a side-effect to that complexity and connectivity.
A direct consequence of this, however, would be that EVERYTHING in the universe is conscious, albeit to varying degrees and structured in many layers of consciousness. I used to refer to this as a Matryoshka model of consciousness, but it's really just nothing but Animism... or Pantheism... which are just different perspectives on the same fundamental concepts of consciousness. I elaborate on this in greater detail in my article The Atheistic approach to God… or how to bridge the gap between Atheists and Theists.
Note that I'm not arguing that this model MUST be true and is the only acceptable model of consciousness. It's just A model and THE model that I personally find making more sense than any other models I've looked into. However, I by no means want to even remotely give the impression that this model is to be considered a 100% accurate representation of "consciousness". While scientists are pretty conclusive on the universe being deterministic (this, I believe, is no longer a matter of opinion), the very nature of "consciousness" still remains a matter of speculation.
Some additional sources on the illusionary nature of free will :