To be free in the ordinary sense is, at base, a matter of being able to do what one wants: I am thirsty. I know there is something to drink in the refrigerator, so I open the refrigerator. This is a freely willed act, as opposed to my being forced to do the same by a man with a gun, or to my being unable to do the same because I am tied down to a chair.
A "want", of course, is realized by a state of the brain. The human nervous system has osmoreceptors that detect changes in the osmotic pressure of the blood and other fluids. When they detect decreased volume or increased concentration of salt, they cause us to feel thirsty. The mediators of wants are biophysical. (Or to put it as I've put it before, robots -- at least, robots of sufficient cognitive complexity -- could have wants. And if being free in the ordinary sense is a matter of being able to do what one wants, robots could be just as free as us).
But there is another sense of 'freedom' that comes up, for example, in the famous Ariyapariyesana Sutta of the Buddhist Pali Canon. Here we are told that "wants" or "desires" themselves are bonds! How could this be if freedom is, at base, being able to do what one wants?
Here is the relevant passage from the Sutta:
Monks, there are these five strings of sensuality. Which five? Forms cognizable via the eye — agreeable, pleasing, charming, endearing, fostering desire, enticing. Sounds cognizable via the ear — agreeable, pleasing, charming, endearing, fostering desire, enticing. Aromas cognizable via the nose — agreeable, pleasing, charming, endearing, fostering desire, enticing. Tastes cognizable via the tongue — agreeable, pleasing, charming, endearing, fostering desire, enticing. Tactile sensations cognizable via the body — agreeable, pleasing, charming, endearing, fostering desire, enticing. These are the five strings of sensuality.
And any brahmans or contemplatives tied to these five strings of sensuality — infatuated with them, having totally fallen for them, consuming them without seeing their drawbacks or discerning the escape from them — should be known as having met with misfortune, having met with ruin; Mara can do with them as he will. Just as if a wild deer were to lie bound on a heap of snares: it should be known as having met with misfortune, having met with ruin; the hunter can do with it as he will. When the hunter comes, it won't get away as it would like. In the same way, any brahmans or contemplatives tied to these five strings of sensuality — infatuated with them, having totally fallen for them, consuming them without seeing their drawbacks or discerning the escape from them — should be known as having met with misfortune, having met with ruin; Mara can do with them as he will.
The pleasures we get from the senses are like strings that bind us; desires based upon them can tie us down like a deer before the hunter.
But what sort of freedom is this? Surely we are free -- at least, free in the ordinary, everyday sense -- just insofar as we can grasp at whatever desires suit our fancy. Far from binding us in a heap of snares, this pursuit of pleasure is what gives our life whatever expansiveness it has.
This is the kind of Enlightenment freedom alluded to in the US Declaration of Independence: that we possess "certain unalienable rights, that among these are life, liberty and the pursuit of happiness." Our freedom comes not only in liberty from interference, but also in liberty to pursue happiness where we find it. If we want to indulge ourselves by looking at drip paintings, playing the violin or eating gourmet meals, then it is in their pursuit that we find freedom.
But then, wherein lies the snare?
Consider this phrase from the Sutta: "... without seeing their drawbacks". Is it really true that every pursuit of happiness leads to its attainment? Don't many lead to unhappiness?
It's not unusual for the pursuit of pleasure to lapse into dull routine or worse, obsession or compulsion. One buys the object, sees the show, climbs the mountain, drinks the wine, kisses the pretty face, not because it is pleasurable but because it ticks some box that says, "Not done yet." It fits into an empty space in the collector's book. And while filling that space may provide some modest frisson, the feeling cannot last.
Nor are such pursuits to one's benefit: being tied to sensual delights without seeing their drawbacks is a route to disappointment. Although all desires aim at pleasure, many misfire along the way, bringing unhappiness. Often we know this to be the case, we know we do ourselves no good by acting upon the desire, yet we indulge nonetheless. This is a kind of fetter.
A desire that brings unhappiness when acted upon is not the kind of desire that brings true freedom. A desire that brings unhappiness is, in that sense, a kind of fetter or bond that reduces one's true freedom even while providing ordinary freedom.
The "pursuit of happiness" is its own freedom just so long as that pursuit is well-aimed. The obsessive collector who drains his account in the purchase of pretty things, the lothario, the thief, not to mention the alcoholic or addict, all to one extent or another do what they do freely, in the ordinary sense of the word. (The addict or true obsessive less so, since mental illness is its own bind). But they rarely get the happiness they seek. To that extent, they are not truly free.