[Since the subject of this paper is "wireheading", readers may do well to ensure that they are familiar with what this term means. An eye-opening introduction to the subject is available on paradise-engineering.com.]
I shall attempt here to address an issue which would not overly tax philosophers of an intuitionist bent, and which does not appear to occur to many others. The subject is wireheading, and issue in particular is whether or not it would be useful in the world as it is. Let me show my disagreement with the intuitionists fully: granted, the idea of wireheading is initially repugnant; granted, wireheading is "invasive"; and granted it seems contrary to our normal sense of "dignity"; however, despite such value-laden commentary, the question - for non-intuitionists like myself - remains open: is it a good thing? If wireheading became more common, would this tend to lead to a better or worse state of affairs than we have now, or than that we would otherwise be led to?
The standard by which I shall attempt to measure the value of wireheading is that of the hedonistic utilitarians, but it bears mentioning that this is not the only standard of ethics which has something to say about wireheading... any standard which cares at all for the happiness or misery of others must have something potentially positive to say about it. The greater understanding of the mind that research on this subject would lead to, may have significant benefits which are appealing to preference-satisfaction or desire-fulfilment value-theorists, or those systems which value knowledge and understanding for their own sakes.
It would not even be absurd to advocate wireheading from a position asserting an eco-centric theory of value: when one notes the harms done today by the multitudes of people consuming vast quantities of resources, and producing large amounts of pollution in the process, in actions for which any possible justification (if any even be offered) would be most implausible if it were not reducible to the desire, inclination, or happiness of the agent or agents, the need for a lower cost alternative becomes obvious. So let us stop trashing the planet in an attempt to achieve a goal by a means (i.e. material consumption) which simply cannot possibly succeed, and look to more promising routes.
As the experiments on mentally ill persons have shown, wireheading has a most remarkable potential for helping the sick - not just clinically "depressed" persons, but also those suffering from schizophrenia and other disorders. So let the opponents of wireheading be quite clear in their minds about what they are doing: if they decide that, all things considered, we should not allow wireheading, they have sacrificed the interests of at least these mentally ill persons for some "greater good". And let them therefore be ever so clear about what this greater good is, and how standing back and declining to prevent the misery and agony of the mentally ill achieves it.
The utility of wireheading is not obviously limited to those suffering from currently recognized mental disorders. It is potentially useful, and - initial discomfort with the idea aside - potentially desirable, to anybody. I do not here mean only hedonists, of the sort who take illicit substances in a crude and (in comparison to wireheading) somewhat ineffective, if not self-defeating attempt to increase their levels of happiness: given the strong relationship between pleasure, psychological reward, and motivation, it may well be that wireheads could be more active and more productive than their non-wireheaded ancestors (and contemporaries). Therefore anyone who would do anything might find their goals better achieved with wireheading. In short, even those who deny that happiness has intrinsic value may very well find that it is instrumentally valuable.
Wireheading has a significant feature that the pioneers may find both attractive and comforting: flexibility. It can be set up in such a way as to be controlled by the wirehead themselves. Assuming that various regions of the brain are wired, it ought to be possible for the wirehead to choose the mode of pleasure received. Calm satisfaction? Excitement? Erotic? And not only can they call the tune, they will presumably also have precise control over the volume.  Including, at their option, zero. Electrodes can even be withdrawn, or the electrical supply to them disconnected. Given this, the perceived "cost" of being wireheaded may be lower than otherwise expected. So it seems that in any future utilitarian, libertarian or desire-fulfilment-oriented society, where wireheading will be one available option, the necessary surgery may well prove popular.
In fact, competition for the opportunity to be wireheaded may well become fierce. If such a situation arises, the prima facie correct position is that priority should be given to the most mentally ill, or others who must endure great suffering, since they have the most to gain. But this is not to say that wireheading will not arouse the most heated opposition. All manner of intuitionists, religious types, and busy-bodies can be relied upon to pronounce it "unnatural" and "improper" and perhaps oppose it quite vigorously. Some will no doubt claim their opposition to be on "moral grounds", though it may be quite unclear what these grounds are. Such people would do well to heed Bentham's advice for such situations.
Wireheading requires surgery. This presumably makes it impractical for many of the painient beings on the planet: the wild animals. It is therefore vital that any investigation into wireheading be prevented from distracting attention from other forms of paradise-engineering which can be applied more widely. Once these other techniques have been perfected, they will perhaps be applied to humans and any other domesticated animals who may have previously benefited from wireheading - and the idea of sticking wires in our brains will again be regarded as crude. The role of wireheading may then be a limited one in the greater scheme of paradise-engineering.
Wireheading is in many ways a young subject with little background material - of which very little is easily available. It is therefore one which is full of highly relevant but unanswered questions. I will list some of them here, and hope that the answers are forthcoming.
What are the effects (presumably variable depending on electrode placement) of wireheading - and happiness generally - on "normal" people? In particular, is it addictive? Does it lead to them finding some activities more or less rewarding or motivating (which may be a good or bad effect, depending on whether these other activities ought be done)? Does wireheading make psychological hedonism falsifiable (i.e. verifiable)? (And, if so, is it true or false?) Does it have any effect on the potential for critical reasoning? And on the estimation of probabilities - for example does it make one overly optimistic? Since it can make people relatively immune to suffering, is it not potentially dangerous in that it could eliminate all grounds for sympathetic action? Or could empathy be in fact increased? What are the risks involved with increased knowledge of the subject - will evildoers use the technology to stimulate pain rather than pleasure centres? Could we inadvertently thereby create not a heaven but a hell? Possibly more seriously, is it possible to wirehead someone in such a way that the pleasure is so intense as to be incapacitating? If so, how can one prevent this "abuse-potential" being realised (for as long as functionality is necessary, at least)? Will there be back-alley wireheading units, whose input is a fully-functional member of society, and whose output is a blissed-out junkie no longer any good to anyone else?
I am afraid that the answers to these questions are non-obvious, though they may become clearer with further research. The value of wireheading, while the potential magnitude is assuredly massive, the sign of it - i.e. whether it is positively or negatively valuable - is far from certain. The prima facie case being in favour, I would suggest that further research should be taken to clear up some of the problems. Until then any estimation of its value is wild speculation.
On any plausible (or merely popular) account of ethics, wireheading must be a very serious issue - its impact on the world might be remarkably good, or terribly harmful. The general silence, broken only by a very few, is therefore highly suspect - it is as if the issue is being decided in the absence of fair consideration. But given the general lack of interest in philosophical matters, and moral philosophy in particular, this silence is really quite the par for the course.
1. It has occurred to me that something like a modern-day film could be used - only, you do not merely see the sights and hear the sounds, but you taste the flavours, smell the scents, and feel everything - including the fear, excitement, lust, or whatever at the prescribed points in the presentation. However, I am quite confident that this represents a failure on the part of my imagination - the very idea of needing something to be happy (or scared, for horror show fans, or whatever) about is about to outlive its usefulness. Similarly, this idea of needing variation in experience is presumably a hangover from the observed need for variation in environmental stimulation, if the stimulus is not to become habituated. I am confident that we will in fact find that we can never be bored of being happy, nor discontent with being satisfied.
2. This from the IPML:
I feel in myself, (say you again) a disposition to detest such or such an action in a moral view; but this is not owing to any notions I have of its being a mischievous one to the community. I do not pretend to know whether it be a mischievous one or not: it may be not a mischievous one: it may be, for aught I know, an useful one.May it indeed, (say I) an useful one? but let me tell you then, that unless duty, and right and wrong, be just what you please to make them, if it really be not a mischievous one, and any body has a mind to do it, it is no duty of yours, but, on the contrary, it would be very wrong in you, to take upon you to prevent him: detest it within yourself as much as you please; that may be a very good reason (unless it be also a useful one) for your not doing it yourself: but if you go about, by word or deed, to do any thing to hinder him, or make him suffer for it, it is you, and not he, that have done wrong: it is not your setting yourself to blame his conduct, or branding it with the name of vice, that will make him culpable, or you blameless. Therefore, if you can make yourself content that he shall be of one mind, and you of another, about that matter, and so continue, it is well: but if nothing will serve you, but that you and he must needs be of the same mind, I'll tell you what you have to do: it is for you to get the better of your antipathy, not for him to truckle to it.