I pose to you the first a man complex and delicate, and to contrast a robot just as complex and delicate. What is the difference but materials of construction, the robot bears concentrated elements and alloys, while the man is a complex ecosystem of symbiotic processes. But is this difference sufficient to make one inferior to the other and thus not constitute constitution, I propose not.
Before you stands a man and a computer with the most identical an AI could be to a true man. Now would you deny the computer's status as a intelligent being capable of thought? Would you deny the computer the right to make its own decisions? Would you deny its capacity to be destroyed?
Now to return to a core concept that seems to permeate most games and is the crux of my most recent concern. Constitution; the state of being in the most ideal state for your defined being. A check box for if you have biological functions working, as is characterized in many games. As such we should adjust our view point to accommodate a truly precise definition.
Constitution is the strength of ones ability to maintain healthy function. For the future of the system proposed I advise we look to the causes of good health that can be be targeted or disrupted to cause harm. Immediately the circulatory system comes to mind, as it is the pathways energy and resources flow through a biological body. An electrical body shares similar pathways that serve to supply energy called wiring. Secondly their are the currents that flow through the nervous system which is near identical in a mechanical man, only major difference is their medium. With just these few examples you can see a recurring trend, and that trend is our initial application was incorrect.
In service of the correcting the error made from inception I propose below a new system to define constitution in a more accurate format.
All traits assume all effect have no innate impact on the subject, and thus provide exceptions to that rule.
Circulatory System (type): A system of pathways utilized to transfer energy and resources through out the body for uses by independent systems. Circulatory systems are split in 3 major groups; Fluid, Current, and Ethereal. Fluid is the type most common among biological creatures as it allows transference of several different resources efficiently. Current is the second most common found in the form of wiring and enchanting inlays. Ethereal is the final category providing flow with out material means to direct it, commonly found in beings where their body is their soul or their is a central magical seal allowing the whole thing to work.
A circulatory system comes with a few major drawbacks. It is generally meant to provide long term care to something that has a consistent drain of resources. As such any obstruction to flow of resources can quickly result in damage, loss of use of systems, or even consistent bleed off until the damage is repaired.
Information Structure: A system of pathways utilized to issue commands and transmit information to different portions of a body. This most commonly is a solid channels for electrical current. Any interruption to the system most often results in loss of control of any process past the interruption.
Constitution is broken into few separate bases.
Biological (Element Base) Constitution: Most life on planet earth is biological (carbon). The current definition of constitution assumes this as the default state. Any function in D&D, pathfinder, and other similar system works as written for these beings. Biological constitution requires constant supply of energy(usually Calories) and resources(all the extra material from eating and drinking and breathing). If base is not carbon many chemical based effect will have alternate effects. Biological have
Eldritch Constitution: This represents many constructs and a few other exceptions. They are often immune to many things that would harm biological creatures and physical damage rarely limits them unless they have a fluid circulatory system which is uncommon. Positive and negative energy have no effect, but antimagic areas and any effect that disrupts magic effects them. They can be healed with anything that repairs damage to objects.
Electronic Constitution: Most robots fall into this category. The major traits are anything that does electricity damage deals 50% more damage as the delicate systems get overloaded. They can be healed with anything that repairs damage to objects. Positive and negative energy have no effect, but areas that negate laws of physics and any effect that disrupts electronics effects them. They can be healed with anything that repairs damage to objects.
Necrotic Constitution: This represents many undead and a few other exceptions. They are often immune to many things that would harm biological creatures and physical damage rarely limits them unless they have a fluid circulatory system which is uncommon. Positive and negative energy reverse effects.