1.  The Concept of a Right

        Many of the central issues that arise in this area involve the concept of a right.  So we need to ask what it means to say that something has a right.

        One thing that is surely true is this:

    If X has a right, then there are some ways of treating X that are at least prima facie wrong.

        But while it is a necessary condition of X's having a right is that there are some ways of treating X that are at least prima facie wrong, is this also a sufficient condition?  That is to say, is the fact that it is wrong to treat X in certain ways all that is needed to give X a right?

        Suppose, to consider a concrete case, that it would be wrong to destroy X.  Does that by itself mean that X has a right not to be destroyed?  It seems clear that it does not.  The reason is that there can be very different grounds for its being wrong to destroy X.  On the one hand, it may be wrong to destroy X because X belongs to someone.  Or it may be wrong to destroy X because of the consequences for individuals other than X.  Neither of these sorts of reasons would seem to give one grounds for attributing a right not to be destroyed to X.  If X is to have a right not to be destroyed, it must be that in destroying X one not merely does something wrong, but that one wrongs X, that one does wrong to X.  Moreover, at least in the case of natural rights - as contrasted with rights that arise, for example, by contracts - it seems that its being wrong to do something to X only reflects a right that X has if the ground of the action's being wrong is a matter of properties of X, rather than being a matter of X's relation to other things.

        Most philosophers would, I think, agree with the above. Nevertheless, this agreement notwithstanding, there are still substantial disagreements concerning the concept of a right.  Some philosophers, for example, hold that only moral agents can have rights - where a moral agent is something that can choose between alternative courses of action on the basis of moral considerations.  (A slightly different way of expressing the same view is in terms of the thesis that rights and duties go together, and that the only things that can have rights are things that can have duties.)  Other philosophers have contended that rights are connected with claims, and that only things that can claim rights can really have rights.  Still other philosophers have adopted a "social contract" approach to rights, and claim that rights arise out of agreements among individuals who view the mutual granting of rights as a desirable alternative to life in a state of nature - where life, in the words of Thomas Hobbes, is "nasty, brutish, and short".

        If any of the three views just mentioned is correct, then it will follow that many sentient beings, for example, do not have any rights, since many sentient beings (a) are not moral agents, (b) cannot advance claims that they have rights, and (c) are incapable of entering into any sort of contract.  The crucial moral question, however, is not simply whether one holds that such animals do not have any rights, but whether one also accepts, in addition, either (or both) of the following two claims:

(1)  None of the properties that the animals in question possess - such as a capacity to experience pain - are such as make it wrong to treat them in various ways;

(2)  Although some of the properties that the animals in question do possess - such as a capacity to experience pain - are such as make it wrong to treat them in various ways, such treatment is not as seriously wrong as it would be if they possessed the corresponding right.  (Thus the idea is that while treating cats in certain ways is wrong because it causes them to experience pain, it is not as wrong as it would be to inflict the same amount of pain upon individuals - such as humans - that have a right not to have pain inflicted upon them.

        Why are these theses crucial?  The answer is that if one does not accept either thesis (1) or thesis (2), and thus holds, for example, both that an animal's capacity to experience pain makes it prima facie wrong to inflict pain upon that animal, and, moreover, makes it just as wrong as it is in the case of a human, then it wouldn't appear to really matter from a moral point of view if one holds that, nevertheless, the animal does not have a right not to have pain inflicted upon it, since that will not make any difference with regard to the wrongness of the action in question.

2.  Some Central Issues

        Given the controversy concerning the term "right", it might well be better to formulate the central issues here without employing that term.  But that would make for considerably wordier formulations, and so what I shall do is to use the term "right", but interpret it in a minimal sort of way.  Specifically, to say that X has a right to A will be taken as asserting only:

        It would be at least prima facie wrong to deprive X of A, and the wrongness is intrinsic, rather than a matter of consequences; and, moreover, the wrongness is a matter of X's own properties, rather than of X's relations to other individuals.
 

        If we use the term "right" with that minimal sense, some of the central issues can be formulated as follows:

1.  Do any of the non-human animals that actually exist on earth have any rights at all?

2.  What rights can be ascribed to at least some actual animals?  Are some of those rights-ascriptions less controversial than others?

3.  If an affirmative answer can be sustained in the case of the first question, are there non-human animals that not only have some rights or others, but that have, in particular, a right to life.

4.  If this question seems difficult in the case of the non-human animals that actually exist, what about possible non-human animals?  Can one imagine a non-human animal to which one would be strongly inclined to ascribe a right to life?

5.  What property, or properties, are sufficient to give something a right to life?  What property, or properties, are necessary if something is to have a right to life?

6.  Is the right to life a matter of degree?  That is to say, can there be two individuals A and B, both having a right to life, but where A's right to life is a more serious right than B's right to life?

3.  Brief Comments on these Issues

3.1  Issue 1:  Do any Actual Non-Human Animals Have any Rights at all?

        The least controversial claim concerning rights possessed by non-human animals is, I think, that non-human animals who can experience pain have a right not to have pain inflicted upon them.  This would, of course, be far from uncontroversial if he term "right" were being interpreted in something stronger than the minimal way I have indicted above.  Some people, for example, hold that the possession of a right makes it not only prima facie wrong to treat an individual in a certain way, but absolutely wrong.  This claim about the concept of a right seems to me mistaken.  The point here, however, is simply that if one did interpret "rights" talk in that very strong way, then it would be very implausible to assign a right not to have pain inflicted upon them to non-human animals.  But then it would also, I would argue, be very implausible to assign that right to humans.

3.2  Issue 2:  What Rights Might be Ascribed to Non-Human Animals?

        Three rights that might be ascribed to at least some non-human animals are these:

(1)  A right not to have pain inflicted upon one;

(2)  A right to roam free, and to live as one chooses;

(3)  A right to life.

        Of these three rights, the first is the least controversial, and the last the most controversial.

        One important point, then, is that one should not assume that these rights need go together.  Thus one might hold that some animals have a right not to have pain inflicted upon them, but that only some of those have a right to live as they choose - perhaps because one thinks that some non-human animals have a capacity to experience pain, but do not have a capacity to make any choices.  Or, similarly, one might think that while many animals can make choices - for example, about what they want to do at a given time - very few of those animals have those properties - whatever they may be - that give something a right to life.

3.3  Issue 3:  Do any Actual Non-Human Animals Have a Right to Life?

        This is a very difficult question, and one cannot really answer it until one has decided what properties are such that any being possessing any of those properties has a right to life.  The main candidates that have been advanced, however, as possible possessors of a right to life are (1) some primates, (2) dolphins, and (3) whales.

        Why do some people hold that such animals have a right to life?  In the case of primates, the fact that some primates, including gorillas and chimpanzees, can learn a sign language suggests that they are capable of thought.  In addition, some of their behavior suggests that they may possess self-consciousness.  Finally, some people are impressed by some of their social behavior - especially behavior that suggests the presence of certain emotions, and concern for other members of their group.

        Similarly, although dolphins and whales cannot learn a sign language, they exhibit behavior that may indicate the presence of language, and an ability to communicate with members of their own species.  There is also social behavior that suggests the presence of certain feelings, including concern for other members of their species.

3.4  Issue 4:  Could there be Non-Human Animals that would have a Right to Life?

        Here one can consider non-human animals in science fiction books and movies that are portrayed as having the same sorts of feelings, and as possessing all of the higher psychological capacities - such as the capacities for rational thought, for communication, and for self-consciousness - that one finds in normal adult human beings.  (Consider, for example, ET.)

3.5  Issue 5:  What Properties Are Sufficient to Give Something a Right to Life?  What Properties Are Necessary?

        These two questions are among the most difficult ones in ethical theory.  But it will help one to think about these questions if one keeps two sub-issues clearly in focus:

Sub-Issue 1:  Is every property that is sufficient to give something a right to life also necessary if something is to have a right to life?  Or are some properties sufficient, but not necessary?

        In many areas, there can be properties that are sufficient to ensure that something is the case, but that are not necessary.  In baseball, for example, being a great hitter, and at least a decent fielder, etc., is sufficient to make one a very good player, but it is not necessary: one might instead be a great pitcher, and at least a decent fielder, etc.

        What is the situation in the case of properties that suffice to give something a right to life?  Are those properties also necessary?

        Consider this example.  Some philosophers have maintained that the possession of self-consciousness - where this is understood as having a sense of oneself as a subject of experiences and other mental states that continues to exist through time - is sufficient to endow an individual with a right to life.  Suppose that one thought that that was so.  The question would then arise as to whether something that lacked self-consciousness could have a right to life, or whether self-consciousness is, on the contrary, a necessary condition for having a right to life.

        This question of whether properties that are sufficient to endow something with a right to life are necessary as well is also related to the second sub-issue:

Sub-Issue 2:  If some property suffices to give something a right to life,  does the potential possession of that property by an entity also endow it with a right to life?

        This is a question that looms very large in connection with the issue of the moral status of abortion.  Suppose, for example, that any innocent thing that possesses the capacity for thought has a right to life.  What is the moral status of entities which have not yet developed sufficiently to be capable of thinking, but which will acquire that capacity if allowed to continue developing.? Do such things now have a right to life because of a present potentiality - because of a property that they will later have if they are allowed to continue to develop?

        If potentialities also suffice to give something a right to life, then presumably there will be properties - such as the actual possession of the capacity for rational thought and self-consciousness - that are sufficient to endow something with a right to life, but not necessary, since the corresponding potentiality is also sufficient.  (The potentiality, on the other hand, might be both necessary and sufficient.)

        But do potentialities give something a right to life?  That is an issue that we shall consider when we turn to the topic of the moral status of abortion.  For the moment, then, let us focus on the following question:
 

What properties, independently of any potential of giving rise to a distinct property, suffice to give something a right to life?

        What answers have been given to this question?  The main ones are, I think, the following:

1.  The ability to reason, to engage in rational thought, suffices to endow an entity with a right to life.

2.  The capacity for self-consciousness suffices to endow an entity with a right to life.

3.  The capacity for deliberation and free choice suffices to endow an entity with a right to life.

4.  The capacity for thought - that is, the capacity for having conscious mental representations of things - suffices to endow an entity with a right to life.

5.  The ability to use language, and to communicate with others, suffices to endow an entity with a right to life

6.  The ability to remember past experiences that one had, and to envisage a future for oneself, suffices to endow an entity with a right to life.

7.  The presence of a mental life that is psychologically unified over time in such a way that one can be a subject of non-momentary interests suffices to endow an entity with a right to life.

8.  Being a member of the biologically defined species, Homo sapiens, suffices to endow an entity with a right to life.

9.  Having an immaterial soul suffices to endow an entity with a right to life.

        What is one to say about these various views?  This, too, is an issue that we cannot really pursue here.  The reason is that the choice among alternatives one through seven is a very difficult one.  But one thing that should be noted is that the last two alternatives, though they would perhaps be frequently advanced in popular discussions, are regarded by most philosophers as unsatisfactory.  Why so?  As regards the view that being a member of the biologically defined species Homo sapiens suffices to endow an entity with a right to life, the problem is, as we shall see later, first, that there are strong reasons for holding that the principle in question cannot be a basic moral principle: if membership in a biologically defined species - such as Homo sapiens - is morally significant, it is because of either psychological capacities or potentialities that are typically associated with members of that species; and, secondly, that there is a strong reason for holding that membership in the relevant species cannot be sufficient by itself, because of convincing counterexamples.

        What about the thesis that having an immaterial soul suffices to endow an entity with a right to life?  Here the response will depend upon how the term "soul" is understood.  If it is understood in such a way that the possession of a soul need not involve any connection with psychological states, or capacities, or potentialities, the objection will be that basic moral principles must refer to psychological states, or capacities, or potentialities, and thus that the principle in question cannot be basic.  Often, however, the term "soul" is understood in such a way that there is a connection with psychological states, or capacities, or potentialities.  Suppose, in particular, that the idea is that of a rational soul - an immaterial entity with the capacity for rational thought.  Then philosophers would tend to agree that having a soul in that sense sufficed to give an entity a right to life.  But they would go on to argue that what was morally significant was the presence of that psychological capacity, rather than the fact that it resided in something immaterial.  The view would thus be that while a plausible sufficient condition had been formulated, it had been formulated in a less than satisfactory way, in view of the presence of an irrelevant feature - namely, that the capacity in question was a capacity of an immaterial entity.

3.6  Issue 6:  Is the Right to Life a Matter of Degree?

        Why might one think that the right to life was a matter of degree - that is, that there could be two entities, both of whom had a right to life, but where the right to life of the one was morally weightier than that of the other?  The basic idea here is that it could be both that a property that sufficed to give something a right to life admitted of degrees, and that the degree to which it was present seemed to be significant.

        A concrete illustration should help here.  Suppose that one thought that the ability to remember one's past, and to envisage a future for oneself, sufficed to give one a right to life.  These two abilities can vary enormously.  Imagine, then, an entity that can only remember what happened a minute ago, and whose ability to envisage a future is restricted to a future that is two minute long.  If you were to gradually become that sort of being, wouldn't the value that your own life had for you gradually become less?  Wouldn't you be willing, for example, to undergo a dangerous treatment to avoid such an outcome, and doesn't your willingness to expose yourself to such a risk show that a life with such a restricted memory, and such a restricted ability to envisage a future, is less satisfactory, from your own point of view, than the sort of life you presently enjoy?  But then - the argument runs - the death of a normal adult human being involves a greater loss for that individual than does the death of the individual who can only remember what happened a minute ago, and whose ability to envisage a future is restricted to a future that is two minute long.  Accordingly, if the importance of a right is a function of the seriousness of the interest that it protects, then the right to life is a more serious right in the case of a normal adult human being than it is in the case of an individual with the very restricted memory, and the very limited ability to envisage a future for himself or herself.