Conclusion 11: Behaviour by an organism which conforms to a fixed pattern or rule is not a sufficient warrant for ascribing cognitive mental states to that organism, even if stimulus-response coupling is indirect.

Definition - "fixed pattern"

We can mathematically represent a pattern of behaviour in an organism by an output variable (say, z). A fixed pattern can be defined as a pattern where the value of the output variable z remains the same, given the same values of the input variables. This definition has two surprising implications. First, suppose that we can describe a piece of behaviour in an organism using a mathematical function F and some input variables (or parameters) x1, x2, x3, ... xN, where the value of the output variable z is F(x1, x2, x3, ... xN). The above definition entails that even when the values of x1, x2, x3, ... xN vary over time, the behaviour still conforms to a fixed pattern, so long as the function F remains the same.

Another surprising implication is that even in a fixed pattern, the value of the output variable z may be determined by two or more different functions, depending on the values of the inputs.

Definition - "flexible behaviour"

If the program governing an organism's behaviour changes over time, such that the value of an output variable z is no longer the same for the same inputs, whether because of a change in the function(s) which define the value of z, or the parameters of the function(s), or the conditions in the program under which the function(s) are invoked, then the behaviour described by z is flexible.

In other words, truly flexible behaviour requires not just new values of output variable for different values of the inputs, but new patterns of output, new kinds of input, or new conditions under which the output patterns are generated.

Conclusion 12. The existence of memory in an organism is a necessary but not a sufficient condition for learning.

Conclusion 13. Learning should not be attributed to an organism unless it displays a change in its pattern of behaviour which it is able to reproduce on a subsequent occasion.

Conclusion 14: The occurrence of non-associative habituation and sensitization in an organism does not provide a sufficient warrant for the ascription of mental states to it. (Corollary of Conclusion 11.)

Conclusion 15: An organism must possess modifiable patterns of information transfer before we can justifiably ascribe cognitive mental states to it. (Corollary of Conclusion 11. The term "modifiable" means the same as "flexible", defined above.)

Conclusion 16: A pattern of behaviour by an organism must be generally adaptive or neutral before we can regard it as a manifestation of a cognitive mental state.

Conclusion 17. All organisms exhibit flexible behaviour, to some degree.

Conclusion 18: Flexible behaviour alone is not a sufficient condition for the existence of mental states. Internally generated flexibility of behaviour (i.e. the ability to modify patterns of information transfer, by means of an inbuilt mechanism) is a necessary condition for the existence of cognitive mental states in an organism.

Conclusion 19. The capacity for associative learning in an organism is a sufficient condition for its being able to engage in internally generated flexible behaviour.

Conclusion 20. The occurrence of action selection in an organism does not provide a sufficient warrant for the ascription of mental states to it.

Conclusion 21. The existence of a nervous system in an organism does not provide a sufficient warrant for the ascription of mental states to it.

Conclusion 22. The occurrence of centralised action selection in an organism does not provide a sufficient warrant for the ascription of mental states to it.

Conclusion 23: The ability of an organism to undergo classical and/or instrumental conditioning is a sufficient condition for its being able to learn, in the philosophical sense of the word.

Conclusion 24: The presence of flexible behaviour patterns that are acquired through an internal mechanism in an organism is a necessary but not a sufficient condition for our being able to identify its cognitive mental states.

Conclusion 25: A capacity for learning is a necessary but not sufficient condition for the existence of mental states in an organism.

Conclusion 26: The identification of associative learning in an organism does not establish that it has cognitive mental states.

Conclusion 27. An animal can be described as undergoing operant conditioning if the following features can be identified:

(i) innate preferences or drives;

(ii) motor programs, which are stored in the brain, and generate the suite of the animal's motor output;

(iii) an action selection mechanism, which allows the animal to make a selection from its suite of possible motor response patterns and pick the one that is the most appropriate to its current circumstances;

(iv) fine-tuning behaviour: efferent motor commands which are capable of stabilising a motor pattern at a particular value or within a narrow range of values, in order to achieve a goal;

(v) the ability to store and compare internal representations of its current motor output (i.e. its efferent copy, which represents its current "position" on its internal map) and its afferent sensory inputs;

(vi) direct or indirect associations between different motor commands, sensory inputs (optional) and their consequences, which are stored in the animal's memory and updated when circumstances change;

(vii) a goal or end-state, which is internally encoded as a stored memory of a motor pattern or sensory stimulus that the fly associates with attaining its goal;

(viii) a pathway for reaching its goal, which is internally encoded as a stored memory of a sequence of movements or sensory stimuli which allows the animal to steer itself towards its goal;

(ix) sensory inputs that inform the animal whether it has attained its goal, and if not, whether it is getting closer to achieving it (the latter part is optional);

(x) a correlation mechanism, allowing it to find a temporal coincidence between its motor behaviour and the attainment of its goal;

(xi) self-correction: abandonment of behaviour that increases, and continuation of behaviour that reduces, the animal's deviation from its desired state.

Conclusion 28: Animals that are capable of undergoing operant conditioning are bona fide agents that possess beliefs and desires.

Conclusion 29. We are justified in ascribing agency to a navigating animal if the following features can be identified:

(i) a goal or end-state, which is internally encoded as a stored memory of a visual stimulus that the fly associates with attaining its goal;

(ii) sub-goals, which are internally encoded as stored memories of visual stimuli that help the fly attain its goal;

(iii) a pathway for reaching its goal, which is internally encoded as a local vector or a stored memory of a sequence of movements which allows the animal to steer itself towards its goal;

(iv) exploratory behaviour, as the insect tries to locate food sites;

(v) visual inputs that inform the animal about its current position, in relation to its goal, and enable it to correct its movements if the need arises;

(vi) direct or indirect associations (a) between visual landmarks and local vectors; (b) between the animal's short term goals (landmarks) and long term goals (food sites or the nest). These associations are stored in the animal's memory and updated when the animal's environment changes;

(vii) the ability to store and compare internal representations of its current motor output (i.e. its efferent copy, which represents its current "position" on its internal map) and its afferent sensory inputs. Motor output and sensory inputs are linked by a two-way interaction;

(viii) fine-tuning behaviour: efferent motor commands which are capable of steering the animal towards a short or long-term goal. It has to be able to detect both matches (correlations between its view and the stored image of its goal) and mismatches or deviations - first, in order to approach its goal, and second, in order to keep track of it;

(ix) self-correction: abandonment of behaviour that increases, and continuation of behaviour that reduces, the animal's deviation from its desired state.

Conclusion 30. The capacity for rapid reversal learning in an animal does not, by itself, warrant the ascription of mental states to it.

Conclusion 31. Progressive adjustments in serial reversal tests constitute good prima facie evidence that an animal is trying to adjust to sudden changes in its environment, by rapidly revising its expectations.

Conclusion 32. An animal's ability to form categorical concepts and apply them to novel stimuli indicates the presence of mental processes - in particular, meta-learning.

Conclusion 33. An animal's ability to identify non-empirical properties (e.g. sameness) is a sufficient condition for its having mental states (intentional acts). Such an animal can apply non-empirical concepts, by following a rule.

Which organisms have mental states?

Bacteria? - No. They're flexible, but their flexibility isn't internally generated.

Protoctista? - No. Ditto. However, they are capable of being habituated.

Plants? - No. Ditto. However, they are capable of being habituated.

Simple animals (sponges)? - No. Ditto. However, they are capable of being habituated.

Cnidaria (e.g. jellyfish)? - No. Ditto. However, they do have a nervous system, action selection and fast escape mechanisms in some species.

Worms? - No. They possess internally generated flexibility (associative learning), but do not appear to be capable of undergoing operant conditioning. There's no evidence that they can fine-tune their motor movements or that they use an internal map of any sort.

Insects? - Yes. They can undergo operant conditioning and can navigate. Some of them can form concepts.

Cephalopods? - Yes. They can navigate.

Vertebrates? - Yes.