The mind has evolved to analyse objects from three distinct perspectives: 1) purpose, 2) design and 3) structure. The perspective we take when analysing any given object is largely determined by how useful that perspective is for us to gain knowledge and understanding of the object.
1. We can analyse objects as having a purpose. This works very well for humans, and it also works for animals. When a saber tooth tiger is running towards you, a quick analysis is required. The analysis is: 'that tiger intends to eat me'. We think of the tiger as having intent. There is no time to analyse the design or structure of the tiger. In theory, there is no reason that we can't view plants or rocks as having a purpose, except that it is not useful for us to do so.
2. We can analyse objects as having a design. This can be useful, for example, when trying to understand a leaf. We analyse it as the part of a plant designed to capture light. We think of the leaf as having a function. We can understand a leaf better by taking the design perspective than any other. It is not useful to think of a leaf as "wanting" or "intending" to capture light. We also analyse human-produced objects from the design perspective, thinking of them in terms of their function.
3. We can analyse the structure, the physical properties of all objects. In some cases, where the above two perspectives are not useful at all, it is our only way of getting an understanding of the object. To understand a rock means to understand its structure; there is no additional usefulness from thinking of the rock from either the design perspective or the purpose perspective.
Praxeology is the study of what can be learned by contemplating, and drawing logical deductions from, the concept of action. Action is purposeful behaviour. Praxeology is therefore an example of taking the purpose perspective towards analysing objects.
Praxeological laws apply wherever there is action, that is, wherever we perceive an object as behaving with intent and purpose. The observation that most human behaviours are actions, that is, that humans are an example of beings that are usefully considered as purposeful beings, implies that praxeology is a very useful way of thinking about human behaviour. However, there is no particular reason why praxeology should be limited to humans. Non-human objects can also be usefully analysed as actors, such as the example of the saber tooth tiger above.
We may ask: is a saber tooth tiger really an acting being? That is, is the tiger really making choices about his behavior, or are its behaviors entirely instinctive? This question is really meaningless, however, when we consider purposefulness not as an attribute inherent to objects, but rather as an attribute that minds imbue onto objects, when it is useful to do so.
A purposeful behaviour (i.e. an action) is a behaviour that has been deliberated about and chosen over other behaviours. I have a clear conception that my own behaviours can be categorized into those undertaken with a purpose (e.g. typing on my keyboard), and those that are reflexes (e.g. sneezing). I then extrapolate this personal insight about me onto other human beings. I assume that the behaviours of other humans are not all reflexes. I assume that other human beings behave with a purpose, i.e. with intent, i.e. that other humans, like me, act.
I do this purely because it is more useful for me to think of other humans as acting beings, rather than purely reflexive beings. I do not know for certain whether other human beings are really acting; it is possible that everyone else, except for me, is purely reflexive and not really making choices at all.
In short, purposefulness/consiousness is not something inherent to objects. It is a word that denotes those objects that we can usefully analyse using a certain mode of analysis: the perspective of intent, desire, action. Praxeology is an example of this mode of analysis, and it may apply to any being that we find it useful to consider as purposeful - human or otherwise.
Note: This was originally posted as part of a conversation here at the Mises forum.