(The key IOE passage here seems to be pg 70-71)
Ayn Rand writes that “the requirements of cognition forbid the arbitrary grouping of existents”. What would constitute arbitrary here?
Lets take a fairly extreme example to explain what I’m getting at. Imagine a fictional totalitarian country called Libonia, currently perishing under the cruel tyranny of King Asbad. Asbad, never widely praised for his mental stability, has an intense dislike of red things, banjos, and hats that are over 3 inches tall. In fact, he dislikes them so intensely that his secret police have been instructed to execute anyone found to be displaying one of these objects in public. After numerous people have been killed, the residents of Libonia form the concept “things King Asbad dislikes”, which has the aforementioned referents “red objects, banjos and big hats”. They invent a name for this concept, lets say “asbadphobians”, and start to use it in daily conversation. Now, would this concept be valid?
The question seems to rely on whether a concept formation solely involves qualities that are objectively ‘present’ in entities, or whether it can be also be based on their functional properties - the roles they play in our day to day life. Although asbadphobians have nothing in common which could be found by an outside observer simply looking at them, or by a scientist studying their molecular properties, they undoubtably have a strong significance in the life of Libonians. So significant, in fact, that if they forget which objects are asbadphobian they are likely to end up dead. In this sense, the concept is in no way arbitrary.
In IOE, Ayn Rand gives the example of the steps involved while forming the concept ‘table’, and I disagree with part of this. Her claim is that the concept of ‘table’ is first formed based on a perceptual similarity of shape - tables are flat round objects with supports. I would claim that the concept of ‘table’ is first formed by looking at functional properties - a table is just ‘any object people put their food on while eating regardless of shape’. We can imagine a street where every household has tables which are completely different shapes from the other households (maybe they are all big fans of modern art and like triangular tables, and so on), and yet I doubt a child would have any difficult whatsoever in forming the table concept. He will see people eating from these tables and will hence recognise the role they play in life, regardless of whether they have anything intrinsically in common. The same thing applies to chairs - chairs come in all shapes and sizes (stools, kitchen chairs, beanbags, armchairs, etc etc) all of which have pretty much nothing in common, yet they are united purely by their functional properties - a chair is something which people sit on. Even if I’m wrong here, Ayn Rand’s claim is by no means obvious and really lies in the domain of emprical psychology rather than philosophy.
I would say that as long as a grouping of objects plays some role in the life of a person, an integration of that grouping into a concept will be valid regardless of whether these objects actually have anything in common. I’m not sure to what extent Ayn Rand would have agreed or disagreed with this, and cant really find anything in her work where it is discussed.