Is the following application of Kant's Categorical Imperative valid?

Question

I'm reading about Kantian ethics and my question is if the maxim/prescription "Increase my Darwinian Fitness" is valid according to Kant's Categorical Imperative.

Answer 1

Finding out whether a proposed maxim is, in fact, a valid categorical imperative goes something like this:

1. Suppose everyone followed the maxim, x.
2. If everyone followed the x, does a contradiction in terms result?
3. If a contradiction results, x is not a valid maxim. Otherwise, x is a valid maxim.

An Example:

Suppose lying were always justified and that all people lied constantly without ever telling the truth. Since lies are all that exist in this scenario, you couldn't logically define what the truth is to another person, because your definition must be untrue (everyone, including you, always lies.) So, in your attempt to define the truth, you produce another lie. Thus, communication becomes an exercise in fantasy where even describing what the truth is becomes impossible; there would be no need for a word like "truth." Without a concept of truth, the concept of a lie (the absence of truth) no longer makes sense either. This is a contradiction in terms: assuming everyone always lies, lying then becomes impossible.

However, if everyone told always told the truth, we would not have this same contradiction in terms. I could simply prefix any lie with the statement, "This is a lie: (insert lie here)." In this scenario, where everyone tells the truth all the time, the logical definition of a lie still makes sense, because one person can reliably communicate the properties of a lie to another person; the fact that everyone always tells the truth guarantees this.

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So, to answer your question, we replace x in the three steps outlined above with the candidate-maxim "Each individual is obligated to increase their own Darwinian fitness." Suppose this maxim were adopted by all people, would that result in the breakdown of the definition of "increasing Darwinian fitness"?

Well, it's not yet clear what that definition is. Only after we have a precise definition of the candidate maxim can we attempt to derive a contradiction. How do we measure Darwinian Fitness? Is it probability of survival? Is it the ability to pass genes on to the next generation? What if you have two individuals, one who is healthy but relatively infertile, while the other agent is sickly, but fertile. Which agent is considered more fit?

Let's suppose you're talking about probability of survival (with fertility assumed equal for all individuals.) If that's the case, survival in what context (On Earth, Mars, the tropics, the arctic)? Some adaptations that are helpful in some environments can be detrimental in others. An additional complicating factor is the role group selection has in an individual's survival. When each individual in a group is helped by others, the group, as a whole, generally has a better survival rate than any lone individual. But, sometimes individuals can cheat to increase their own potential for survival (perhaps by hoarding resources.) Who's more fit, the team player or the cheater?

It's not possible to have a conversation about the validity of this maxim, until the maxim is better defined. However, I'll anticipate where I think you were going with this with a discussion of "positive duties." It's been taken, in perfectionist ethics, that Kant generally supported the idea of improving one's self:

Positive duties, by contrast, are duties to exercise one’s capacity to develop one’s nature and/or to realize perfectionist goods. For example, one has a duty to develop one’s talents and not to devote one’s life entirely to idleness and pleasure (Kant 1785). source

*(Kant 1785) Refers to The Metaphysics of Morals

However, this has little to do with notions of perfection relating to "Darwinian Fitness" and more to do with with an individual achieving Eudaimonia. Supposing you had a working definition of "Darwinian Fitness," you would need to argue that maximizing fitness is either an objective good or that fitness is somehow an expression of human nature. But again, it all starts with the definition; without a clear-cut definition of fitness that can differentiate between objectively fit and unfit individuals, any argument (Kantian or otherwise) is invalid. My suspicion is that such an objective definition of individual fitness is impossible, because fitness changes depending on the environment, which means for a single individual, there are as many definitions of fitness as there are environments.