Philosophy 382
Bradford Skow

	
							Fitness
							
							
Definitions:

	The viability of organism X =df. the probability that X will survive into
	adulthood.
	
	The fertility of organism X =df. X's expected number of offspring.
	
	The fitness of organism X =df. the product of X's viability and X's fertility.
	
	The fitness of trait A =df. the average fitness of organisms with trait A.
	
	Trait A is fitter than trait B =df. the fitness of trait A is greater
	than the fitness of trat B.
	
	
	Trait T is advantangeous =df. an organism that has T is fitter than an
	organism that lacks T but is otherwise the same.
	
	
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Interpretations of probability:


Actual Frequentism:

(AF)	The probability of X is r =df. the frequency of events of the same 
		type as X in the reference class is r.
		

An argument against (AF):


1.	If (AF) is correct, then the probability that the coin lands heads is 1.

2.	The probability that the coin lands heads is not 1.

3.	Therefore, (AF) is not correct.




Hypothetical Frequentism:

(HF)	The probablity that the coin will land heads =df. If we had tossed to 
		coin over and over again, the frequency of heads among all the coin 
		tosses would have gotten closer and closer to 1/2.
		


An argument against (HF):


1.	If we had tossed the coin over and over again, then the frequency of heads 
	might have stayed at 1.
	
2.	If P1, then (if (HF) is correct, then the probability that the coin will
	land heads is not 1/2).
	
3.	Therefore, if (HF) is correct, then the probability that the coin will land
	heads is not 1/2.
	
4.	The probability that the coin will land heads is 1/2.

5.	Therefore, (HF) is not correct.




Subjectivism:

(S)		The probability of X is r =df. my level of confidence that X happens is 
		r.



Two arguments against subjectivism:


	1.	Fitness is an objective property of organisms.
	
	2.	If the subjective definition of probability is correct, then
		fitness is not an objective property of organisms.
	
	3.	Therefore, the subjective definition of probability is not correct.
	
	

	
	1.	If the subjective definition of probability is correct, then the
		viability of zebra A is not equal to the viability of zebra B.
		
	2.	The viability of zebra A is equal to the viability of zebra B.
	
	3.	Therefore, the subjective definition of probability is not correct.
	
	

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An argument that evolution is not a scientific theory:


			(*)	The fit organisms survive.



1.	(*) expresses the entire content of the theory of evolution.

2.	(*) is a tautology.

3.	If (1) and (2), then the theory of evolution is not a scientific theory.

4.	Therefore, the theory of evolution is not a scientific theory.