ICANT writes:
My grandmother being a 100% mortal human being.
Me being a 100% spiritual being.
My father being a 50% human being and a 50% spiritual being would be a transitional.
I'm going to try and take your example and show how it reflects on what a scientific transitional would be like. This won't be exact, and I'm really trying to work with your terminology. But if you take this, and what everyone else is saying, I hope it will make some sense.
First Edit - Things don't change that fast.
Your example has a transition going from 0 -> 100% in 2 generations. This isn't observed as far as I know. Observations see things more like this:
Generation 00000 - 100.00% Mortal, 000.00% Spiritual
Generation 00001 - 099.99% Mortal, 000.01% Spiritual
Generation 00002 - 099.98% Mortal, 000.02% Spiritual
...
Generation 04323 - 056.77% Mortal, 043.23% Spiritual
Generation 04324 - 056.76% Mortal, 043.24% Spiritual
Generation 04325 - 056.75% Mortal, 043.25% Spiritual
...
Generation 09998 - 000.02% Mortal, 099.98% Spiritual
Generation 09999 - 000.01% Mortal, 099.99% Spiritual
Generation 10000 - 000.00% Mortal, 100.00% Spiritual
And "transitional" is every generation between the two ends (each and every 9,999 of them). Also, in your analogy, your father being 50% mortal human and 50% spiritual human is still a fully formed, fully functional "person". As is your grandmother, and you. As is every person in each generation I've provided (all 10,001 of them)
Second Edit - Things don't change that uniform.
Your example has a transition going from 0 -> 100% in uniform steps. The transitions of creatures aren't always done this strictly. Sometime's it's faster, sometime's it's slower, and it's not even always directly balanced (% Mortal + % Spiritual generally doesn't = 100%). Observations see things more like this:
Generation 00000 - 100.00% Mortal, 000.00% Spiritual
Generation 00001 - 100.00% Mortal, 000.02% Spiritual
Generation 00002 - 100.00% Mortal, 000.03% Spiritual
Generation 00003 - 099.99% Mortal, 000.04% Spiritual
Generation 00004 - 099.98% Mortal, 000.05% Spiritual
Generation 00005 - 099.93% Mortal, 000.05% Spiritual
Generation 00006 - 099.93% Mortal, 000.08% Spiritual
...
Generation 04323 - 054.38% Mortal, 052.23% Spiritual
Generation 04324 - 054.36% Mortal, 052.24% Spiritual
Generation 04325 - 054.35% Mortal, 052.24% Spiritual
Generation 04326 - 054.35% Mortal, 052.36% Spiritual
Generation 04327 - 054.35% Mortal, 052.37% Spiritual
Generation 04328 - 054.32% Mortal, 052.37% Spiritual
Generation 04329 - 054.31% Mortal, 052.37% Spiritual
Generation 04330 - 054.26% Mortal, 052.39% Spiritual
...
Generation 09994 - 000.12% Mortal, 099.98% Spiritual
Generation 09995 - 000.08% Mortal, 099.98% Spiritual
Generation 09996 - 000.03% Mortal, 099.99% Spiritual
Generation 09997 - 000.02% Mortal, 100.00% Spiritual
Generation 09998 - 000.02% Mortal, 100.00% Spiritual
Generation 09999 - 000.01% Mortal, 100.00% Spiritual
Generation 10000 - 000.00% Mortal, 100.00% Spiritual
Again, each generation is a fully functional, complete person, and a transitional.
Third Edit - Things don't "start" and "stop" changing, they just change as time goes on.
Your example has a transition going from 0 -> 100% But we never see this in any observations. When is a "fin" done for a fish? When is an "eye" complete? There generally isn't any beginning or any end. Observations see things more like this:
...
Generation-00004 - 100.04% Mortal,-000.01% Spiritual
Generation-00003 - 100.03% Mortal,-000.01% Spiritual
Generation-00002 - 100.01% Mortal, 000.00% Spiritual
Generation-00001 - 100.01% Mortal, 000.00% Spiritual
Generation 00000 - 100.00% Mortal, 000.00% Spiritual
Generation 00001 - 100.00% Mortal, 000.02% Spiritual
Generation 00002 - 100.00% Mortal, 000.03% Spiritual
Generation 00003 - 099.99% Mortal, 000.04% Spiritual
Generation 00004 - 099.98% Mortal, 000.05% Spiritual
Generation 00005 - 099.93% Mortal, 000.05% Spiritual
Generation 00006 - 099.93% Mortal, 000.08% Spiritual
...
Generation 04323 - 054.38% Mortal, 052.23% Spiritual
Generation 04324 - 054.36% Mortal, 052.24% Spiritual
Generation 04325 - 054.35% Mortal, 052.24% Spiritual
Generation 04326 - 054.35% Mortal, 052.36% Spiritual
Generation 04327 - 054.35% Mortal, 052.37% Spiritual
Generation 04328 - 054.32% Mortal, 052.37% Spiritual
Generation 04329 - 054.31% Mortal, 052.37% Spiritual
Generation 04330 - 054.26% Mortal, 052.39% Spiritual
...
Generation 09994 - 000.12% Mortal, 099.98% Spiritual
Generation 09995 - 000.08% Mortal, 099.98% Spiritual
Generation 09996 - 000.03% Mortal, 099.99% Spiritual
Generation 09997 - 000.02% Mortal, 100.00% Spiritual
Generation 09998 - 000.02% Mortal, 100.00% Spiritual
Generation 09999 - 000.01% Mortal, 100.00% Spiritual
Generation 10000 - 000.00% Mortal, 100.00% Spiritual
Generation 10001 --000.01% Mortal, 100.01% Spiritual
Generation 10002 --000.01% Mortal, 100.02% Spiritual
Generation 10003 --000.04% Mortal, 100.02% Spiritual
Generation 10004 --000.05% Mortal, 100.02% Spiritual
...
As you can see, the 00000 generation is simply a transitional as well. Along with the 10000 generation. This is what is meant when people say "every creature is a transitional".
There generally isn't really a point where we can say this is "100%" or "0%" anything. I'm sure you know the octopus has a better eye than us. And that we have a better eye than a mole. So, is our eye "80%"? 80% of what? What's 100% eye? What if 100% is something that may be evolved in the future? We don't even have a base-line to judge these things in percentages.
I hope this quick tweaking of your example can help show what is meant by a scientific transitional.
That is:
50% Mortal and 50% Spiritual is a transitional.
42% Mortal and 45% Spiritual is a transitional.
08% Mortal and 75% Spiritual is a transitional.
20% Mortal and 20% Spiritual is a transitional.
20% Reptile and 20% Bird is a transitional.
Other Things to consider:-my choice of 10000 generations was simply to show that it's "lot's bigger than 2". It may just as easily be 1,000,000,000 or larger.
-some (a lot of?) evolution isn't new things coming and old things going, but just things being used differently than they were before (jaw-bones becoming ear-bones, for example).
-most evolution involves a lot of branching off. That is, Generation 04237 may have one offspring that is Generation 04238 on it's way to you (Generation 10000). But the same Generation 04237 may also have an offspring that is Generation 04238b that starts on it's way towards Generation 10000b that is 25% Mortal, 60% Spritual and, say, 15% Supernatural. Observation shows that this happens a lot. Even Generation 04238b's later Generation 07155b can split and start 07156c... which can also eventually split and so on...