Detecting design or intent in nature

[Heywood]

If his argument goes that all the evolutionary systems he's seen for which the origins are known are the result of intelligence, therefore all evolutionary systems are the result of intelligence, Heywood is making an arbitrary decision to cut things off at generic intelligence, when that's not at all the full scope of what he's saying. In reality, not only are all the evolutionary systems with origins he knows of the result of intelligence, they're specifically the result of human intelligence.

Remember human and intellect are not the same thing. Now consider the following two propositions:

Proposition 1:Evolutionary systems require intellect.
Proposition 2:Evolutionary systems require humans.

Showing proposition 2 false does not falsify proposition 1.

Your counter argument here fails.

Yes, but if you're trying to advance the probability of design on the basis of observations that we've made, it's equally true that the only effective observations you have as to the origins of intelligence places that intelligence squarely on Earth. You have no observations of intelligence arising anywhere else.

I have no observations of intelligence arising anywhere other than earth because I haven't left earth and looked for it. If and when I do, the more worlds and places I examine and find no intellect, the more likely it becomes that earth is the only place where there is intellect. To come to the conclusion, as you would have me to do, that the earth is the only place where there is intellect, requires me to actually make some observations of places other than earth.

Even if that comes to pass, that I come to the conclusion that the earth is the only place which harbors intellect, how does that invalidate the proposition that evolutionary systems require intellect?

Your answer is that we observed an evolutionary system create intellect. But we have also observed intellects creating evolutionary systems. The existence of the evolutionary system which created us does not falsify the proposition that said evolutionary system itself required an intellect. You really have no way of knowing what came first....the intellect or the evolutionary system.

Your position, to even be tenable, requires you to believe that evolutionary systems can come into existence without an intellect, but you do not have any direct observations to support that position. My position has direct observations of evolutionary systems requiring intellect, and no direct observations contradicting it.