Ground&Pound

I thought I'd spin off of the original post since it "evolved" away from the initial question of circular arguments in science.

This may amateur attempt to find a circular argument in science...


Question: Where does a cell get the code to make its DNA?

Answer: From DNA.

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I have my on thoughts on whether or not this is a circular argument, but I'd like to hear from some others.

LkwdSteve

"Where does a cell get the code to make its DNA?"

It doesn't (is my "amateur" answer). It's replicated from prior cells. There must be a prior cell. Sometimes the replication isn't exact, thus you get mutation or (micro) evolution. The real question is not where cells get DNA, it's how did the very first cell (life) come about. What was the nature of the very first cell that was able to replicate? How did the very first primative DNA come about?

Was it some type of self-organizational feature of Earth matter surrounded, at the same type, by the proper environment?

No. I don't think there's anything like circular reasoning as scientists investigate these questions.

This answer is from the cheap seats, of course.

LkwdSteve

Obviously, I think the wording of the question is "loose" or misworded. In that vein, there is a similarly "loose" answer that might be considered relatively accurate depending on interpretation of the wording:

"Where does a cell get the code to make its DNA?"

From sperm.

Hopefully this gets my point across that intead of "making" (from scratch, as it were, cells OR DNA) you have a continuous chain of "replicating" (simply copying). Cells don't make DNA, but rather provide a vehicle for it's replication. When the chain breaks, you get extinction.

Ground&Pound

A sperm cell.

LkwdSteve

YES.

Remember that the cell is the necessary vehicle to carry the replicated DNA. The cell is the motor vehicle (in my case a Porsche).

Additional thought (growth activity):

In any particular individual or entity, DNA will have "roadmapped" the generation of a wide variety of different types of cells. Every single one of those cells as different as they may be, will contain DNA that is identical in every case. I think it is reasonable to describe growth activity as DNA constructing cells that then interact with the environment around the entity. This construction consists of a great series of cell divisions with changes to some of the cells without any changes to the imbedded DNA.

Second additional thought (birth activity):

Sperm is only half of the answer. Ova is the other half. The combination of the two "creates" new DNA. What is the most appropriate way to describe this action? That the cells are combining at the behest or direction of their resident DNAs, or that cells are making DNA? To say that the cells are making DNA seems too simplistic to me as a description of what is going on.

Summing up:
To assert that a circular argument exists here, requires equivocation on the word "making". DNA "makes" cells in the sense that it provides a blueprint or roadmap. Makes=directed contruction. A single cell "makes" DNA in a different sense when it divides. Makes=passive replication. Two cells "make" new DNA in another different sense. Makes=passive combination. Different meanings of the word "make" are combined into one argument as if they were the same.

FloggingSully

"Question: Where does a cell get the code to make its DNA?

Answer: From DNA"

G&P this is not a circular argument because it is not an argument, it's a question and an answer instead of a series of premises leading to a conclusion.

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LkwdSteve

I called the wording loose, you are saying it better FloggingS. We have description as opposed to argument.

I wonder if you can even construct an argument here.

Premise 1. It is true that a cell receives instructions for creating DNA.
And,
Premise 2. It is true that DNA is the source of those instructions.

Then (if both of the above are true) it is the case that: ?????????

Whatever conclusion you might come up with, I think premise #1 is inadequate/faulty/not true etc. anyway.

Spider

New cells arise from the division of old cells (remember mitosis from high school biology?). The chromosomes in the nucleus of a cell divide and a duplicate set of chromosomes goes to each new cell. In the case of a sperm and an ovum, each gamete (reproductive cell) has half the normal number of chromosomes (haploid number), so the zygote resulting from their union has the normal number of chromosomes, but with half of its DNA from one parent and half from the other.

If you want to discuss where the first cell or "original" DNA came from, that's a whole other issue.

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Ground&Pound

Let me try to rephrase....

1. New cells are constructed from a DNA blueprint.

2. The DNA blueprint is supplied by a previously existing cell.

Circular arguement ... how can cells come from DNA when DNA comes from cells?

Spider

Cells don't come from DNA, they come from the division of cells. When the cell divides, it gives each new cell a copy of its DNA.

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