If you replace a knife's handle, and then you replace the blade, is it still the same knife?

Answer 1

Not if it's a Soul Blade!

I see where you're going with this. This is a dilemma for question of personal identity: what makes you the same person as you were yesterday, or last year, or 10 years ago? If the basis for that identity depends on having the same body (more about your brain, actually), then that could be problematic when you realize that your physical cells die and are replaced over time, so you don't share all the same cells as you had 10 years ago.

Further, imagine in the not-too-distant future when scientists can start to replace parts of your body and brain with artificial or transplanted parts. Would you still the same person? At what point in this replacement process would you cease to be the same person...10%, 25%, 50%, 75%, etc.? How could you possibly defend any given (arbitrary percentage)??

Now, the case with a knife (or a chair) is slightly less complicated, because there's no mental process or personality to complicate the issue. Nonetheless, it's still a tricky question. If you say that it's the same knife after only the handle is replaced, then why exactly is it different after the blade's been replaced too? Is the blade the all-important feature of a knife; if so, why? What if it was a scrimshaw knife (carved whale bone as a handle); wouldn't the handle be the defining part of the knife then?

Our intuition says that if you replace everything about a knife, then it's no longer the same knife as it was before. But the trick is drawing that line: at what point does it cease to be the same knife? Is there a magic number for the percentage of its original parts an object must retain before being deemed "not the same"?

Maybe "sameness" or strict identity doesn't really exist with physical objects, because physical objects are always changing. Even the "same knife" sheds molecules as it cuts (that's how it gets dull), and it picks up molecules of what is being cut (traces of blood, for instance). And not to mention that all matter is constantly in motion, because each atom/molecule vibrates (with electrons swirling around and generating some kind of electromagnetic field). So the concept of "being the same" might need to be defined better...

P.S. Our intuition describe above could be wrong: if it turns out that personal identity hinges on memory and/or personality, and all those can be replicated by software (some day) or uploaded into a computer (and copied?!), then our physical body and brains don't matter for personal identity. Think of Star Trek: the teleportation device, at least under one understanding of it, seems to destroy the body in place A and then reconstruct it with different atoms in place B; so those two bodies are physically different...yet we still want to say that it's still the same person (otherwise, who would want to enter such a device, if it meant dying??!)....

Answer 2

Sameness implies that an object remains static. Any modulation or change to an object, changes the object. So from this view point, once you replace any part of the knife, the knife is no longer the same knife. The object may still be a knife, however it is a metaphysically different knife. Further modulation only proves that the knife is no longer the same knife.

This sort of goes along the question, Can you step in the same river twice?

-Kerplunk288

Answer 3

There are several ways to look at this question. Philosophically, and verbally, a handle is a handle, a blade is a blade, and a knife is a knife. All of these words are only symbols for what we are actually manipulating. There are so many words (symbols) that we can use to express ourself concerning these changes, but the one thing that will never change is that what we are dealing with is a 'knife's handle' and the 'knife's blade'. even though the metal changes and even though the wood changes, we are still dealing with the same knife. That is, unless you want to call this thing by a different name. So, I guess my answer would be, yes, it is still the same knife; it is just made of different materials.

Answer 4

No. That is the totality of the knife. The same would be true if you replaced every part on a car. It is no longer the same car.

Answer 5

You will have a whole new knife, is there a joke hidden in here somewhere?

Answer 6

I'd say it is and it isn't. In your own mind, it is the same knife, but in physical fact it is not.

Answer 7

If someone replaced your brain, and then replaced your body, would you still ask stupid questions?

Answer 8

no. It is different as the parts are different.

Answer 9

i dont really think so, but what's the catch?

Answer 10

tree in the woods,,,,one hand clapping ,,,stuff like that,,,,,,,NO.