[hist-analytic] Materialism and mass as a unit of measurement

Baynesr at comcast.net Baynesr at comcast.net
Sat Jan 29 12:21:58 EST 2011

What I posted was directed against Block and Stalnaker's view of the role of identities in explanation, particularly where the identities are asserted to hold between neural and mental events. It wasn't a criticism of materialism as such. 

My approach is to allow the physicalists to run with the ball so that the burden of proof is on them, not me, whence my attack on their approach rather than an attack on materialism which as the new orthodoxy takes numerous forms. Now to some specifics. 

"I don't see an ambiguity in e = mc^2 which applies really to both." 

Ok, then in the case of a photon which has no mass, what does 'M' in 


mean? Is its meaning the same, then, as it is in 

'P = MV'? 

Or, does it merely take different values? If a photon is massless and M is 0 then then E is, likewise, 0. So either the mass of an electron is not zero or we "fiddle" with 'M' (the "equivocation"). We know that a photon has a great deal of momentum, so it does have energy, etc. However, I am pleased that you take it that the equation applied to both because the question of the meaning of 'M' in the characterizing the momentum of a photon becomes significant, given that it is massless, although the value of M can't be 0 in the equation as long as the photon is said to have E. 

The question of units arises because a difference in units is the only way to justify attributing a value of M to a massless particle, assuming there is no ambiguity and, therefore (apparently on the view you take) we need not write it like this: 

E(rest energy) = M(rest mass)C^2. 

But if we DO require this emendation of the classical formulation then I would persist in saying there is an issue. 

The problem with Kim (and I do have specific since there are as many flavors of physicalism as there is ice cream) is that he claims there is only matter; but he gives us no idea of what matter is. This is the fount of my skepticism. All accounts of what it is to be physical that I've seen depend on "realizers" of the laws of physics, which brings us to the question What are the laws of physics? The answer is usually "Generalizations over physical quantities." Circularity prevails. Physics is concerned with mass, not "material objects." But there may be a version of physicalism that identifies the two. I think some philosophers such as Kim make this assimilation; it was against them that my remarks were directed. I don't believe there are material objects; I believe there is mass, whence the importance of justifying any assertion to the effect that a photon is either a massed "quantity" or a material object. It is a subject matter of physics, but why? I.e. if we assume that physics deals with objects having mass. If mass IS energy then the move we've been talking about is merely "pencil and paper" (dealing with the conversion of units); if they differ then materialism cum Kim et al is false or unexplained. They can differ even if there is an equivalence relation between them. 



----- Original Message ----- 
From: "Roger Bishop Jones" <rbj at rbjones.com> 
To: hist-analytic at simplelists.co.uk 
Sent: Saturday, January 29, 2011 10:26:12 AM 
Subject: Re: Materialism and mass as a unit of measurement 


I didn't understand much of your reply Steve, but we may be 
on a hide-into-nothing since I don't know anything of Block- 

So far I don't see anything that has force against 
materialism. Possibly you could amend your argument to 
reflect the points I made and post it again. 

Other questions: 

I have not grasped what you are calling the "ambiguity" of 
You say my points all concern this, but I would say if 
anything that they all relate to the distinction between 
total mass and rest mass, and I don't see an ambiguity in 
e = mc^2 which applies really to both. 

In general I think in relativistic equations you should 
always take M to be total mass. 
On the occasions where rest mass is mentioned, it is always 
specially indicated, usually as m_0. (m subscript zero). 

On the question of whether there is a problem with units, 
again I don't see it. 

Are you rejecting the materialist position because you don't 
think that a proton really is material, because it has no 
rest mass? 

Presumably you can't be a rest-materialist and have a theory 
in which the only thing which exists is rest mass. 
(not without rejecting special relativity) 
But so long as your materialism admits mass in general then 
photons have their place, as does anything which has either 
inertia or energy. 

I don't know what he does about abstract objects. 
It would definitely be tricky if you were not allowed at 
least to talk as if abstract entities existed, but you don't 
have to suppose that they are constituents of the contingent 

Roger Jones 
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