The Two Types of Phenomenalism

Phenomenalism responds to scepticism about the physical world by making a logical link between our experience and the world of physical objects. There are two famous defences of Phenomenalism: Mill's 'metaphysical' account and Ayer's linguistic account.

MILL'S PHENOMENALISM

John Stuart Mill (An Examination of Sir William Hamilton's Philosophy, Ch. 11) begins by

saying we have only our experience to go on in establishing what there is. When we

interact with material objects, for example looking for something on a desk, we are

presented with a series of new sensations. Certain sensations which were possible come

about. I could move this piece of paper, and experience the colour of the surface beneath

it. There are all sorts of possible sensations that would occur under certain conditions.

We have come, from experience, to expect this sequence of sensation; we are certain it

will happen. And so we come to think of certain possibilities for sensation as being

permanently available, under certain conditions. Material objects are 'permanent

possibilities of sensation'.

We associate certain sensations, and the possibilities of other sensations, together, since

whenever I have one sensation, the conditions of having another associated with it are to

hand. These 'clusters' of possible sensations are what material objects are. A piece of

paper is the permanent possibility of certain sensations that we associate together. Only

some of the sensations in fact occur; but the material object is a collection of those that

do and those that could occur. We derive the complexity of ideas of space, distance,

perspective from the complex associations between sensations that we make

(automatically - none of this need be thought through!).

We then think of material objects as the cause of the sensations that do occur. This isn't

exactly wrong, though perhaps it is peculiar to think of a collection of possibilities

causing an actuality. Where we do go wrong, Mill thinks, is if we think this cause is

something that could exist quite independent on sensation. This is something we cannot

know, and could only lead to scepticism. Instead, there is no logical gap between

appearance and reality.

AYER'S LINGUISTIC PHENOMENALISM

A J Ayer takes a different tack (Language, Truth and Logic, Ch. 3). He defends

phenomenalism through his analysis of statements concerning material objects. He

claims that the function of philosophy is to give 'definitions in use', showing how the

sentences in which a symbol or type of symbol (such as 'table' or words for material

objects generally) occurs can be translated into equivalent sentences which don't contain

it or its synonyms. (He contrasts this with dictionary definitions, in which symbols are

defined in terms of synonyms.) Philosophical definitions, then, can deepen our

understanding of terms in a way dictionary definitions do not, i.e. they can still be

informative to someone who already knows what all the terms mean in the dictionary

sense.

It can happen that we discover the term is 'standing in for' something more complex.