Ee —— 
Skc, 2] INCOME 103 
A good definition should always conform to two tests: 
it must be useful for scientific analysis; and it must 
harmonize with popular and instinctive usage. We shall 
see that the usual definitions of income fail in one or both 
of these requisites. Many fail to lend themselves to scien- 
tific analysis by committing the fallacy of double counting, 
others by confusing income and capital, while almost all fail 
to harmonize with popular usage by making out income 
larger or smaller than common sense would dictate. 
Like most familiar notions, the notion of income seems 
to the uninitiated clear enough without definition. But 
pitfalls which are unseen are for that very reason all the 
more dangerous. We shall point out a few of them by 
criticising, not the specific definitions of particular authors, 
but the general concepts of income which the reader is 
likely, more or less unconsciously, to have acquired. 
§ 2 
The concept of income which is the most common is 
that of ‘“money-income.” A business man’s ‘“money- 
income” means to him the money receipts from his busi- 
ness, less the money expenses of obtaining them. As 
applied to commercial affairs, this concept is nearly 
adequate, and in fact it coincides, as a special case, with the 
concept of income which we have adopted; for the 
services which a man’s business capital yields him usually 
consist exclusively of bringing him money, and the disserv- 
ices which it causes him, of taking money from him. Thus 
the net value of its services to him, or difference between 
the value of the services -and disservices, is simply the 
difference between the money brought in and the money 
taken away from him by his business. 
But while the concept of “money-income” is correct so 
far as it goes, it is far f om exhausting the complete in- 
come concept. As soon as we pass outside of commercial 
circles, we find cases in which money-receipts are evi-