At first glance, there seems to be no difference between the words assume and presume. Their meanings are almost similar to one another. So, it should come as no surprise that these twins have the same root as well. Both the words have been derived from Latin sumere which means to take up or buy. The main difference here lies in the way they are ‘taken up’.
When ad- is added to the Latin root, the derivation is adsumere, now referred to as assume. To assume means to think of something as true but without proof or certain knowledge. Depending on the context, it can also mean to take responsibility, power or control. For example,’The rebels assumed control of the capitals.’ Its noun form, assumption, refers to the notion that is accepted as the truth without proof.
If you presume to love something, you must love the process of it much more than you love the finished product.
John Irving, American Novelist
Presume, on the other hand, is a better fit where a case is backed by probabilities as in ‘When the police returned empty handed, we presumed that the criminal had fled the building.’ Presume, however, can also carry the sense of ‘dare to’ or ‘go so far as’ (‘Don’t presume that you can handle the affairs of the company all alone’). Its noun form presumption is used in a similar sense and provides a basis for reasoning, for example, ‘My judgement is based on the presumption that humans act rationally and in their own interest’.
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The adjective form of presume, presumptuous carries a negative connotation and means undue confidence and rudeness. For example, ‘His claim that growth will touch 12% next quarter is presumptuous’ means that the claimant is overconfident to the point of arrogance.
Time for a bonus! When prefixed with con- we get the word consumere which is the ancestor of the modern word consume meaning to eat, drink or ingest. Apart from these, it can also be used figuratively. For instance, if a process requires a lot of energy, we can say that it consumes a lot of energy. Also, if someone is consumed by jealousy, instead of conveying that they are being eaten by the feeling, it means that they are feeling overwhelmed by it.
I presume that the following table will prove helpful when you deal with the exercises ahead.
Table Summary:
| Prefix | Word | Suffix | Meaning |
| Consume | eat, drink or ingest; to completely fill someone’s mind. | ||
| Assume | Suppose something to be the case without proof | ||
| Assume | -tion | A notion that has been taken as the truth without proof | |
| Presume | suppose that something is the case on the basis of probability | ||
| Presume | -tion | an idea that is taken to be true on the basis of probability | |
| Presume | -tuous | Being overconfident or impudent |
