What's the difference between pleonasm and tautology?

Pleonasm


Definition:

  • (n.) Redundancy of language in speaking or writing; the use of more words than are necessary to express the idea; as, I saw it with my own eyes.

Example Sentences:

  • (1) Therefore the term "psychogenic pain sensation" seems to be a pleonasm at first sight.
  • (2) A choice is necessary in all cases which takes into consideration the patient's interests and the cost of treatment and permits one to avoid pleonasms and illogical treatment.

Tautology


Definition:

  • (n.) A repetition of the same meaning in different words; needless repetition of an idea in different words or phrases; a representation of anything as the cause, condition, or consequence of itself, as in the following lines: --//The dawn is overcast, the morning lowers,/And heavily in clouds brings on the day. Addison.

Example Sentences:

  • (1) Two studies are reported in which subjects rated the acceptability of different tautological constructions either alone (Experiment 1) or with supporting contextual information (Experiment 2).
  • (2) Barton rubs Old Firm up the wrong way Joey Barton apologises ‘unreservedly’ after being sent home by Rangers Read more The phrase “Joey Barton Twitter storm” is pretty much a tautology, so it was no surprise that his decision to sign for Rangers in May had social media in a kerfuffle when his 2012 tweet – “I am a Celtic fan” – was dredged up so that it might be subject to calm and sober scrutiny from all concerned.
  • (3) These 5 were classified into 2 operations of varying the independent variable, 2 of holding the independent variable constant, and tautology.
  • (4) If Farage was tempted to reply that his opponent trades in a cut-price political rhetoric that reduces debate to a bewildering brew of slogans, tautologies and clap-lines, he chose instead to occupy the argumentative high ground – or as close as Ukippers get to it.
  • (5) What do tautological phrases such as Boys will be boys, A promise is a promise, or War is war mean and how are they understood?
  • (6) None of the other freedoms are as free as they were meant to be, so how about we make this freedom a bit less of a freedom to make it more in line with the other non-freedoms.” Caught up in the tautology of his argument, the prime minister went on to make ever wilder and contradictory claims.
  • (7) However, this tautologic upper limit does not uniquely define the critical duration.
  • (8) Duration judgments were explaned predominantly by succession, whereas succession judgments were explained tautologically or by mere "seeing."
  • (9) This is what passes for significant thought in the GOP: new scare facts colliding with new anecdotes of meetin’ folks, all to explain re-synonymized tautologies.
  • (10) Our results indicate that glucoreceptor cells in tissues perfused by carotid arteries may play a tautological role in the sympathetic response to hypoglycemia and imply that glucose-sensitive receptors must also be located elsewhere in the central nervous system or in the periphery.
  • (11) They are nothing more, Stewart now acknowledges, than tautologies.
  • (12) Confining the diagnosis of schizophrenia to the severe cases indicates a conservative, perhaps tautological, approach to this diagnosis.
  • (13) To avoid tautology, the nature of these was confirmed by immunostaining for epithelial membrane antigen (EMA) and factor VIII-related antigen (FVII RAg).
  • (14) The first is a tautology lacking explanatory power.
  • (15) The reasoning may be questioned because of faulty inferential leaps, undue reliance on the concept of 'maturity', the use of a tautology, ('The dependent person is...dependent'), internal contradictions, and a questionable analogy between children's and adults' behaviour.
  • (16) The basic tenet of twin biology, that most twin excess anomalies are due to MZs, is a myth self-perpetuated by a methodological tautology, and is false, at least for mortality.
  • (17) It is argued that since Heather & Robertson's 'new' approach incorporates a set of assumptions parallel to those of the disease concept it is equally tautological, and therefore does not represent the type of change in paradigm they propose.
  • (18) Historian and MP Tristram Hunt is indicted for "tautology and other errors".
  • (19) It is this devotion to the infinitely unknown that makes Hugo so meticulous in giving the reader Valjean's prison numbers; and why Valjean's name is almost a tautology.
  • (20) Forensic factors were found to be positively related to length of admission; and motivation for treatment--a problematic concept which has frequently been regarded as tautologous--is also discussed.