Knowledge and modality

Kripke claims that there are necessary a posteriori truths and contingent a priori truths. These claims challenge the traditional Kantian view that

1. (K)
   All knowledge of necessary truths is a priori and all a priori knowledge is of necessary truths.
    

Kripke’s claims continue to be resisted, which indicates that the Kantian view remains attractive. My goal is to identify the most plausible principles linking the epistemic and the modal. My strategy for identifying the principles is to investigate two related questions. Are there compelling general supporting arguments for (K)? Are there decisive counterexamples to (K)? My investigation uncovers two intuitively plausible principles that are not open to decisive counterexamples but which enjoy no compelling independent support.

     

Truthmakers and modality

This paper attempts to locate, within an actualist ontology, truthmakers for modal truths: truths of the form <Possibly, p> or <Necessarily, p>. In Sect. 1 I motivate the demand for substantial truthmakers for modal truths. In Sect. 2 I criticise Armstrong’s account of truthmakers for modal truths. In Sect. 3 I examine essentialism and defend an account of what makes essentialist attributions true, but I argue that this does not solve the problem of modal truth in general. In Sect. 4 I discuss, and dismiss, a theistic account of the source of modal truth proposed by Alexander Pruss. In Sect. 5 I offer a means of (dis)solving the problem.     

Variations in characteristic perceptual asymmetry: modality specific and modality general components.

The current study investigates sources of between-subjects variation in asymmetry scores on visual half-field and dichotic listening tasks. For each of these presentation modalities, subjects were given multiple laterality tasks. Results indicate that about 50% of the between-subjects variations in asymmetry scores in each modality is attributable to individual differences in perceptual asymmetries that are not stimulus-specific, referred to as "characteristic perceptual asymmetries" in this paper. In addition, the question of whether individual differences in characteristic perceptual asymmetries are modality specific, modality general, or both was investigated by entering subjects' asymmetry scores from visual half-field and dichotic listening tasks into a principal component analysis. The results of this analysis indicate that there are both modality specific and modality general influences on subjects' characteristic perceptual asymmetries.     

Dutch modality exclusivity norms: Simulating perceptual modality in space

Perceptual information is important for the meaning of nouns. We present modality exclusivity norms for 485 Dutch nouns rated on visual, auditory, haptic, gustatory, and olfactory associations. We found these nouns are highly multimodal. They were rated most dominant in vision, and least in olfaction. A factor analysis identified two main dimensions: one loaded strongly on olfaction and gustation (reflecting joint involvement in flavor), and a second loaded strongly on vision and touch (reflecting joint involvement in manipulable objects). In a second study, we validated the ratings with similarity judgments. As expected, words from the same dominant modality were rated more similar than words from different dominant modalities; but – more importantly – this effect was enhanced when word pairs had high modality strength ratings. We further demonstrated the utility of our ratings by investigating whether perceptual modalities are differentially experienced in space, in a third study. Nouns were categorized into their dominant modality and used in a lexical decision experiment where the spatial position of words was either in proximal or distal space. We found words dominant in olfaction were processed faster in proximal than distal space compared to the other modalities, suggesting olfactory information is mentally simulated as “close” to the body. Finally, we collected ratings of emotion (valence, dominance, and arousal) to assess its role in perceptual space simulation, but the valence did not explain the data. So, words are processed differently depending on their perceptual associations, and strength of association is captured by modality exclusivity ratings.     

The modality effect and articulation

The two experiments reported in this paper investigate the influences of irrelevant articulation on the modality effect in serial recall. Subjects performed a post-list distractor task, which involved generating a well-learned alphabetic sequence for five seconds. The modality effect was impaired when subjects vocalized the letters aloud, but was unaffected by whether the sequence was silently mouthed or silently written. These results show that the modality effect does not arise from the contribution of an articulatory code to recall of the most recent auditory items. They also question the functional equivalence of recency effects for auditory, mouthed and lipread stimuli. On the basis of these and other findings, a multi-component approach to recency effects is proposed.     

Effects of standard modality, comparison modality and retention interval on matching of form

Garvill, J. & Molander, B. Effects of standard modality, comparison modality and retention interval on matching of form. Scand. J. Psychol., 1973, 14, 203–206.MdashIntra-modal and cross-modal matching of nonsense forms was studied in a 2 (standard modalities: visual vs. tactual) by 2 (comparison modalities: visual vs. tactual) by 3 (intervals between standard and comparison: 1, 10 and 30 sec) factorial experiment. The errors were divided into false negatives and false positives. Significant effects of standard modality and of comparison modality were found for false negatives. For false positives the most prominent effect was an interaction between the standard modality and the comparison modality. Retention interval had no effect in any of the modality conditions. The effects are discussed in terms of differential information processing capacity for the visual and the tactual modalities.     

Verbs,time, and modality

In the first part of this paper it is argued that Vendler's classification of verbs into aspectual categories, called activities, accomplishments, achievements, and states, is better seen as classifying the meanings of sentences, and a recursive scheme for describing the aspectual character of sentences is presented. In the second part, this scheme is applied to the discussion of the epistemic and deontic meanings of the modal verbs must, will, and may. In particular, the relation between the “future” and “nonfuture” senses of epistemic will is examined.     

Powers, causation, and modality

A complex theory concerning powers, natures, and causal necessity has emerged from the writings of P. H. Hare, E. H. Madden, and R. Harré. In the course of rebutting objections that other critics have raised to the power account of causation, I correct three of its genuine difficulties: its attempt to analyze power attributions in terms of conditional statements; its characterization of the relation between something's powers and its nature; and its doctrines concerning conceptual necessity. The resulting interpretation of causal modalities is then subsumed under a more general power account of modality, related at a number of points to considerations concerning powers, and further illustrating their philosophical importance.     

Sense modality switching and serial leaming

This investigation examined the effect of sense modality switching ofinformation at various positions of a serial learning task. Different numbers of flashes of light and different numbers of “blips” ofa pure tone were used as signalsin a four-position serial learning task. The design of the study involved a switch in sense modality at each one of the four possible positions in the series. Thus, it was possible to determine if the transmission of information through one sense modality makes it progressively more difficult or more time consuming to switch to another source of information transmitted through another modality. The results generally supported the contention that, as information is received through a particular modality, there is a build-up of the disruption involved in switching sense modality.